functions of a literature review

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What is the Purpose of a Literature Review?

4-minute read

• 23rd October 2023

If you’re writing a research paper or dissertation , then you’ll most likely need to include a comprehensive literature review . In this post, we’ll review the purpose of literature reviews, why they are so significant, and the specific elements to include in one. Literature reviews can:

1. Provide a foundation for current research.

2. Define key concepts and theories.

3. Demonstrate critical evaluation.

4. Show how research and methodologies have evolved.

5. Identify gaps in existing research.

6. Support your argument.

Keep reading to enter the exciting world of literature reviews!

What is a Literature Review?

A literature review is a critical summary and evaluation of the existing research (e.g., academic journal articles and books) on a specific topic. It is typically included as a separate section or chapter of a research paper or dissertation, serving as a contextual framework for a study. Literature reviews can vary in length depending on the subject and nature of the study, with most being about equal length to other sections or chapters included in the paper. Essentially, the literature review highlights previous studies in the context of your research and summarizes your insights in a structured, organized format. Next, let’s look at the overall purpose of a literature review.

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Literature reviews are considered an integral part of research across most academic subjects and fields. The primary purpose of a literature review in your study is to:

Provide a Foundation for Current Research

Since the literature review provides a comprehensive evaluation of the existing research, it serves as a solid foundation for your current study. It’s a way to contextualize your work and show how your research fits into the broader landscape of your specific area of study.  

Define Key Concepts and Theories

The literature review highlights the central theories and concepts that have arisen from previous research on your chosen topic. It gives your readers a more thorough understanding of the background of your study and why your research is particularly significant .

Demonstrate Critical Evaluation 

A comprehensive literature review shows your ability to critically analyze and evaluate a broad range of source material. And since you’re considering and acknowledging the contribution of key scholars alongside your own, it establishes your own credibility and knowledge.

Show How Research and Methodologies Have Evolved

Another purpose of literature reviews is to provide a historical perspective and demonstrate how research and methodologies have changed over time, especially as data collection methods and technology have advanced. And studying past methodologies allows you, as the researcher, to understand what did and did not work and apply that knowledge to your own research.  

Identify Gaps in Existing Research

Besides discussing current research and methodologies, the literature review should also address areas that are lacking in the existing literature. This helps further demonstrate the relevance of your own research by explaining why your study is necessary to fill the gaps.

Support Your Argument

A good literature review should provide evidence that supports your research questions and hypothesis. For example, your study may show that your research supports existing theories or builds on them in some way. Referencing previous related studies shows your work is grounded in established research and will ultimately be a contribution to the field.  

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• UConn Library
• Literature Review: The What, Why and How-to Guide
• Introduction

Literature Review: The What, Why and How-to Guide — Introduction

• Getting Started
• How to Pick a Topic
• Strategies to Find Sources
• Evaluating Sources & Lit. Reviews
• Tips for Writing Literature Reviews
• Writing Literature Review: Useful Sites
• Citation Resources
• Other Academic Writings

What are Literature Reviews?

So, what is a literature review? "A literature review is an account of what has been published on a topic by accredited scholars and researchers. In writing the literature review, your purpose is to convey to your reader what knowledge and ideas have been established on a topic, and what their strengths and weaknesses are. As a piece of writing, the literature review must be defined by a guiding concept (e.g., your research objective, the problem or issue you are discussing, or your argumentative thesis). It is not just a descriptive list of the material available, or a set of summaries." Taylor, D.  The literature review: A few tips on conducting it . University of Toronto Health Sciences Writing Centre.

Goals of Literature Reviews

What are the goals of creating a Literature Review?  A literature could be written to accomplish different aims:

• To develop a theory or evaluate an existing theory
• To summarize the historical or existing state of a research topic
• Identify a problem in a field of research 

Baumeister, R. F., & Leary, M. R. (1997). Writing narrative literature reviews .  Review of General Psychology , 1 (3), 311-320.

What kinds of sources require a Literature Review?

• A research paper assigned in a course
• A thesis or dissertation
• A grant proposal
• An article intended for publication in a journal

All these instances require you to collect what has been written about your research topic so that you can demonstrate how your own research sheds new light on the topic.

Types of Literature Reviews

What kinds of literature reviews are written?

Narrative review: The purpose of this type of review is to describe the current state of the research on a specific topic/research and to offer a critical analysis of the literature reviewed. Studies are grouped by research/theoretical categories, and themes and trends, strengths and weakness, and gaps are identified. The review ends with a conclusion section which summarizes the findings regarding the state of the research of the specific study, the gaps identify and if applicable, explains how the author's research will address gaps identify in the review and expand the knowledge on the topic reviewed.

• Example : Predictors and Outcomes of U.S. Quality Maternity Leave: A Review and Conceptual Framework:  10.1177/08948453211037398  

Systematic review : "The authors of a systematic review use a specific procedure to search the research literature, select the studies to include in their review, and critically evaluate the studies they find." (p. 139). Nelson, L. K. (2013). Research in Communication Sciences and Disorders . Plural Publishing.

• Example : The effect of leave policies on increasing fertility: a systematic review:  10.1057/s41599-022-01270-w

Meta-analysis : "Meta-analysis is a method of reviewing research findings in a quantitative fashion by transforming the data from individual studies into what is called an effect size and then pooling and analyzing this information. The basic goal in meta-analysis is to explain why different outcomes have occurred in different studies." (p. 197). Roberts, M. C., & Ilardi, S. S. (2003). Handbook of Research Methods in Clinical Psychology . Blackwell Publishing.

• Example : Employment Instability and Fertility in Europe: A Meta-Analysis:  10.1215/00703370-9164737

Meta-synthesis : "Qualitative meta-synthesis is a type of qualitative study that uses as data the findings from other qualitative studies linked by the same or related topic." (p.312). Zimmer, L. (2006). Qualitative meta-synthesis: A question of dialoguing with texts .  Journal of Advanced Nursing , 53 (3), 311-318.

• Example : Women’s perspectives on career successes and barriers: A qualitative meta-synthesis:  10.1177/05390184221113735

Literature Reviews in the Health Sciences

• UConn Health subject guide on systematic reviews Explanation of the different review types used in health sciences literature as well as tools to help you find the right review type
• << Previous: Getting Started
• Next: How to Pick a Topic >>
• Last Updated: Sep 21, 2022 2:16 PM
• URL: https://guides.lib.uconn.edu/literaturereview

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Methodology

• How to Write a Literature Review | Guide, Examples, & Templates

How to Write a Literature Review | Guide, Examples, & Templates

Published on January 2, 2023 by Shona McCombes . Revised on September 11, 2023.

What is a literature review? A literature review is a survey of scholarly sources on a specific topic. It provides an overview of current knowledge, allowing you to identify relevant theories, methods, and gaps in the existing research that you can later apply to your paper, thesis, or dissertation topic .

There are five key steps to writing a literature review:

• Search for relevant literature
• Evaluate sources
• Identify themes, debates, and gaps
• Outline the structure
• Write your literature review

A good literature review doesn’t just summarize sources—it analyzes, synthesizes , and critically evaluates to give a clear picture of the state of knowledge on the subject.

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Table of contents

What is the purpose of a literature review, examples of literature reviews, step 1 – search for relevant literature, step 2 – evaluate and select sources, step 3 – identify themes, debates, and gaps, step 4 – outline your literature review’s structure, step 5 – write your literature review, free lecture slides, other interesting articles, frequently asked questions, introduction.

• Quick Run-through
• Step 1 & 2

When you write a thesis , dissertation , or research paper , you will likely have to conduct a literature review to situate your research within existing knowledge. The literature review gives you a chance to:

• Demonstrate your familiarity with the topic and its scholarly context
• Develop a theoretical framework and methodology for your research
• Position your work in relation to other researchers and theorists
• Show how your research addresses a gap or contributes to a debate
• Evaluate the current state of research and demonstrate your knowledge of the scholarly debates around your topic.

Writing literature reviews is a particularly important skill if you want to apply for graduate school or pursue a career in research. We’ve written a step-by-step guide that you can follow below.

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See an example

Writing literature reviews can be quite challenging! A good starting point could be to look at some examples, depending on what kind of literature review you’d like to write.

• Example literature review #1: “Why Do People Migrate? A Review of the Theoretical Literature” ( Theoretical literature review about the development of economic migration theory from the 1950s to today.)
• Example literature review #2: “Literature review as a research methodology: An overview and guidelines” ( Methodological literature review about interdisciplinary knowledge acquisition and production.)
• Example literature review #3: “The Use of Technology in English Language Learning: A Literature Review” ( Thematic literature review about the effects of technology on language acquisition.)
• Example literature review #4: “Learners’ Listening Comprehension Difficulties in English Language Learning: A Literature Review” ( Chronological literature review about how the concept of listening skills has changed over time.)

You can also check out our templates with literature review examples and sample outlines at the links below.

Download Word doc Download Google doc

Before you begin searching for literature, you need a clearly defined topic .

If you are writing the literature review section of a dissertation or research paper, you will search for literature related to your research problem and questions .

Make a list of keywords

Start by creating a list of keywords related to your research question. Include each of the key concepts or variables you’re interested in, and list any synonyms and related terms. You can add to this list as you discover new keywords in the process of your literature search.

• Social media, Facebook, Instagram, Twitter, Snapchat, TikTok
• Body image, self-perception, self-esteem, mental health
• Generation Z, teenagers, adolescents, youth

Search for relevant sources

Use your keywords to begin searching for sources. Some useful databases to search for journals and articles include:

• Your university’s library catalogue
• Google Scholar
• Project Muse (humanities and social sciences)
• Medline (life sciences and biomedicine)
• EconLit (economics)
• Inspec (physics, engineering and computer science)

You can also use boolean operators to help narrow down your search.

Make sure to read the abstract to find out whether an article is relevant to your question. When you find a useful book or article, you can check the bibliography to find other relevant sources.

You likely won’t be able to read absolutely everything that has been written on your topic, so it will be necessary to evaluate which sources are most relevant to your research question.

For each publication, ask yourself:

• What question or problem is the author addressing?
• What are the key concepts and how are they defined?
• What are the key theories, models, and methods?
• Does the research use established frameworks or take an innovative approach?
• What are the results and conclusions of the study?
• How does the publication relate to other literature in the field? Does it confirm, add to, or challenge established knowledge?
• What are the strengths and weaknesses of the research?

Make sure the sources you use are credible , and make sure you read any landmark studies and major theories in your field of research.

You can use our template to summarize and evaluate sources you’re thinking about using. Click on either button below to download.

Take notes and cite your sources

As you read, you should also begin the writing process. Take notes that you can later incorporate into the text of your literature review.

It is important to keep track of your sources with citations to avoid plagiarism . It can be helpful to make an annotated bibliography , where you compile full citation information and write a paragraph of summary and analysis for each source. This helps you remember what you read and saves time later in the process.

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To begin organizing your literature review’s argument and structure, be sure you understand the connections and relationships between the sources you’ve read. Based on your reading and notes, you can look for:

• Trends and patterns (in theory, method or results): do certain approaches become more or less popular over time?
• Themes: what questions or concepts recur across the literature?
• Debates, conflicts and contradictions: where do sources disagree?
• Pivotal publications: are there any influential theories or studies that changed the direction of the field?
• Gaps: what is missing from the literature? Are there weaknesses that need to be addressed?

This step will help you work out the structure of your literature review and (if applicable) show how your own research will contribute to existing knowledge.

• Most research has focused on young women.
• There is an increasing interest in the visual aspects of social media.
• But there is still a lack of robust research on highly visual platforms like Instagram and Snapchat—this is a gap that you could address in your own research.

There are various approaches to organizing the body of a literature review. Depending on the length of your literature review, you can combine several of these strategies (for example, your overall structure might be thematic, but each theme is discussed chronologically).

Chronological

The simplest approach is to trace the development of the topic over time. However, if you choose this strategy, be careful to avoid simply listing and summarizing sources in order.

Try to analyze patterns, turning points and key debates that have shaped the direction of the field. Give your interpretation of how and why certain developments occurred.

If you have found some recurring central themes, you can organize your literature review into subsections that address different aspects of the topic.

For example, if you are reviewing literature about inequalities in migrant health outcomes, key themes might include healthcare policy, language barriers, cultural attitudes, legal status, and economic access.

Methodological

If you draw your sources from different disciplines or fields that use a variety of research methods , you might want to compare the results and conclusions that emerge from different approaches. For example:

• Look at what results have emerged in qualitative versus quantitative research
• Discuss how the topic has been approached by empirical versus theoretical scholarship
• Divide the literature into sociological, historical, and cultural sources

Theoretical

A literature review is often the foundation for a theoretical framework . You can use it to discuss various theories, models, and definitions of key concepts.

You might argue for the relevance of a specific theoretical approach, or combine various theoretical concepts to create a framework for your research.

Like any other academic text , your literature review should have an introduction , a main body, and a conclusion . What you include in each depends on the objective of your literature review.

The introduction should clearly establish the focus and purpose of the literature review.

Depending on the length of your literature review, you might want to divide the body into subsections. You can use a subheading for each theme, time period, or methodological approach.

As you write, you can follow these tips:

• Summarize and synthesize: give an overview of the main points of each source and combine them into a coherent whole
• Analyze and interpret: don’t just paraphrase other researchers — add your own interpretations where possible, discussing the significance of findings in relation to the literature as a whole
• Critically evaluate: mention the strengths and weaknesses of your sources
• Write in well-structured paragraphs: use transition words and topic sentences to draw connections, comparisons and contrasts

In the conclusion, you should summarize the key findings you have taken from the literature and emphasize their significance.

When you’ve finished writing and revising your literature review, don’t forget to proofread thoroughly before submitting. Not a language expert? Check out Scribbr’s professional proofreading services !

This article has been adapted into lecture slides that you can use to teach your students about writing a literature review.

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If you want to know more about the research process , methodology , research bias , or statistics , make sure to check out some of our other articles with explanations and examples.

• Sampling methods
• Simple random sampling
• Stratified sampling
• Cluster sampling
• Likert scales
• Reproducibility

 Statistics

• Null hypothesis
• Statistical power
• Probability distribution
• Effect size
• Poisson distribution

Research bias

• Optimism bias
• Cognitive bias
• Implicit bias
• Hawthorne effect
• Anchoring bias
• Explicit bias

A literature review is a survey of scholarly sources (such as books, journal articles, and theses) related to a specific topic or research question .

It is often written as part of a thesis, dissertation , or research paper , in order to situate your work in relation to existing knowledge.

There are several reasons to conduct a literature review at the beginning of a research project:

• To familiarize yourself with the current state of knowledge on your topic
• To ensure that you’re not just repeating what others have already done
• To identify gaps in knowledge and unresolved problems that your research can address
• To develop your theoretical framework and methodology
• To provide an overview of the key findings and debates on the topic

Writing the literature review shows your reader how your work relates to existing research and what new insights it will contribute.

The literature review usually comes near the beginning of your thesis or dissertation . After the introduction , it grounds your research in a scholarly field and leads directly to your theoretical framework or methodology .

A literature review is a survey of credible sources on a topic, often used in dissertations , theses, and research papers . Literature reviews give an overview of knowledge on a subject, helping you identify relevant theories and methods, as well as gaps in existing research. Literature reviews are set up similarly to other  academic texts , with an introduction , a main body, and a conclusion .

An  annotated bibliography is a list of  source references that has a short description (called an annotation ) for each of the sources. It is often assigned as part of the research process for a  paper .  

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• University of Texas Libraries

Literature Reviews

• What is a literature review?
• Steps in the Literature Review Process
• Define your research question
• Determine inclusion and exclusion criteria
• Choose databases and search
• Review Results
• Synthesize Results
• Analyze Results
• Librarian Support
• Artificial Intelligence (AI) Tools

What is a Literature Review?

A literature or narrative review is a comprehensive review and analysis of the published literature on a specific topic or research question. The literature that is reviewed contains: books, articles, academic articles, conference proceedings, association papers, and dissertations. It contains the most pertinent studies and points to important past and current research and practices. It provides background and context, and shows how your research will contribute to the field. 

A literature review should: 

• Provide a comprehensive and updated review of the literature;
• Explain why this review has taken place;
• Articulate a position or hypothesis;
• Acknowledge and account for conflicting and corroborating points of view

From  S age Research Methods

Purpose of a Literature Review

A literature review can be written as an introduction to a study to:

• Demonstrate how a study fills a gap in research
• Compare a study with other research that's been done

Or it can be a separate work (a research article on its own) which:

• Organizes or describes a topic
• Describes variables within a particular issue/problem

Limitations of a Literature Review

Some of the limitations of a literature review are:

• It's a snapshot in time. Unlike other reviews, this one has beginning, a middle and an end. There may be future developments that could make your work less relevant.
• It may be too focused. Some niche studies may miss the bigger picture.
• It can be difficult to be comprehensive. There is no way to make sure all the literature on a topic was considered.
• It is easy to be biased if you stick to top tier journals. There may be other places where people are publishing exemplary research. Look to open access publications and conferences to reflect a more inclusive collection. Also, make sure to include opposing views (and not just supporting evidence).

Source: Grant, Maria J., and Andrew Booth. “A Typology of Reviews: An Analysis of 14 Review Types and Associated Methodologies.” Health Information & Libraries Journal, vol. 26, no. 2, June 2009, pp. 91–108. Wiley Online Library, doi:10.1111/j.1471-1842.2009.00848.x.

Librarian Assistance

For help, please contact the librarian for your subject area.  We have a guide to library specialists by subject .

• Last Updated: Aug 26, 2024 5:59 AM
• URL: https://guides.lib.utexas.edu/literaturereviews

Libraries | Research Guides

Literature reviews, what is a literature review, learning more about how to do a literature review.

• Planning the Review
• The Research Question
• Choosing Where to Search
• Organizing the Review
• Writing the Review

A literature review is a review and synthesis of existing research on a topic or research question. A literature review is meant to analyze the scholarly literature, make connections across writings and identify strengths, weaknesses, trends, and missing conversations. A literature review should address different aspects of a topic as it relates to your research question. A literature review goes beyond a description or summary of the literature you have read. 

• Sage Research Methods Core This link opens in a new window SAGE Research Methods supports research at all levels by providing material to guide users through every step of the research process. SAGE Research Methods is the ultimate methods library with more than 1000 books, reference works, journal articles, and instructional videos by world-leading academics from across the social sciences, including the largest collection of qualitative methods books available online from any scholarly publisher. – Publisher

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• Last Updated: Jul 8, 2024 11:22 AM
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Literature Reviews

• First Online: 07 June 2024

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• George P. Moschis 2  

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A literature review is a critical component of a scientific study and holds significant importance, as literature reviews serve several important functions within the research process:

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Anthony, D. R., Gucciardi, D. F., & Gordon, S. (2016). A meta-study of qualitative research on mental toughness development. International Review of Sport and Exercise Psychology, 9 (1), 160–190.

Article   Google Scholar  

Arksey, H., & O’Malley, L. (2005). Scoping studies: Towards a methodological framework. International Journal of Social Research Methodology, 8 (1), 19–32.

Arnold, R., & Fletcher, D. (2012). A research synthesis and taxonomic classification of the organizational stressors encountered by sport performers. Journal of Sport and Exercise Psychology, 34 (3), 397–429.

Banning, J. H. (2005). Ecological triangulation: An approach for qualitative meta-synthesis. What works for youth with disabilities project . US Department of Education, School of Education, Colorado: Colorado State University.

Google Scholar  

Barnett-Page, E., & Thomas, J. (2009). Methods for the synthesis of qualitative research: A critical review. BMC Medical Research Methodology, 9 , 59. https://doi.org/10.1186/1471-2288-9-59

Breretona, P., Kitchenhama, B. A., Budgenb, D., Turnera, M., & Khalilc, M. (2007). Lessons from applying the systematic literature review process within the software engineering domain. Journal of Systems and Software, 80 (4), 571–583.

Britten, N., Campbell, R., Pope, C., Donovan, J., Morgan, M., & Pill, R. (2002). Using meta ethnography to synthesise qualitative research: A worked example. Journal of Health Services Research & Policy, 7 (4), 209–215.

Brunton, G., Oliver, S., Oliver, K., & Lorenc, T. (2006). A synthesis of research addressing children’s, young people’s and parents’ views of walking and cycling for transport . EPPI-Centre, Social Science. Research Unit, Institute of Education, University of London.

Cheung, M. W. L., & Vijayakumar, R. (2016). A guide to conducting a meta-analysis. Neuropsychology Review, 26 , 121–128. https://doi.org/10.1007/s11065-016-9319-z

Dhollande, S., Taylor, A., Meyer, S., & Scott, M. (2021). Conducting integrative reviews: A guide for novice nursing researchers. Journal of Research in Nursing, 26 (5), 427–438. https://doi.org/10.1177/1744987121997907

Dieckmann, N. F., Malle, B. F., & Bodner, T. E. (2009). An Empirical Assessment of Meta-Analytic Practice. Review of General Psychology 13 (2), 101–15.

Dixon-Woods, M., Cavers, D., Agarwal, S., Annandale, E., Arthur, A., Harvey, J., Hsu, R., Katbamna, S., Olsen, R., & Smith, L. (2006). Conducting a critical interpretive synthesis of the literature on access to healthcare by vulnerable groups. BMC Medical Research Methodology, 6 (1), 1.

Donthu, N., Kumar, S., Mukherjee, D., Pandey, N., & Lim, W. M. (2001). How to conduct a bibliometric analysis: An overview and guidelines. Journal of Business Research, 133 , 285–296.

Drew, K., Morris, R., Tod, D., & Eubank, M. (2019). A meta-study of qualitative research on the junior-to-senior transition in sport. Psychology of Sport and Exercise, 45 , 101556.

Evans, D., & Fitzgerald, M. (2002). Reasons for physically restraining patients and residents: A systematic review and content analysis. International Journal of Nursing Studies, 39 , 739–743. https://doi.org/10.1016/S0020-7489(02)00015-9

Ewing, R., & Cervero, R. (2010). Travel and the built environment: A meta-analysis. Journal of the American Planning Association, 76 (3), 265–294.

Fisher, C. L., Maloney, E., Glogowski, E., Hurley, K., Edgerson, S., Lichtenthal, W. G., Kissane, D., & Bylund, C. (2014). Talking about familial breast cancer risk topics and strategies to enhance mother–daughter interactions. Qualitative Health Research, 24 (4), 517–535.

Flemming, K. (2010). Synthesis of quantitative and qualitative research: An example using critical interpretive synthesis. Journal of Advanced Nursing, 66 (1), 201–217.

Glaser, B., & Strauss, A. (1967). The discovery of grounded theory . Aldine.

Glass, G. V. (1976). Primary, secondary, and meta-analysis of research. Educational Researcher, 5 (10), 3–8.

Grant, M. J., & Booth, A. (2009). A typology of reviews: An analysis of 14 review types and associated methodologies. Health Information and Libraries Journal, 26 (2), 91–108.

Green, B. N., Johnson, C. D., & Adams, A. (2001). Writing narrative literature reviews for peer-reviewed journals: Secrets of the trade. Journal of Sports Chiropractic & Rehabilitation, 15 (1), 5–19.

Greenhalgh, T., Robert, G., Macfarlane, F., Bate, P., & Kyriakidou, O. (2004). Diffusion of innovations in service organizations: Systematic review and recommendations. The Milbank Quarterly, 82 (4), 581–629.

Hackenberger, B. K. (2020). Bayesian meta-analysis now—Let’s do it. Croatian Medical Journal, 61 (6), 564–568. https://doi.org/10.3325/cmj.2020.61.564

Hansen, C., Steinmetz, H., & Block, J. (2022). How to conduct a meta-analysis in eight steps: A practical guide. Management Review Quarterly, 72 , 1–19. https://doi.org/10.1007/s11301-021-00247-4

Harden, A., Garcia, J., Oliver, S., Rees, R., Shepherd, J., Brunton, G., & Oakley, A. (2004). Applying systematic review methods to studies of people’s views: An example from public health research. Journal of Epidemiology and Community Health, 58 , 794–800. https://doi.org/10.1136/jech.2003.014829

Harden, S. M., McEwan, D., Sylvester, B. D., Kaulius, M., Ruissen, G., Burke, S. M., Estabrooks, P. A., & Beauchamp, M. R. (2015). Understanding for whom, under what conditions, and how group-based physical activity interventions are successful: A realist review. BMC Public Health, 15 (1), 1.

Herber, O. R., Bücker, B., Metzendorf, M.-I., & Barroso, J. (2017). A qualitative meta-summary using Sandelowski and Barroso’s method for synthesizing qualitative research to explore barriers and facilitators to self-care in heart failure patients. European Journal of Cardiovascular Nursing, 16 , 662–677. https://doi.org/10.1177/1474515117711007

Herber, O. R., Kastaun, S., Wilm, S., & Barroso, J. (2019). From qualitative meta-summary to qualitative meta-synthesis: Introducing a new situation-specific theory of barriers and facilitators for self-Care in Patients with Heart Failure. Qualitative Health Research, 29 (1), 96–106.

Hoffman, D. L., & Holbrook, M. B. (1993). The intellectual structure of consumer research. Journal of Consumer Research, 19 (4), 505–517.

Kitchenham, B., & Charters, S. (2007). Guidelines for performing systematic literature reviews in software engineering . In EBSE technical report. Software Engineering Group, School of Computer Science and Mathematics, Keele University, Department of Computer Science, University of Durham.

Kuhn, T. S. (1970). The structure of scientific revolutions (International encyclopedia of unified science) (Vol. 2(2)). University of Chicago Press.

Levac, D., Colquhoun, H., & O’Brien, K. K. (2010). Scoping studies: Advancing the methodology. Implementation Science, 5 (1), 69. https://doi.org/10.1186/1748-5908-5-69

Lim, W. M., & Kumar, S. (2024). Guidelines for interpreting the results of bibliometric analysis: A sensemaking approach. Global Business and Organizational Excellence, 43 (2), 17–26. https://doi.org/10.1002/joe.22229

Limkakeng, A. T., Jr., Herling de Oliveira, L. L., Moreira, T., Phadtare, A., Garcia Rodrigues, C., Hocker, M. B., McKinney, R., Voils, C. I., & Pietrobon, R. (2014). Systematic review and metasummary of attitudes toward research in emergency medical conditions. Journal of Medical Ethics, 40 (6), 401–408.

Lindell, M. K., & Perry, R. W. (2000). Household adjustment to earthquake hazard: A review of research. Environment and Behavior, 32 (4), 461–501.

Lucas, P. J., Baird, J., Arai, L., Law, C., & Roberts, H. M. (2007). Worked examples of alternative methods for the synthesis of qualitative and quantitative research in systematic reviews. BMC Medical Research Methodology, 7 (1), 4.

Mak, S., & Thomas, A. (2022). Steps for conducting a scoping review. Journal of Graduate Medical Education, 14 (5), 565–567.

Malekpour, S., Brown, R. R., & de Haan, F. J. (2015). Strategic planning of urban infrastructure for environmental sustainability: Understanding the past to intervene for the future. Cities, 46 , 67–75.

Mikkonen, K., & Kääriäinen, M. (2020). Content analysis in systematic reviews. In H. Kyngäs, K. Mikkonen, & M. Kääriäinen (Eds.), The application of content analysis in nursing science research . Springer. https://doi.org/10.1007/978-3-030-30199-6_10

Chapter   Google Scholar  

Moschis, G. P. (1990). Approaches to the study of consumer behavior in late life. Advances in Consumer Research, XVIII , 517–520.

Moschis, G. P. (1994). Consumer behavior in later life: Multidisciplinary contributions and implication for research. Journal of the Academy of Marketing Science, 22 (3), 195–204.

Neely, E., Walton, M., & Stephens, C. (2014). Young people’s food practices and social relationships. A thematic synthesis. Appetite, 82 , 50–60.

Noblit, G. W., & Hare, R. D. (1988). Meta-ethnography: Synthesizing qualitative studies . Sage.

Book   Google Scholar  

Paré, G., Trudel, M.-C., Jaana, M., & Kitsiou, S. (2015). Synthesizing information systems knowledge: A typology of literature reviews. Information & Management, 52 , 183–199.

Paterson, B. L., Thorne, S. E., Canam, C., & Jillings, C. (2001). Meta-study of qualitative health research. A practical guide to meta-analysis and meta-synthesis . Sage Publications.

Paul, J., Khatri, P., & Duggal, H. K. (2023). Frameworks for developing impactful systematic literature reviews and theory building: What, why and how? Journal of Decision Systems . https://doi.org/10.1080/12460125.2023.2197700

Paul, J., Martinez, L. F., Singh, R. K., & Koklic, M. K. (2024). Systematic literature reviews in consumer studies. International Journal of Consumer Studies , Call for Papers—Annual Special Issue: Submission period: February 15–May 31, 2024 https://onlinelibrary.wiley.com/page/journal/14706431/homepage/callforpapers . Downloaded on January 5, 2024.

Pawson, R., Greenhalgh, T., Harvey, G., & Walshe, K. (2005). Realist review: A new method of systematic review designed for complex policy interventions. Journal of Health Services Research and Policy, 70 (1), 21–34.

Pollock, D., Davies, E. L., Peters, M. D., et al. (2021). Undertaking a scoping review: A practical guide for nursing and midwifery students, clinicians, researchers, and academics. Journal of Advanced Nursing, 77 , 2102–2113.

Popay, J., Roberts, H., Sowden, A., Petticrew, M., Arai, L., Rodgers, M., Britten, N., Roen, K., & Duffy, S. (2006). Guidance on the conduct of narrative synthesis in systematic reviews . A product from the ESRC methods programme Version 1:b92.

Reis, D. J., Kaizer, A. M., Kinney, A. R., Bahraini, N. H., Holliday, R., Forster, J. E., & Brenner, L. A. (2023). A practical guide to random-effects Bayesian meta-analyses with application to the psychological trauma and suicide literature. Psychological Trauma: Theory, Research, Practice, and Policy, 15 (1), 121–130. https://doi.org/10.1037/tra0001316

Ridgway, N. M., Kukar-Kinney, M., & Monroe, K. B. (2008). An expanded conceptualization and a new measure of compulsive buying. Journal of Consumer Research, 35 (4), 622–639.

Rigolon, A. (2016). A complex landscape of inequity in access to urban parks: A literature review. Landscape and Urban Planning, 153 , 160–169.

Ritzer, G. (1991). Metatheorizing in Sociology . Lexington Books.

Roberts, K. A., Dixon-Woods, M., Fitzpatrick, R., Abrams, K. R., & Jones, D. R. (2002). Factors affecting uptake of childhood immunization: A Bayesian synthesis of qualitative and quantitative evidence. The Lancet, 360 (9345), 1596–1599.

Rycroft-Malone, J., McCormack, B., Hutchinson, A. M., et al. (2012). Realist synthesis: Illustrating the method for implementation research. Implementation Science, 7 , 33. https://doi.org/10.1186/1748-5908-7-33

Sandelowski, M., & Barroso, J. (2007). Handbook for synthesizing qualitative research . Springer Publishing Company.

Sandelowski, M., & Leeman, J. (2012). Writing usable qualitative health research findings. Qualitative Health Research, 22 (10), 1404–1413.

Schutz, A. (1962). Collected papers. Vol. 1. Martinus Nijhoff. 1964. Collected papers 2.

Snyder, H. (2019). Literature review as a research methodology: An overview and guidelines. Journal of Business Research, 104 , 333–339.

Spiegelhalter, D., Myles, J. P., Jones, D. R., & Abrams, K. R. (1999). An introduction to Bayesian methods in health technology assessment. British Medical Journal, 319 (7208), 508.

Stemler, S. (2001). An overview of content analysis. Practical Assessment, Research, and Evaluation, 7 , Article 17.

Strauss, A., & Corbin, J. (1998). Basics of qualitative research: Techniques and procedures for developing grounded theory . Sage.

Stremersch, S., Verniers, I., & Verhoef, P. C. (2007). The quest for citations: Drivers of article impact. Journal of Marketing, 71 (3), 171–193. https://doi.org/10.1509/jmkg.71.3.171

Suikkala, A., & Leino-Kilpi, H. (2000). Nursing student-patient relationships: A review of the literature from 1984–1998. Journal of Advanced Nursing., 2000 (33), 42–50. https://doi.org/10.1046/j.1365-2648.2001.01636.x

Sutton, A. J., & Abrams, K. R. (2001). Bayesian methods in meta-analysis and evidence synthesis. Statistical Methods in Medical Research, 10 (4), 277–303.

Thomas, J., & Harden, A. (2008). Methods for the thematic synthesis of qualitative research in systematic reviews. BMC Medical Research Methodology, 8 (1), 1.

Weed, M. (2005). Meta interpretation: A method for the interpretive synthesis of qualitative research. Forum Qualitative Sozialforschung/Forum: Qualitative Social Research, 6 (1).

Wong, G., MacPhee, M., Merrett, K., Miller, K., Taylor, S., & Pawliuk, C. (2020). The realist review process workshop [presentation]. https://doi.org/10.14288/1.0390457 .

Xiao, Y., & Watson, M. (2019). Guidance on conducting a systematic literature review. Journal of Planning Education and Research, 39 (1), 93–112. https://doi.org/10.1177/0739456X17723971

Zhao, S. (1991). Metatheory, metamethod, meta-data-analysis: What, why and how? Sociological Perspectives, 34 , 377–390.

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Literature Review - what is a Literature Review, why it is important and how it is done

What are literature reviews, goals of literature reviews, types of literature reviews, about this guide/licence.

• Strategies to Find Sources
• Evaluating Literature Reviews and Sources
• Tips for Writing Literature Reviews
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 What is a literature review? "A literature review is an account of what has been published on a topic by accredited scholars and researchers. In writing the literature review, your purpose is to convey to your reader what knowledge and ideas have been established on a topic, and what their strengths and weaknesses are. As a piece of writing, the literature review must be defined by a guiding concept (e.g., your research objective, the problem or issue you are discussing, or your argumentative thesis). It is not just a descriptive list of the material available, or a set of summaries. " - Quote from Taylor, D. (n.d) "The literature review: A few tips on conducting it"

Source NC State University Libraries. This video is published under a Creative Commons 3.0 BY-NC-SA US license.

What are the goals of creating a Literature Review?

• To develop a theory or evaluate an existing theory
• To summarize the historical or existing state of a research topic
• Identify a problem in a field of research 

- Baumeister, R.F. & Leary, M.R. (1997). "Writing narrative literature reviews," Review of General Psychology , 1(3), 311-320.

When do you need to write a Literature Review?

• When writing a prospectus or a thesis/dissertation
• When writing a research paper
• When writing a grant proposal

In all these cases you need to dedicate a chapter in these works to showcase what have been written about your research topic and to point out how your own research will shed a new light into these body of scholarship.

Literature reviews are also written as standalone articles as a way to survey a particular research topic in-depth. This type of literature reviews look at a topic from a historical perspective to see how the understanding of the topic have change through time.

What kinds of literature reviews are written?

• Narrative Review: The purpose of this type of review is to describe the current state of the research on a specific topic/research and to offer a critical analysis of the literature reviewed. Studies are grouped by research/theoretical categories, and themes and trends, strengths and weakness, and gaps are identified. The review ends with a conclusion section which summarizes the findings regarding the state of the research of the specific study, the gaps identify and if applicable, explains how the author's research will address gaps identify in the review and expand the knowledge on the topic reviewed.
• Book review essays/ Historiographical review essays : This is a type of review that focus on a small set of research books on a particular topic " to locate these books within current scholarship, critical methodologies, and approaches" in the field. - LARR
• Systematic review : "The authors of a systematic review use a specific procedure to search the research literature, select the studies to include in their review, and critically evaluate the studies they find." (p. 139). Nelson, L.K. (2013). Research in Communication Sciences and Disorders . San Diego, CA: Plural Publishing.
• Meta-analysis : "Meta-analysis is a method of reviewing research findings in a quantitative fashion by transforming the data from individual studies into what is called an effect size and then pooling and analyzing this information. The basic goal in meta-analysis is to explain why different outcomes have occurred in different studies." (p. 197). Roberts, M.C. & Ilardi, S.S. (2003). Handbook of Research Methods in Clinical Psychology . Malden, MA: Blackwell Pub.
• Meta-synthesis : "Qualitative meta-synthesis is a type of qualitative study that uses as data the findings from other qualitative studies linked by the same or related topic." (p.312). Zimmer, L. (2006). "Qualitative meta-synthesis: A question of dialoguing with texts," Journal of Advanced Nursing , 53(3), 311-318.

Guide adapted from "Literature Review" , a guide developed by Marisol Ramos used under CC BY 4.0 /modified from original.

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Introduction to Literature Reviews

Introduction.

• Step One: Define
• Step Two: Research
• Step Three: Write
• Suggested Readings

A literature review is a written work that :

• Compiles significant research published on a topic by accredited scholars and researchers;
• —Surveys scholarly articles, books, dissertations, conference proceedings, and other sources;
• —Examines contrasting perspectives, theoretical approaches, methodologies, findings, results, conclusions.
• —Reviews critically, analyzes, and synthesizes existing research on a topic; and,
• Performs a thorough “re” view, “overview”, or “look again” of past and current works on a subject, issue, or theory.

From these analyses, the writer then offers an overview of the current status of a particular area of knowledge from both a practical and theoretical perspective.

Literature reviews are important because they are usually a  required  step in a thesis proposal (Master's or PhD). The proposal will not be well-supported without a literature review. Also, literature reviews are important because they help you learn important authors and ideas in your field. This is useful for your coursework and your writing. Knowing key authors also helps you become acquainted with other researchers in your field.

Look at this diagram and imagine that your research is the "something new." This shows how your research should relate to major works and other sources.

Olivia Whitfield | Graduate Reference Assistant | 2012-2015

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Literature Reviews

What is a literature review.

• Getting Started
• Searching the Literature
• How to Read Scholarly Studies
• Managing Your Results
• Assembling Your Review

Jump to Section

• Selecting a Topic & Scope
• Identify Keywords to Use in Searching
• Finding Articles
• Reading, Note-taking, and Organization
• Citation Management

Writing Assistance for Literature Reviews

Introduction.

This guide was designed to explain how to create a literature review step by step. If you have any questions about the content of this guide or would simply like one-on-one help please use the button below to make an appointment with one of the library's research librarians.

Research Help

Set up a consultation with a librarian for help refining your topic and finding sources for your paper.

• Make an Appointment

A literature review is a very specific type of academic project. It is not an annotated bibliography. It isn't a research paper. It isn't a comprehensive list of everything ever published on a certain topic. 

Literature reviews are not created to produce new insights. They are written to explore and explain the literature on the topic or issue. 

One of the most important functions of a literature review is to lay the groundwork, provide background and context, for a larger research project such as a Masters thesis or PhD dissertation. Literature reviews often come at the start of scholarly journal articles. In the social sciences and natural sciences, a literature review comprises a section of a scholarly journal article.

Professors in research methods courses often assign standalone literature reviews so that students develop skills in searching, analyzing and organizing scholarly literature in a particular field. 

1. Selecting a Topic & Scope

The first step in any literature review is to identify a topic or subject area you wish to explore, and then setting some parameters to find the scope of your review.

You also need to make sure you select a subject area that has already been researched . It will not be possible to locate sufficient existing literature on a brand new discovery or current event that is being written about in the news right now. It needs to be a well-established research area with existing studies you can review, organize and analyze. Some professors require you to find a topic that has 'not been researched before'. In that case, they don't mean an entire broad topic that hasn't been researched; instead, you'll want to find a sliver of a broad topic that hasn't been researched before. This is where narrowing your topic and finding parameters becomes very important. You may need to do some background reading on several different topics to find one that works, if your professor is having you do a standalone literature review as part of a research methods course.

Ways of Narrowing a Broad topic

For example:

Broad topic: ADHD treatments

Narrowed question: How can neurofeedback be used in threating elementary school-aged children?

Publication Dates

The scope of your review will be a part of refining your topic area or research question. In some disciplines, medicine and health science for example, the publication date of your sources may be extremely important. So, to avoid including outdated clinical recommendations, you may want to limit your review to only the most recent research out there. For other topics, say history or literature, publication date may not be as important - and scholarly research from 20, 30, even 50 years ago may still be relevant and useful today. So it's good idea to consider setting some date ranges for your search, it that is important to your topic.

Whatever your topic area turns out to be, framing the boundaries of your research question ahead of time will make searching and selecting appropriate articles that much easier. 

2. Identify Keywords to Use in Searching

Once you have defined a suitable topic or research question for your review, you will need to create a list of keywords that you will use to search for appropriate studies to include in your review. You will be doing searches through several different databases, Google scholar, or publisher platforms and the terminology used in each may vary. It is especially important to have a good variety of search terms that you can combine in different ways. This will ensure you gather the most relevant sources that cover your topic thoroughly. 

Remember to continue to gather and change your keywords as you read more about your topic!

To start, list synonyms and phrases that have to do with the main words of a research topic:

Example: Is neurofeedback useful in the treatment of ADHD in children?

Now, let's consider the word "useful" in this example topic. What is meant by "useful"? The word itself will not be helpful while searching. Instead, think about what might be useful  in terms of treatment of a child with ADHD. Think about benefits and outcomes and brainstorm a list of words:

3. Finding Articles

Using research guides to find subject specific databases.

For more focused searching of the literature of just one discipline, head over to the Research Guides section of our website. We have  Subject Guides   for all disciplines represented at UTC. Find the subject guide that has most to do with your topic, for example, if you are writing about politics, you'd choose Political Science and Public Service guide. Writing about K-12 schools? Choose Education. Each Subject Guide was created by UTC Librarians and has links to a variety of resources that you have access to.

The databases listed are smaller, specialized search engines that mainly retrieve scholarly articles. You will usually find smaller sets of results for each search you do, but those results will be from a subset of very focused resources.

Subject specific databases are searchable by keywords just like Quick Search. An example is shown in the screenshot below of the APA PsycINFO database using the keywords "neurofeedback therapy" AND "ADHD in children":

APA PsycInfo Database Search:

Using the Quick Search

Quick Search is the main search box located in the center of the Library home page. It covers all formats within our collection (physical and electronic, books, films, articles and more).and all subject areas. It is an excellent tool for locating and accessing scholarly content using keyword searches. Below is an example of how to enter your keywords for an effective search, for our sample topic we typed the words "neurofeedback ADHD children behavior problems":

Quick Search has filters  to narrow to just peer reviewed if you'd like, or you can narrow to a specific format like articles, books, or ebooks. You can also narrow by date. Look for the filters on the left sidebar after you run a search. 

As you browse results. you will notice links below each article that allow you to read the full text on the publisher website. If you decide you would like to use the article in your lit review, download the entire PDF to your device for later use. 

Using Google Scholar

Click the  Databases button (just below the Quick Search box on library's homepage) and look for Google Scholar under Multisubject Databases. Using Google Scholar through the UTC Library links our library subscriptions to your Google Scholar search results- which allows you to see articles with no paywalls if we have access! 

4. Reading, Note-taking, and Organization

1. review the how to read a scholarly article guide.

• Learn about common sections in science and social science articles
• Strategies and tips for reading start by reading the entire Abstract, and feel free to jump down to Discussion to decide if an article should be included in your paper

2. Save yourself time with good note-taking

As you read each study, take notes about the most important findings, key concepts, debates or areas of controversy and common themes you see. These notes will inform how you approach organizing and writing your literature review.

To keep organized, UTC Librarians recommend using a literature review matrix, or spreadsheet, to keep track of the articles you find as you go.  Add columns for the citation (including the URL of the article), and once you read it, track the authors' research question, methods, findings and themes. Importantly, keep track of notes and quotes as you go, and the page numbers you got them from. You will see themes or facts emerge as you read more and more articles. 

Here's an example Literature Review Matrix for you to view. Download a sample matrix as an Excel file and edit with your own sources.

3. Some ideas on how to compile an outline for your review:

After reading and taking notes on the sources you are including in your literature review, you will probably be able to identify common themes or threads that appear throughout. These recurring threads or themes can be very useful in creating a narrative framework for your review to make it easier for your readers to understand what literature exists, what has been learned, and why it is significant. Using our example of Neurofeedback Therapy for Children with ADHD, we might decide to organize our results something like this:

Other questions you might ask yourself as you decide how to outline your literature review: 

• What are the major claims being made about the topic? (There may be several)
• What significant data exists to support / explain the claims?
• Are there connections between the claims / concepts / evidence?
• Are there controversies in the literature? 
• Are there knowledge gaps that have yet to be explored? 

5. Citation Management

For smaller literature review projects, simply keeping a list of your references in Word or Google Docs is probably fine. But for longer projects, or those that are going to form the basis for a thesis or dissertation, many students choose to use citation management software to keep track of, organize, and format their references. The UTC Library supports two main citation management options: Zotero and EndNote. 

Zotero is an open source tool provided by Google. It works well with Chrome and Google Docs and has a really nice, easy to use Chrome extension that allows you to seamlessly add references and full text PDFs to your reference "library" as you do your research. The Library has a guide page that walks you through the basics of downloading, configuring and using Zotero. Visit the link below to get started. 

Zotero Guide Page

EndNote is a very powerful software package with lots of advanced features. It is produced by a commercial publisher and the Library pays a subscription fee to offer it to our students and faculty. It comes in two versions: desktop and cloud-based. (The two versions work together to provide seamless access and redundancy no matter where you are). EndNote can be very labor intensive to configure and use at the beginning, but it offers hundreds of citation styles (most major journals, academic associations and scholarly publishers) and works very well for longer, more complex projects with many references and citations. It integrates really well with Microsoft Word but does not work as well with Google Docs. The Library has basic information on its website about how to download and set up EndNote, but in order to learn it effectively, a workshop or librarian consultation is usually required. Our EndNote information is found a the link below:

EndNote Help Page

The UTC Library is home to a full-service Writing and Communication Center with tutors available to assist you with writing projects at any stage - from outline, to draft, to final manuscript. The WCC has it's own section of the UTC Library website. Check out the link below to learn more about the services they offer and how to go about scheduling an appointment.

UTC Writing and Communication Center

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Literature Review: The What, Why and How-to Guide: Literature Reviews?

• Literature Reviews?
• Strategies to Finding Sources
• Keeping up with Research!
• Evaluating Sources & Literature Reviews
• Organizing for Writing
• Writing Literature Review
• Other Academic Writings

What is a Literature Review?

So, what is a literature review .

"A literature review is an account of what has been published on a topic by accredited scholars and researchers. In writing the literature review, your purpose is to convey to your reader what knowledge and ideas have been established on a topic, and what their strengths and weaknesses are. As a piece of writing, the literature review must be defined by a guiding concept (e.g., your research objective, the problem or issue you are discussing, or your argumentative thesis). It is not just a descriptive list of the material available or a set of summaries." - Quote from Taylor, D. (n.d)."The Literature Review: A Few Tips on Conducting it".

• Citation: "The Literature Review: A Few Tips on Conducting it"

What kinds of literature reviews are written?

Each field has a particular way to do reviews for academic research literature. In the social sciences and humanities the most common are:

• Narrative Reviews: The purpose of this type of review is to describe the current state of the research on a specific research topic and to offer a critical analysis of the literature reviewed. Studies are grouped by research/theoretical categories, and themes and trends, strengths and weaknesses, and gaps are identified. The review ends with a conclusion section that summarizes the findings regarding the state of the research of the specific study, the gaps identify and if applicable, explains how the author's research will address gaps identify in the review and expand the knowledge on the topic reviewed.
• Book review essays/ Historiographical review essays : A type of literature review typical in History and related fields, e.g., Latin American studies. For example, the Latin American Research Review explains that the purpose of this type of review is to “(1) to familiarize readers with the subject, approach, arguments, and conclusions found in a group of books whose common focus is a historical period; a country or region within Latin America; or a practice, development, or issue of interest to specialists and others; (2) to locate these books within current scholarship, critical methodologies, and approaches; and (3) to probe the relation of these new books to previous work on the subject, especially canonical texts. Unlike individual book reviews, the cluster reviews found in LARR seek to address the state of the field or discipline and not solely the works at issue.” - LARR

What are the Goals of Creating a Literature Review?

• To develop a theory or evaluate an existing theory
• To summarize the historical or existing state of a research topic
• Identify a problem in a field of research 
• Baumeister, R.F. & Leary, M.R. (1997). "Writing narrative literature reviews," Review of General Psychology , 1(3), 311-320.

When do you need to write a Literature Review?

• When writing a prospectus or a thesis/dissertation
• When writing a research paper
• When writing a grant proposal

In all these cases you need to dedicate a chapter in these works to showcase what has been written about your research topic and to point out how your own research will shed new light into a body of scholarship.

Where I can find examples of Literature Reviews?

Note:  In the humanities, even if they don't use the term "literature review", they may have a dedicated  chapter that reviewed the "critical bibliography" or they incorporated that review in the introduction or first chapter of the dissertation, book, or article.

• UCSB electronic theses and dissertations In partnership with the Graduate Division, the UC Santa Barbara Library is making available theses and dissertations produced by UCSB students. Currently included in ADRL are theses and dissertations that were originally filed electronically, starting in 2011. In future phases of ADRL, all theses and dissertations created by UCSB students may be digitized and made available.

Where to Find Standalone Literature Reviews

Literature reviews are also written as standalone articles as a way to survey a particular research topic in-depth. This type of literature review looks at a topic from a historical perspective to see how the understanding of the topic has changed over time. 

• Find e-Journals for Standalone Literature Reviews The best way to get familiar with and to learn how to write literature reviews is by reading them. You can use our Journal Search option to find journals that specialize in publishing literature reviews from major disciplines like anthropology, sociology, etc. Usually these titles are called, "Annual Review of [discipline name] OR [Discipline name] Review. This option works best if you know the title of the publication you are looking for. Below are some examples of these journals! more... less... Journal Search can be found by hovering over the link for Research on the library website.

Social Sciences

• Annual Review of Anthropology
• Annual Review of Political Science
• Annual Review of Sociology
• Ethnic Studies Review

Hard science and health sciences:

• Annual Review of Biomedical Data Science
• Annual Review of Materials Science
• Systematic Review From journal site: "The journal Systematic Reviews encompasses all aspects of the design, conduct, and reporting of systematic reviews" in the health sciences.
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Literature Review: Purpose of a Literature Review

• Literature Review
• Purpose of a Literature Review
• Work in Progress
• Compiling & Writing
• Books, Articles, & Web Pages
• Types of Literature Reviews
• Departmental Differences
• Citation Styles & Plagiarism
• Know the Difference! Systematic Review vs. Literature Review

The purpose of a literature review is to:

• Provide a foundation of knowledge on a topic
• Identify areas of prior scholarship to prevent duplication and give credit to other researchers
• Identify inconstancies: gaps in research, conflicts in previous studies, open questions left from other research
• Identify the need for additional research (justifying your research)
• Identify the relationship of works in the context of their contribution to the topic and other works
• Place your own research within the context of existing literature, making a case for why further study is needed.

Videos & Tutorials

VIDEO: What is the role of a literature review in research? What's it mean to "review" the literature? Get the big picture of what to expect as part of the process. This video is published under a Creative Commons 3.0 BY-NC-SA US license. License, credits, and contact information can be found here: https://www.lib.ncsu.edu/tutorials/litreview/

Elements in a Literature Review

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What Is A Literature Review?

A plain-language explainer (with examples).

By:  Derek Jansen (MBA) & Kerryn Warren (PhD) | June 2020 (Updated May 2023)

If you’re faced with writing a dissertation or thesis, chances are you’ve encountered the term “literature review” . If you’re on this page, you’re probably not 100% what the literature review is all about. The good news is that you’ve come to the right place.

Literature Review 101

• What (exactly) is a literature review
• What’s the purpose of the literature review chapter
• How to find high-quality resources
• How to structure your literature review chapter
• Example of an actual literature review

What is a literature review?

The word “literature review” can refer to two related things that are part of the broader literature review process. The first is the task of  reviewing the literature  – i.e. sourcing and reading through the existing research relating to your research topic. The second is the  actual chapter  that you write up in your dissertation, thesis or research project. Let’s look at each of them:

Reviewing the literature

The first step of any literature review is to hunt down and  read through the existing research  that’s relevant to your research topic. To do this, you’ll use a combination of tools (we’ll discuss some of these later) to find journal articles, books, ebooks, research reports, dissertations, theses and any other credible sources of information that relate to your topic. You’ll then  summarise and catalogue these  for easy reference when you write up your literature review chapter. 

The literature review chapter

The second step of the literature review is to write the actual literature review chapter (this is usually the second chapter in a typical dissertation or thesis structure ). At the simplest level, the literature review chapter is an  overview of the key literature  that’s relevant to your research topic. This chapter should provide a smooth-flowing discussion of what research has already been done, what is known, what is unknown and what is contested in relation to your research topic. So, you can think of it as an  integrated review of the state of knowledge  around your research topic. 

What’s the purpose of a literature review?

The literature review chapter has a few important functions within your dissertation, thesis or research project. Let’s take a look at these:

Purpose #1 – Demonstrate your topic knowledge

The first function of the literature review chapter is, quite simply, to show the reader (or marker) that you  know what you’re talking about . In other words, a good literature review chapter demonstrates that you’ve read the relevant existing research and understand what’s going on – who’s said what, what’s agreed upon, disagreed upon and so on. This needs to be  more than just a summary  of who said what – it needs to integrate the existing research to  show how it all fits together  and what’s missing (which leads us to purpose #2, next). 

Purpose #2 – Reveal the research gap that you’ll fill

The second function of the literature review chapter is to  show what’s currently missing  from the existing research, to lay the foundation for your own research topic. In other words, your literature review chapter needs to show that there are currently “missing pieces” in terms of the bigger puzzle, and that  your study will fill one of those research gaps . By doing this, you are showing that your research topic is original and will help contribute to the body of knowledge. In other words, the literature review helps justify your research topic.  

Purpose #3 – Lay the foundation for your conceptual framework

The third function of the literature review is to form the  basis for a conceptual framework . Not every research topic will necessarily have a conceptual framework, but if your topic does require one, it needs to be rooted in your literature review. 

For example, let’s say your research aims to identify the drivers of a certain outcome – the factors which contribute to burnout in office workers. In this case, you’d likely develop a conceptual framework which details the potential factors (e.g. long hours, excessive stress, etc), as well as the outcome (burnout). Those factors would need to emerge from the literature review chapter – they can’t just come from your gut! 

So, in this case, the literature review chapter would uncover each of the potential factors (based on previous studies about burnout), which would then be modelled into a framework. 

Purpose #4 – To inform your methodology

The fourth function of the literature review is to  inform the choice of methodology  for your own research. As we’ve  discussed on the Grad Coach blog , your choice of methodology will be heavily influenced by your research aims, objectives and questions . Given that you’ll be reviewing studies covering a topic close to yours, it makes sense that you could learn a lot from their (well-considered) methodologies.

So, when you’re reviewing the literature, you’ll need to  pay close attention to the research design , methodology and methods used in similar studies, and use these to inform your methodology. Quite often, you’ll be able to  “borrow” from previous studies . This is especially true for quantitative studies , as you can use previously tried and tested measures and scales. 

How do I find articles for my literature review?

Finding quality journal articles is essential to crafting a rock-solid literature review. As you probably already know, not all research is created equally, and so you need to make sure that your literature review is  built on credible research . 

We could write an entire post on how to find quality literature (actually, we have ), but a good starting point is Google Scholar . Google Scholar is essentially the academic equivalent of Google, using Google’s powerful search capabilities to find relevant journal articles and reports. It certainly doesn’t cover every possible resource, but it’s a very useful way to get started on your literature review journey, as it will very quickly give you a good indication of what the  most popular pieces of research  are in your field.

One downside of Google Scholar is that it’s merely a search engine – that is, it lists the articles, but oftentimes  it doesn’t host the articles . So you’ll often hit a paywall when clicking through to journal websites. 

Thankfully, your university should provide you with access to their library, so you can find the article titles using Google Scholar and then search for them by name in your university’s online library. Your university may also provide you with access to  ResearchGate , which is another great source for existing research. 

Remember, the correct search keywords will be super important to get the right information from the start. So, pay close attention to the keywords used in the journal articles you read and use those keywords to search for more articles. If you can’t find a spoon in the kitchen, you haven’t looked in the right drawer. 

Need a helping hand?

How should I structure my literature review?

Unfortunately, there’s no generic universal answer for this one. The structure of your literature review will depend largely on your topic area and your research aims and objectives.

You could potentially structure your literature review chapter according to theme, group, variables , chronologically or per concepts in your field of research. We explain the main approaches to structuring your literature review here . You can also download a copy of our free literature review template to help you establish an initial structure.

In general, it’s also a good idea to start wide (i.e. the big-picture-level) and then narrow down, ending your literature review close to your research questions . However, there’s no universal one “right way” to structure your literature review. The most important thing is not to discuss your sources one after the other like a list – as we touched on earlier, your literature review needs to synthesise the research , not summarise it .

Ultimately, you need to craft your literature review so that it conveys the most important information effectively – it needs to tell a logical story in a digestible way. It’s no use starting off with highly technical terms and then only explaining what these terms mean later. Always assume your reader is not a subject matter expert and hold their hand through a journe y of the literature while keeping the functions of the literature review chapter (which we discussed earlier) front of mind.

Example of a literature review

In the video below, we walk you through a high-quality literature review from a dissertation that earned full distinction. This will give you a clearer view of what a strong literature review looks like in practice and hopefully provide some inspiration for your own. 

Wrapping Up

In this post, we’ve (hopefully) answered the question, “ what is a literature review? “. We’ve also considered the purpose and functions of the literature review, as well as how to find literature and how to structure the literature review chapter. If you’re keen to learn more, check out the literature review section of the Grad Coach blog , as well as our detailed video post covering how to write a literature review . 

Psst… there’s more!

This post is an extract from our bestselling short course, Literature Review Bootcamp . If you want to work smart, you don't want to miss this .

16 Comments

Thanks for this review. It narrates what’s not been taught as tutors are always in a early to finish their classes.

Thanks for the kind words, Becky. Good luck with your literature review 🙂

This website is amazing, it really helps break everything down. Thank you, I would have been lost without it.

This is review is amazing. I benefited from it a lot and hope others visiting this website will benefit too.

Timothy T. Chol [email protected]

Thank you very much for the guiding in literature review I learn and benefited a lot this make my journey smooth I’ll recommend this site to my friends

This was so useful. Thank you so much.

Hi, Concept was explained nicely by both of you. Thanks a lot for sharing it. It will surely help research scholars to start their Research Journey.

The review is really helpful to me especially during this period of covid-19 pandemic when most universities in my country only offer online classes. Great stuff

Great Brief Explanation, thanks

So helpful to me as a student

GradCoach is a fantastic site with brilliant and modern minds behind it.. I spent weeks decoding the substantial academic Jargon and grounding my initial steps on the research process, which could be shortened to a couple of days through the Gradcoach. Thanks again!

This is an amazing talk. I paved way for myself as a researcher. Thank you GradCoach!

Well-presented overview of the literature!

This was brilliant. So clear. Thank you

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What is a literature review?

A literature review is a critical analysis of the literature related to your research topic. It evaluates and critiques the literature to establish a theoretical framework for your research topic and/or identify a gap in the existing research that your research will address.

A literature review is not a summary of the literature. You need to engage deeply and critically with the literature. Your literature review should show your understanding of the literature related to your research topic and lead to presenting a rationale for your research.

A literature review focuses on:

• the context of the topic
• key concepts, ideas, theories and methodologies
• key researchers, texts and seminal works
• major issues and debates
• identifying conflicting evidence
• the main questions that have been asked around the topic
• the organisation of knowledge on the topic
• definitions, particularly those that are contested
• showing how your research will advance scholarly knowledge (generally referred to as identifying the ‘gap’).

This module will guide you through the functions of a literature review; the typical process of conducting a literature review (including searching for literature and taking notes); structuring your literature review within your thesis and organising its internal ideas; and styling the language of your literature review.

The purposes of a literature review

A literature review serves two main purposes:

1) To show awareness of the present state of knowledge in a particular field, including:

• seminal authors
• the main empirical research
• theoretical positions
• controversies
• breakthroughs as well as links to other related areas of knowledge.

2) To provide a foundation for the author’s research. To do that, the literature review needs to:

• help the researcher define a hypothesis or a research question, and how answering the question will contribute to the body of knowledge;
• provide a rationale for investigating the problem and the selected methodology;
• provide a particular theoretical lens, support the argument, or identify gaps.

Before you engage further with this module, try the quiz below to see how much you already know about literature reviews.

Research and Writing Skills for Academic and Graduate Researchers Copyright © 2022 by RMIT University is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License , except where otherwise noted.

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The literature review structure and function

Part 4: Chapter 14

Questions to consider

A. Why is a literature review also referred to as the background or introduction of a paper?

B. What are the functions of a literature review?

C. What is the primary objective of a literature review?

No matter how the literature review is organized (e.g. chronologically, thematically), it follows a standard format: introduction, body, conclusion.  The introduction to the literature review contains a statement or statements about the overall topic of consideration. This might be a paragraph or section that lets the reader know what the literature review will address. Occasionally, writers describe how the literature review will be organized (for example, what main points are going to be dealt with and in what order). Like a methods section, search criteria (keywords, databases, journals) are sometimes identified this section; they may be discussed in the conclusion as well or not attended to.

An introduction to an introduction

The purpose of the introduction to the literature review is to lead the reader through the body and the main points to the ultimate message of the work. The introduction will achieve several goals.

• Define or identify the general topic, issue, or area of concern thereby providing an appropriate context and a historical frame of reference for the remainder of the review.
• Indicate overall trends in what has been previously published on the topic; refer to a landmark or seminal study; or reveal conflicts in theory, methodology, evidence, conclusions, or gaps in research and scholarship.
• Establish the objective for reviewing this research (point of view); explain the criteria used to select the reviewed material; the organization of the review (sequence); and – if necessary – why certain literature either is or is not included (scope).
• Demonstrate how ensuing research either closes a gap in the literature, extends earlier work, or replicates an important study thereby contributing new knowledge to the field.

The body of the literature review

Written information is commonly presented logically, from general to specific, showing how past research relates to a proposed project (for literature reviews that serve as the background or introduction to a research proposal or paper).  Information should be deliberately organized following an obvious progression of ideas (e.g. chronologically, following the development of a research topic) with consistent support from acceptable sources.

This is where a strong synthesis works to illustrate the value of the writer’s contribution and to persuade the reader. To that end, citing two or more sources for a single point demonstrates its strength or general acceptability.

The use of a formal academic voice should be consistently maintained, and the content should be  focused and objective. Author contribution should illustrate important strengths and weaknesses of research studies as well as contradictions and inconsistent findings. Implications and suggestions for further research, or where there are gaps in the current literature, should be specific, original and a logical conclusion based on the sources deployed as evidence.

Strong conclusions

The conclusion often summarizes the major points of the literature review, discusses implications, and reveals an area for future or further research needed. This is where the proportion of writer contribution is often higher and there is relatively less cited source material.

The conclusion will often

• clearly define the topic or issue for an informed audience;
• provide a complete and exhaustive overview of relevant literature;
• be focused throughout;
• critically and consistently evaluate and synthesize extant information;
• present information logically and accurately;
• be relevant and objective; and
• accurately cite all references using one citation style or system.

Documenting the support

The reference list of publications used in a literature review serves two purposes. First, it provides the reader with a means to evaluate the quality of the research. Second, accurately and correctly citing all the sources used protects the author from possible accusations of plagiarism. Using the words or ideas of others without referencing the source is a very serious academic offense.

The reference list reflects the thoroughness of the review. It also allows others to retrieve the cited publications. Errors made in authors’ names, journal or article titles, page numbers and dates present barriers to retrieval of articles and prevent attributing credit to authors for their work. Each reference should be checked carefully for errors. Every in-text citation must have a listing in the references and every title in the reference list should connect to an in-text citation. [1]

Exercise #1

Read the following brief literature review from Attending lectures in person, hybrid or online—how do students choose, and what about the outcome? and complete an simple inventory of it by answering these questions:

• What is the topic and how is it relevant?
• How many unique sources are used?
• How many citations are there?
• What ideas do the authors contribute on this topic?
• What can readers expect from the rest of the article?

Introduction 1 The COVID-19 pandemic has occasionally been viewed as one of the biggest experiments in education (Tomas & Rogers, 2020; Dunrong & Jin, 2020).  2 This might be a misnomer, since “experiment” implies some sort of controlled conditions, while arguably, educational settings were largely controlled by fluctuating, external factors.  3 “Disruption” might be a more fitting characterization of what was essentially an emergency response, and in the aftermath of this disruption, increased flexibility in attendance and delivery modes of education will become the “new normal” (Kortemeyer, 2020; Schapiro, 2021; Hofer et al., 2021). 4 The educational experiment starts now, as the impact of this flexibility can be investigated in more controlled settings. 5 A preliminary “finding” of this experiment is that many faculty members report that live-lecture attendance has decreased—some faculty members even go so far as to demand that streaming, video conferencing, and recording should be discontinued, “now that the pandemic is over,” to force students to return to campus. 6 There might be some justification for that: both students and faculty who knew the university before COVID-19 bemoan the loss of campus culture, and there are certainly cross-disciplinary and social competencies that were implicit in higher education, such as scientific discourse, self-presentation, teamwork, conflict resolution, etc., which may not be fostered anymore when purely focusing on the explicit curriculum of teaching and transmitting facts, methods, and concepts. 7 There are also serious concerns about loneliness, depression, anxiety, and procrastination that need to be addressed (Wang et al., 2020; Pelikan et al., 2021; Copeland et al., 2021; Tasso et al., 2021; Amendola et al., 2021; Buizza et al., 2022), which are consistent with a survey on student well-being conducted at ETH Zurich at the height of the pandemic. 8 The problems and their solutions are likely more complex and reaching deeper—the pandemic may have simply brought some existing inconsistencies in the 21st-century higher-education system to the surface, particularly when it comes to lecturing (Vlachopoulos & Jan, 2020). 9 An immediate question is how student choices regarding attendance may have influenced performance in the subsequent exam session. 10 Finally, throughout the whole pandemic, high-stake exams were conducted in-person on-site at ETH Zurich, and another question is how the students’ perception of these physical exam settings may be connected to their potentially completely virtual attendance during the learning phase. [2]

Review and Reinforce

The goal of the literature review is to present an argument defending the relevance and value of a research question. To that end, a literature review must be balanced. For example, in proposing a new theory, both findings that are consistent with that theory and contradictory evidence must be discussed. It is acceptable to argue that the balance of the research supports the existence of a phenomenon or is consistent with a theory, but it is not acceptable to ignore contradictory evidence. What makes a research question interesting is often the uncertainty about its answer.

Media Attributions

• activist art © Ron Cogswell is licensed under a CC BY (Attribution) license
• Adapted from Frederiksen, L., & Phelps, S. F. (2017). Literature Reviews for Education and Nursing Graduate Students. Open Textbook Library. ↵
• Kortemeyer, G., Dittmann-Domenichini, N., Schlienger, C., Spilling, E., Yaroshchuk, A., & Dissertori, G. (2023). Attending lectures in person, hybrid or online—how do students choose, and what about the outcome?: Revista de Universidad y Sociedad del Conocimiento. International Journal of Educational Technology in Higher Education , 20(1), 19. https://doi.org/10.1186/s41239-023-00387-5. ↵

Sourcing, summarizing, and synthesizing:  Skills for effective research writing  Copyright © 2023 by Wendy L. McBride is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License , except where otherwise noted.

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A literature review surveys prior research published in books, scholarly articles, and any other sources relevant to a particular issue, area of research, or theory, and by so doing, provides a description, summary, and critical evaluation of these works in relation to the research problem being investigated. Literature reviews are designed to provide an overview of sources you have used in researching a particular topic and to demonstrate to your readers how your research fits within existing scholarship about the topic.

Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper . Fourth edition. Thousand Oaks, CA: SAGE, 2014.

Importance of a Good Literature Review

A literature review may consist of simply a summary of key sources, but in the social sciences, a literature review usually has an organizational pattern and combines both summary and synthesis, often within specific conceptual categories . A summary is a recap of the important information of the source, but a synthesis is a re-organization, or a reshuffling, of that information in a way that informs how you are planning to investigate a research problem. The analytical features of a literature review might:

• Give a new interpretation of old material or combine new with old interpretations,
• Trace the intellectual progression of the field, including major debates,
• Depending on the situation, evaluate the sources and advise the reader on the most pertinent or relevant research, or
• Usually in the conclusion of a literature review, identify where gaps exist in how a problem has been researched to date.

Given this, the purpose of a literature review is to:

• Place each work in the context of its contribution to understanding the research problem being studied.
• Describe the relationship of each work to the others under consideration.
• Identify new ways to interpret prior research.
• Reveal any gaps that exist in the literature.
• Resolve conflicts amongst seemingly contradictory previous studies.
• Identify areas of prior scholarship to prevent duplication of effort.
• Point the way in fulfilling a need for additional research.
• Locate your own research within the context of existing literature [very important].

Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper. 2nd ed. Thousand Oaks, CA: Sage, 2005; Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1998; Jesson, Jill. Doing Your Literature Review: Traditional and Systematic Techniques . Los Angeles, CA: SAGE, 2011; Knopf, Jeffrey W. "Doing a Literature Review." PS: Political Science and Politics 39 (January 2006): 127-132; Ridley, Diana. The Literature Review: A Step-by-Step Guide for Students . 2nd ed. Los Angeles, CA: SAGE, 2012.

Types of Literature Reviews

It is important to think of knowledge in a given field as consisting of three layers. First, there are the primary studies that researchers conduct and publish. Second are the reviews of those studies that summarize and offer new interpretations built from and often extending beyond the primary studies. Third, there are the perceptions, conclusions, opinion, and interpretations that are shared informally among scholars that become part of the body of epistemological traditions within the field.

In composing a literature review, it is important to note that it is often this third layer of knowledge that is cited as "true" even though it often has only a loose relationship to the primary studies and secondary literature reviews. Given this, while literature reviews are designed to provide an overview and synthesis of pertinent sources you have explored, there are a number of approaches you could adopt depending upon the type of analysis underpinning your study.

Argumentative Review This form examines literature selectively in order to support or refute an argument, deeply embedded assumption, or philosophical problem already established in the literature. The purpose is to develop a body of literature that establishes a contrarian viewpoint. Given the value-laden nature of some social science research [e.g., educational reform; immigration control], argumentative approaches to analyzing the literature can be a legitimate and important form of discourse. However, note that they can also introduce problems of bias when they are used to make summary claims of the sort found in systematic reviews [see below].

Integrative Review Considered a form of research that reviews, critiques, and synthesizes representative literature on a topic in an integrated way such that new frameworks and perspectives on the topic are generated. The body of literature includes all studies that address related or identical hypotheses or research problems. A well-done integrative review meets the same standards as primary research in regard to clarity, rigor, and replication. This is the most common form of review in the social sciences.

Historical Review Few things rest in isolation from historical precedent. Historical literature reviews focus on examining research throughout a period of time, often starting with the first time an issue, concept, theory, phenomena emerged in the literature, then tracing its evolution within the scholarship of a discipline. The purpose is to place research in a historical context to show familiarity with state-of-the-art developments and to identify the likely directions for future research.

Methodological Review A review does not always focus on what someone said [findings], but how they came about saying what they say [method of analysis]. Reviewing methods of analysis provides a framework of understanding at different levels [i.e. those of theory, substantive fields, research approaches, and data collection and analysis techniques], how researchers draw upon a wide variety of knowledge ranging from the conceptual level to practical documents for use in fieldwork in the areas of ontological and epistemological consideration, quantitative and qualitative integration, sampling, interviewing, data collection, and data analysis. This approach helps highlight ethical issues which you should be aware of and consider as you go through your own study.

Systematic Review This form consists of an overview of existing evidence pertinent to a clearly formulated research question, which uses pre-specified and standardized methods to identify and critically appraise relevant research, and to collect, report, and analyze data from the studies that are included in the review. The goal is to deliberately document, critically evaluate, and summarize scientifically all of the research about a clearly defined research problem . Typically it focuses on a very specific empirical question, often posed in a cause-and-effect form, such as "To what extent does A contribute to B?" This type of literature review is primarily applied to examining prior research studies in clinical medicine and allied health fields, but it is increasingly being used in the social sciences.

Theoretical Review The purpose of this form is to examine the corpus of theory that has accumulated in regard to an issue, concept, theory, phenomena. The theoretical literature review helps to establish what theories already exist, the relationships between them, to what degree the existing theories have been investigated, and to develop new hypotheses to be tested. Often this form is used to help establish a lack of appropriate theories or reveal that current theories are inadequate for explaining new or emerging research problems. The unit of analysis can focus on a theoretical concept or a whole theory or framework.

NOTE: Most often the literature review will incorporate some combination of types. For example, a review that examines literature supporting or refuting an argument, assumption, or philosophical problem related to the research problem will also need to include writing supported by sources that establish the history of these arguments in the literature.

Baumeister, Roy F. and Mark R. Leary. "Writing Narrative Literature Reviews."  Review of General Psychology 1 (September 1997): 311-320; Mark R. Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper . 2nd ed. Thousand Oaks, CA: Sage, 2005; Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1998; Kennedy, Mary M. "Defining a Literature." Educational Researcher 36 (April 2007): 139-147; Petticrew, Mark and Helen Roberts. Systematic Reviews in the Social Sciences: A Practical Guide . Malden, MA: Blackwell Publishers, 2006; Torracro, Richard. "Writing Integrative Literature Reviews: Guidelines and Examples." Human Resource Development Review 4 (September 2005): 356-367; Rocco, Tonette S. and Maria S. Plakhotnik. "Literature Reviews, Conceptual Frameworks, and Theoretical Frameworks: Terms, Functions, and Distinctions." Human Ressource Development Review 8 (March 2008): 120-130; Sutton, Anthea. Systematic Approaches to a Successful Literature Review . Los Angeles, CA: Sage Publications, 2016.

Structure and Writing Style

I.  Thinking About Your Literature Review

The structure of a literature review should include the following in support of understanding the research problem :

• An overview of the subject, issue, or theory under consideration, along with the objectives of the literature review,
• Division of works under review into themes or categories [e.g. works that support a particular position, those against, and those offering alternative approaches entirely],
• An explanation of how each work is similar to and how it varies from the others,
• Conclusions as to which pieces are best considered in their argument, are most convincing of their opinions, and make the greatest contribution to the understanding and development of their area of research.

The critical evaluation of each work should consider :

• Provenance -- what are the author's credentials? Are the author's arguments supported by evidence [e.g. primary historical material, case studies, narratives, statistics, recent scientific findings]?
• Methodology -- were the techniques used to identify, gather, and analyze the data appropriate to addressing the research problem? Was the sample size appropriate? Were the results effectively interpreted and reported?
• Objectivity -- is the author's perspective even-handed or prejudicial? Is contrary data considered or is certain pertinent information ignored to prove the author's point?
• Persuasiveness -- which of the author's theses are most convincing or least convincing?
• Validity -- are the author's arguments and conclusions convincing? Does the work ultimately contribute in any significant way to an understanding of the subject?

II.  Development of the Literature Review

Four Basic Stages of Writing 1.  Problem formulation -- which topic or field is being examined and what are its component issues? 2.  Literature search -- finding materials relevant to the subject being explored. 3.  Data evaluation -- determining which literature makes a significant contribution to the understanding of the topic. 4.  Analysis and interpretation -- discussing the findings and conclusions of pertinent literature.

Consider the following issues before writing the literature review: Clarify If your assignment is not specific about what form your literature review should take, seek clarification from your professor by asking these questions: 1.  Roughly how many sources would be appropriate to include? 2.  What types of sources should I review (books, journal articles, websites; scholarly versus popular sources)? 3.  Should I summarize, synthesize, or critique sources by discussing a common theme or issue? 4.  Should I evaluate the sources in any way beyond evaluating how they relate to understanding the research problem? 5.  Should I provide subheadings and other background information, such as definitions and/or a history? Find Models Use the exercise of reviewing the literature to examine how authors in your discipline or area of interest have composed their literature review sections. Read them to get a sense of the types of themes you might want to look for in your own research or to identify ways to organize your final review. The bibliography or reference section of sources you've already read, such as required readings in the course syllabus, are also excellent entry points into your own research. Narrow the Topic The narrower your topic, the easier it will be to limit the number of sources you need to read in order to obtain a good survey of relevant resources. Your professor will probably not expect you to read everything that's available about the topic, but you'll make the act of reviewing easier if you first limit scope of the research problem. A good strategy is to begin by searching the USC Libraries Catalog for recent books about the topic and review the table of contents for chapters that focuses on specific issues. You can also review the indexes of books to find references to specific issues that can serve as the focus of your research. For example, a book surveying the history of the Israeli-Palestinian conflict may include a chapter on the role Egypt has played in mediating the conflict, or look in the index for the pages where Egypt is mentioned in the text. Consider Whether Your Sources are Current Some disciplines require that you use information that is as current as possible. This is particularly true in disciplines in medicine and the sciences where research conducted becomes obsolete very quickly as new discoveries are made. However, when writing a review in the social sciences, a survey of the history of the literature may be required. In other words, a complete understanding the research problem requires you to deliberately examine how knowledge and perspectives have changed over time. Sort through other current bibliographies or literature reviews in the field to get a sense of what your discipline expects. You can also use this method to explore what is considered by scholars to be a "hot topic" and what is not.

III.  Ways to Organize Your Literature Review

Chronology of Events If your review follows the chronological method, you could write about the materials according to when they were published. This approach should only be followed if a clear path of research building on previous research can be identified and that these trends follow a clear chronological order of development. For example, a literature review that focuses on continuing research about the emergence of German economic power after the fall of the Soviet Union. By Publication Order your sources by publication chronology, then, only if the order demonstrates a more important trend. For instance, you could order a review of literature on environmental studies of brown fields if the progression revealed, for example, a change in the soil collection practices of the researchers who wrote and/or conducted the studies. Thematic [“conceptual categories”] A thematic literature review is the most common approach to summarizing prior research in the social and behavioral sciences. Thematic reviews are organized around a topic or issue, rather than the progression of time, although the progression of time may still be incorporated into a thematic review. For example, a review of the Internet’s impact on American presidential politics could focus on the development of online political satire. While the study focuses on one topic, the Internet’s impact on American presidential politics, it would still be organized chronologically reflecting technological developments in media. The difference in this example between a "chronological" and a "thematic" approach is what is emphasized the most: themes related to the role of the Internet in presidential politics. Note that more authentic thematic reviews tend to break away from chronological order. A review organized in this manner would shift between time periods within each section according to the point being made. Methodological A methodological approach focuses on the methods utilized by the researcher. For the Internet in American presidential politics project, one methodological approach would be to look at cultural differences between the portrayal of American presidents on American, British, and French websites. Or the review might focus on the fundraising impact of the Internet on a particular political party. A methodological scope will influence either the types of documents in the review or the way in which these documents are discussed.

Other Sections of Your Literature Review Once you've decided on the organizational method for your literature review, the sections you need to include in the paper should be easy to figure out because they arise from your organizational strategy. In other words, a chronological review would have subsections for each vital time period; a thematic review would have subtopics based upon factors that relate to the theme or issue. However, sometimes you may need to add additional sections that are necessary for your study, but do not fit in the organizational strategy of the body. What other sections you include in the body is up to you. However, only include what is necessary for the reader to locate your study within the larger scholarship about the research problem.

Here are examples of other sections, usually in the form of a single paragraph, you may need to include depending on the type of review you write:

• Current Situation : Information necessary to understand the current topic or focus of the literature review.
• Sources Used : Describes the methods and resources [e.g., databases] you used to identify the literature you reviewed.
• History : The chronological progression of the field, the research literature, or an idea that is necessary to understand the literature review, if the body of the literature review is not already a chronology.
• Selection Methods : Criteria you used to select (and perhaps exclude) sources in your literature review. For instance, you might explain that your review includes only peer-reviewed [i.e., scholarly] sources.
• Standards : Description of the way in which you present your information.
• Questions for Further Research : What questions about the field has the review sparked? How will you further your research as a result of the review?

IV.  Writing Your Literature Review

Once you've settled on how to organize your literature review, you're ready to write each section. When writing your review, keep in mind these issues.

Use Evidence A literature review section is, in this sense, just like any other academic research paper. Your interpretation of the available sources must be backed up with evidence [citations] that demonstrates that what you are saying is valid. Be Selective Select only the most important points in each source to highlight in the review. The type of information you choose to mention should relate directly to the research problem, whether it is thematic, methodological, or chronological. Related items that provide additional information, but that are not key to understanding the research problem, can be included in a list of further readings . Use Quotes Sparingly Some short quotes are appropriate if you want to emphasize a point, or if what an author stated cannot be easily paraphrased. Sometimes you may need to quote certain terminology that was coined by the author, is not common knowledge, or taken directly from the study. Do not use extensive quotes as a substitute for using your own words in reviewing the literature. Summarize and Synthesize Remember to summarize and synthesize your sources within each thematic paragraph as well as throughout the review. Recapitulate important features of a research study, but then synthesize it by rephrasing the study's significance and relating it to your own work and the work of others. Keep Your Own Voice While the literature review presents others' ideas, your voice [the writer's] should remain front and center. For example, weave references to other sources into what you are writing but maintain your own voice by starting and ending the paragraph with your own ideas and wording. Use Caution When Paraphrasing When paraphrasing a source that is not your own, be sure to represent the author's information or opinions accurately and in your own words. Even when paraphrasing an author’s work, you still must provide a citation to that work.

V.  Common Mistakes to Avoid

These are the most common mistakes made in reviewing social science research literature.

• Sources in your literature review do not clearly relate to the research problem;
• You do not take sufficient time to define and identify the most relevant sources to use in the literature review related to the research problem;
• Relies exclusively on secondary analytical sources rather than including relevant primary research studies or data;
• Uncritically accepts another researcher's findings and interpretations as valid, rather than examining critically all aspects of the research design and analysis;
• Does not describe the search procedures that were used in identifying the literature to review;
• Reports isolated statistical results rather than synthesizing them in chi-squared or meta-analytic methods; and,
• Only includes research that validates assumptions and does not consider contrary findings and alternative interpretations found in the literature.

Cook, Kathleen E. and Elise Murowchick. “Do Literature Review Skills Transfer from One Course to Another?” Psychology Learning and Teaching 13 (March 2014): 3-11; Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper . 2nd ed. Thousand Oaks, CA: Sage, 2005; Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1998; Jesson, Jill. Doing Your Literature Review: Traditional and Systematic Techniques . London: SAGE, 2011; Literature Review Handout. Online Writing Center. Liberty University; Literature Reviews. The Writing Center. University of North Carolina; Onwuegbuzie, Anthony J. and Rebecca Frels. Seven Steps to a Comprehensive Literature Review: A Multimodal and Cultural Approach . Los Angeles, CA: SAGE, 2016; Ridley, Diana. The Literature Review: A Step-by-Step Guide for Students . 2nd ed. Los Angeles, CA: SAGE, 2012; Randolph, Justus J. “A Guide to Writing the Dissertation Literature Review." Practical Assessment, Research, and Evaluation. vol. 14, June 2009; Sutton, Anthea. Systematic Approaches to a Successful Literature Review . Los Angeles, CA: Sage Publications, 2016; Taylor, Dena. The Literature Review: A Few Tips On Conducting It. University College Writing Centre. University of Toronto; Writing a Literature Review. Academic Skills Centre. University of Canberra.

Writing Tip

Break Out of Your Disciplinary Box!

Thinking interdisciplinarily about a research problem can be a rewarding exercise in applying new ideas, theories, or concepts to an old problem. For example, what might cultural anthropologists say about the continuing conflict in the Middle East? In what ways might geographers view the need for better distribution of social service agencies in large cities than how social workers might study the issue? You don’t want to substitute a thorough review of core research literature in your discipline for studies conducted in other fields of study. However, particularly in the social sciences, thinking about research problems from multiple vectors is a key strategy for finding new solutions to a problem or gaining a new perspective. Consult with a librarian about identifying research databases in other disciplines; almost every field of study has at least one comprehensive database devoted to indexing its research literature.

Frodeman, Robert. The Oxford Handbook of Interdisciplinarity . New York: Oxford University Press, 2010.

Another Writing Tip

Don't Just Review for Content!

While conducting a review of the literature, maximize the time you devote to writing this part of your paper by thinking broadly about what you should be looking for and evaluating. Review not just what scholars are saying, but how are they saying it. Some questions to ask:

• How are they organizing their ideas?
• What methods have they used to study the problem?
• What theories have been used to explain, predict, or understand their research problem?
• What sources have they cited to support their conclusions?
• How have they used non-textual elements [e.g., charts, graphs, figures, etc.] to illustrate key points?

When you begin to write your literature review section, you'll be glad you dug deeper into how the research was designed and constructed because it establishes a means for developing more substantial analysis and interpretation of the research problem.

Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1 998.

Yet Another Writing Tip

When Do I Know I Can Stop Looking and Move On?

Here are several strategies you can utilize to assess whether you've thoroughly reviewed the literature:

• Look for repeating patterns in the research findings . If the same thing is being said, just by different people, then this likely demonstrates that the research problem has hit a conceptual dead end. At this point consider: Does your study extend current research?  Does it forge a new path? Or, does is merely add more of the same thing being said?
• Look at sources the authors cite to in their work . If you begin to see the same researchers cited again and again, then this is often an indication that no new ideas have been generated to address the research problem.
• Search Google Scholar to identify who has subsequently cited leading scholars already identified in your literature review [see next sub-tab]. This is called citation tracking and there are a number of sources that can help you identify who has cited whom, particularly scholars from outside of your discipline. Here again, if the same authors are being cited again and again, this may indicate no new literature has been written on the topic.

Onwuegbuzie, Anthony J. and Rebecca Frels. Seven Steps to a Comprehensive Literature Review: A Multimodal and Cultural Approach . Los Angeles, CA: Sage, 2016; Sutton, Anthea. Systematic Approaches to a Successful Literature Review . Los Angeles, CA: Sage Publications, 2016.

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• Last Updated: Aug 27, 2024 1:14 PM
• URL: https://libguides.usc.edu/writingguide

What is Literature Review? Importance, Functions, Process,

• Post last modified: 13 August 2023
• Reading time: 12 mins read
• Post category: Research Methodology

What is Literature Review?

A literature review is a critical and comprehensive analysis of existing research, studies, articles, books, and other relevant sources on a specific topic or subject. It serves as a foundational step in the research process, helping researchers understand the current state of knowledge, identify gaps in the literature, and establish a context for their own study.

Table of Content

• 1 What is Literature Review?
• 2 Importance of a Literature Review
• 3 Functions of a Literature Review
• 4.1 Search the Existing Literature in Your Field of Interest
• 4.2 Review the Literature Obtained
• 4.3 Develop a Theoretical Framework
• 4.4 Write the Literature Review
• 5 How to Write a Literature Review
• 6 Types of Sources for Review

In most research reports or research papers, you will see that literature review is an essential element and it forms the basis for advancing knowledge, facilitates theory development, discovers new research areas and closes old ones. When researchers want to understand the management dilemma, they study various books, articles and all other available sources.

In the research reports, the researchers present a summary of their search, study and evaluation of the literature that is already available related to the research topic. When the researcher presents a summary of their study of present literature in addition to their analysis of how this literature is related to or essential for the current research report; then, this process is known as literature review.

For example, in a research paper titled ‘Attrition Analysis in a Leading Sales Organisation in India’, authored by Mamta Mohapatra (International Management Institute, New Delhi, India), Amisha Gupta (Birlasoft, New Delhi, India) and Nikita Lamba (Genpact, New Delhi, India), literature review is presented as follows:

Organisations and researchers usually conduct literature review in order to establish how their own research fits within the context of existing literature.

Apart from these, some other objectives of carrying out literature review are:

• Develop an understanding of how each source of literature helps in understanding the research problem
• Examine the interrelationships among different variables
• Find out ways to interpret earlier similar researches on the topic under study
• Rectify the conflicts that exist among previously conducted studies
• Get an idea regarding the required sample size
• Get an estimate of how much variance is there in the variables of interest
• Understand the type of relationship that exists among variables
• Determine the research method that can be used in the research

Importance of a Literature Review

There are various reasons for carrying out literature review. Majorly, literature review helps in:

• Assessing the current state and level of research on a given topic
• Identifying experts related to particular research
• Identifying questions that need further research and exploration
• Identifying what methodologies have been used in the related past studies and what methodology should be used in current research
• Justifying a proposed research methodology
• Indicating the originality and relevance of the given research problem
• Demonstrating the preparedness of a researcher to complete the research

Functions of a Literature Review

Some of the major functions of literature review are:

• Establishing a context for the research
• Demonstrating that the researcher has actually read related literature extensively and is aware of most theory and methodology related to the given research topic
• Providing a shape for the research under consideration
• Establishing a connection between what the researcher is proposing and what he has already read
• Demonstrating how the findings of researcher can be integrated with the already existing research findings.
• Revealing the differences or areas of gap between present and earlier research findings
• Improving researcher’s research methodology
• Expanding researcher’s knowledge base
• Ensuring that the researcher is carrying out new research that has not been carried out earlier

Process of a Literature Review

The second step in the research process is to carry out the review of already existing literature. Before engaging in literature review, the researcher must be clear as to what is the area and topic of research. There are four steps involved in the literature review process as shown in Figure:

Search the Existing Literature in Your Field of Interest

In the literature review process, the first step is to find out what research has already been done in the area that the researcher has chosen. This step involves preparing a list or bibliography of existing sources of relevant literature such as books, journals, abstracts of articles on your research topic, citation indices and digital libraries.

Review the Literature Obtained

After the researcher has identified related literature including journals, books, research papers, etc.; the next step is to study, evaluate and analyse the literature critically. This study of literature helps a researcher identify themes and issues related to the research topic.

An evaluation of literature helps in:

• Identifying the different theories and their criticism
• Identifying different methodologies used in different studies including their sample size, data used, measurement methods
• Assessing if the researcher’s theory is confirmed beyond doubt
• Preparing a list of different opinions of different researchers and researcher should also add his/her opinion about the validity of these different opinions

Develop a Theoretical Framework

Since carrying out literature review is a time-consuming activity but the researcher has to do it within a limited time. In order to do so, the researcher usually establishes a boundary and parameters for the research work. Also, the researcher must sort information obtained from all the sources of literature. For a researcher, the theoretical framework acts as a base on which he can further or extend his research. At times, the researchers may modify their research framework after analysing the available literature.

Write the Literature Review

The last step in literature review is to make a summary of all the literature that the researcher has studied and reviewed. Usually, writing a literature review starts with a write-up on the main theme of research followed by the important ideas on which the research would focus. After this, the all the major themes and sub-themes to be discussed are organised and related. This will help the researcher in structuring the literature review. The researcher should also identify and describe the theories and studies that are relevant for the study under consideration. The researcher should then list and describe all the gaps that are present in the current body of knowledge. In addition, the researcher may also explain the recent advances and trends in the given research field. To conclude, the researcher should compare and evaluate his findings on the basis of research assumptions, related research theories, hypotheses, applied research designs, variables selected and potential future work speculated by the researchers. Finally, the researcher must acknowledge, cite and quote all the sources that he/she has used in his research. One specific characteristic of literature review is that the researcher must ensure that he gives due credit to all people who have contributed in the research work.

How to Write a Literature Review

While writing the literature review, the researcher must adopt or adhere to certain strategies as follows:

• Establish a focus around the central theme and ideas of the research
• Describe what a reader can expect from the given research study
• Organise the literature research to include basic elements such as introduction, body and conclusions

Types of Sources for Review

A researcher usually uses secondary data for literature review. Some of the major and widely used sources for literature reviews include articles in professional journals, statistical data from government websites and website material from professional organisations.

Apart from the previously mentioned sources, certain other sources of data can also be used by researchers that provide them first-hand information that is important for the study. These sources include reports, theses, emails, letters, conference proceedings, company reports, autobiographies, official reports, research articles, etc.

Apart from these, the researcher may also refer to other such as review articles, academic journals, books, newspapers, documentaries, encyclopaedias, dictionaries, bibliographies and citation indexes.

Business Ethics

( Click on Topic to Read )

• What is Ethics?
• What is Business Ethics?
• Values, Norms, Beliefs and Standards in Business Ethics
• Indian Ethos in Management
• Ethical Issues in Marketing
• Ethical Issues in HRM
• Ethical Issues in IT
• Ethical Issues in Production and Operations Management
• Ethical Issues in Finance and Accounting
• What is Corporate Governance?
• What is Ownership Concentration?
• What is Ownership Composition?
• Types of Companies in India
• Internal Corporate Governance
• External Corporate Governance
• Corporate Governance in India
• What is Enterprise Risk Management (ERM)?
• What is Assessment of Risk?
• What is Risk Register?
• Risk Management Committee

Corporate social responsibility (CSR)

• Theories of CSR
• Arguments Against CSR
• Business Case for CSR
• Importance of CSR in India
• Drivers of Corporate Social Responsibility
• Developing a CSR Strategy
• Implement CSR Commitments
• CSR Marketplace
• CSR at Workplace
• Environmental CSR
• CSR with Communities and in Supply Chain
• Community Interventions
• CSR Monitoring
• CSR Reporting
• Voluntary Codes in CSR
• What is Corporate Ethics?

Lean Six Sigma

• What is Six Sigma?
• What is Lean Six Sigma?
• Value and Waste in Lean Six Sigma
• Six Sigma Team
• MAIC Six Sigma
• Six Sigma in Supply Chains
• What is Binomial, Poisson, Normal Distribution?
• What is Sigma Level?
• What is DMAIC in Six Sigma?
• What is DMADV in Six Sigma?
• Six Sigma Project Charter
• Project Decomposition in Six Sigma
• Critical to Quality (CTQ) Six Sigma
• Process Mapping Six Sigma
• Flowchart and SIPOC
• Gage Repeatability and Reproducibility
• Statistical Diagram
• Lean Techniques for Optimisation Flow
• Failure Modes and Effects Analysis (FMEA)
• What is Process Audits?
• Six Sigma Implementation at Ford
• IBM Uses Six Sigma to Drive Behaviour Change
• Research Methodology
• What is Research?

What is Hypothesis?

• Sampling Method
• Research Methods
• Data Collection in Research
• Methods of Collecting Data

Application of Business Research

• Levels of Measurement
• What is Sampling?
• Hypothesis Testing
• Research Report
• What is Management?
• Planning in Management
• Decision Making in Management
• What is Controlling?
• What is Coordination?
• What is Staffing?
• Organization Structure
• What is Departmentation?
• Span of Control
• What is Authority?
• Centralization vs Decentralization
• Organizing in Management
• Schools of Management Thought
• Classical Management Approach
• Is Management an Art or Science?
• Who is a Manager?

Operations Research

• What is Operations Research?
• Operation Research Models
• Linear Programming
• Linear Programming Graphic Solution
• Linear Programming Simplex Method
• Linear Programming Artificial Variable Technique
• Duality in Linear Programming
• Transportation Problem Initial Basic Feasible Solution
• Transportation Problem Finding Optimal Solution
• Project Network Analysis with Critical Path Method
• Project Network Analysis Methods
• Project Evaluation and Review Technique (PERT)
• Simulation in Operation Research
• Replacement Models in Operation Research

Operation Management

• What is Strategy?
• What is Operations Strategy?
• Operations Competitive Dimensions
• Operations Strategy Formulation Process
• What is Strategic Fit?
• Strategic Design Process
• Focused Operations Strategy
• Corporate Level Strategy
• Expansion Strategies
• Stability Strategies
• Retrenchment Strategies
• Competitive Advantage
• Strategic Choice and Strategic Alternatives
• What is Production Process?
• What is Process Technology?
• What is Process Improvement?
• Strategic Capacity Management
• Production and Logistics Strategy
• Taxonomy of Supply Chain Strategies
• Factors Considered in Supply Chain Planning
• Operational and Strategic Issues in Global Logistics
• Logistics Outsourcing Strategy
• What is Supply Chain Mapping?
• Supply Chain Process Restructuring
• Points of Differentiation
• Re-engineering Improvement in SCM
• What is Supply Chain Drivers?
• Supply Chain Operations Reference (SCOR) Model
• Customer Service and Cost Trade Off
• Internal and External Performance Measures
• Linking Supply Chain and Business Performance
• Netflix’s Niche Focused Strategy
• Disney and Pixar Merger
• Process Planning at Mcdonald’s

Service Operations Management

• What is Service?
• What is Service Operations Management?
• What is Service Design?
• Service Design Process
• Service Delivery
• What is Service Quality?
• Gap Model of Service Quality
• Juran Trilogy
• Service Performance Measurement
• Service Decoupling
• IT Service Operation
• Service Operations Management in Different Sector

Procurement Management

• What is Procurement Management?
• Procurement Negotiation
• Types of Requisition
• RFX in Procurement
• What is Purchasing Cycle?
• Vendor Managed Inventory
• Internal Conflict During Purchasing Operation
• Spend Analysis in Procurement
• Sourcing in Procurement
• Supplier Evaluation and Selection in Procurement
• Blacklisting of Suppliers in Procurement
• Total Cost of Ownership in Procurement
• Incoterms in Procurement
• Documents Used in International Procurement
• Transportation and Logistics Strategy
• What is Capital Equipment?
• Procurement Process of Capital Equipment
• Acquisition of Technology in Procurement
• What is E-Procurement?
• E-marketplace and Online Catalogues
• Fixed Price and Cost Reimbursement Contracts
• Contract Cancellation in Procurement
• Ethics in Procurement
• Legal Aspects of Procurement
• Global Sourcing in Procurement
• Intermediaries and Countertrade in Procurement

Strategic Management

• What is Strategic Management?
• What is Value Chain Analysis?
• Mission Statement
• Business Level Strategy
• What is SWOT Analysis?
• What is Competitive Advantage?
• What is Vision?
• What is Ansoff Matrix?
• Prahalad and Gary Hammel
• Strategic Management In Global Environment
• Competitor Analysis Framework
• Competitive Rivalry Analysis
• Competitive Dynamics
• What is Competitive Rivalry?
• Five Competitive Forces That Shape Strategy
• What is PESTLE Analysis?
• Fragmentation and Consolidation Of Industries
• What is Technology Life Cycle?
• What is Diversification Strategy?
• What is Corporate Restructuring Strategy?
• Resources and Capabilities of Organization
• Role of Leaders In Functional-Level Strategic Management
• Functional Structure In Functional Level Strategy Formulation
• Information And Control System
• What is Strategy Gap Analysis?
• Issues In Strategy Implementation
• Matrix Organizational Structure
• What is Strategic Management Process?

Supply Chain

• What is Supply Chain Management?
• Supply Chain Planning and Measuring Strategy Performance
• What is Warehousing?
• What is Packaging?
• What is Inventory Management?
• What is Material Handling?
• What is Order Picking?
• Receiving and Dispatch, Processes
• What is Warehouse Design?
• What is Warehousing Costs?

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What is a Literature Review? How to Write It (with Examples)

A literature review is a critical analysis and synthesis of existing research on a particular topic. It provides an overview of the current state of knowledge, identifies gaps, and highlights key findings in the literature. 1 The purpose of a literature review is to situate your own research within the context of existing scholarship, demonstrating your understanding of the topic and showing how your work contributes to the ongoing conversation in the field. Learning how to write a literature review is a critical tool for successful research. Your ability to summarize and synthesize prior research pertaining to a certain topic demonstrates your grasp on the topic of study, and assists in the learning process. 

Table of Contents

• What is the purpose of literature review? 
• a. Habitat Loss and Species Extinction: 
• b. Range Shifts and Phenological Changes: 
• c. Ocean Acidification and Coral Reefs: 
• d. Adaptive Strategies and Conservation Efforts: 

How to write a good literature review 

• Choose a Topic and Define the Research Question: 
• Decide on the Scope of Your Review: 
• Select Databases for Searches: 
• Conduct Searches and Keep Track: 
• Review the Literature: 
• Organize and Write Your Literature Review: 
• How to write a literature review faster with Paperpal? 
• Frequently asked questions 

What is a literature review?

A well-conducted literature review demonstrates the researcher’s familiarity with the existing literature, establishes the context for their own research, and contributes to scholarly conversations on the topic. One of the purposes of a literature review is also to help researchers avoid duplicating previous work and ensure that their research is informed by and builds upon the existing body of knowledge.

What is the purpose of literature review?

A literature review serves several important purposes within academic and research contexts. Here are some key objectives and functions of a literature review: 2  

1. Contextualizing the Research Problem: The literature review provides a background and context for the research problem under investigation. It helps to situate the study within the existing body of knowledge. 

2. Identifying Gaps in Knowledge: By identifying gaps, contradictions, or areas requiring further research, the researcher can shape the research question and justify the significance of the study. This is crucial for ensuring that the new research contributes something novel to the field. 

Find academic papers related to your research topic faster. Try Research on Paperpal  

3. Understanding Theoretical and Conceptual Frameworks: Literature reviews help researchers gain an understanding of the theoretical and conceptual frameworks used in previous studies. This aids in the development of a theoretical framework for the current research. 

4. Providing Methodological Insights: Another purpose of literature reviews is that it allows researchers to learn about the methodologies employed in previous studies. This can help in choosing appropriate research methods for the current study and avoiding pitfalls that others may have encountered. 

5. Establishing Credibility: A well-conducted literature review demonstrates the researcher’s familiarity with existing scholarship, establishing their credibility and expertise in the field. It also helps in building a solid foundation for the new research. 

6. Informing Hypotheses or Research Questions: The literature review guides the formulation of hypotheses or research questions by highlighting relevant findings and areas of uncertainty in existing literature. 

Literature review example

Let’s delve deeper with a literature review example: Let’s say your literature review is about the impact of climate change on biodiversity. You might format your literature review into sections such as the effects of climate change on habitat loss and species extinction, phenological changes, and marine biodiversity. Each section would then summarize and analyze relevant studies in those areas, highlighting key findings and identifying gaps in the research. The review would conclude by emphasizing the need for further research on specific aspects of the relationship between climate change and biodiversity. The following literature review template provides a glimpse into the recommended literature review structure and content, demonstrating how research findings are organized around specific themes within a broader topic. 

Literature Review on Climate Change Impacts on Biodiversity:

Climate change is a global phenomenon with far-reaching consequences, including significant impacts on biodiversity. This literature review synthesizes key findings from various studies: 

a. Habitat Loss and Species Extinction:

Climate change-induced alterations in temperature and precipitation patterns contribute to habitat loss, affecting numerous species (Thomas et al., 2004). The review discusses how these changes increase the risk of extinction, particularly for species with specific habitat requirements. 

b. Range Shifts and Phenological Changes:

Observations of range shifts and changes in the timing of biological events (phenology) are documented in response to changing climatic conditions (Parmesan & Yohe, 2003). These shifts affect ecosystems and may lead to mismatches between species and their resources. 

c. Ocean Acidification and Coral Reefs:

The review explores the impact of climate change on marine biodiversity, emphasizing ocean acidification’s threat to coral reefs (Hoegh-Guldberg et al., 2007). Changes in pH levels negatively affect coral calcification, disrupting the delicate balance of marine ecosystems. 

d. Adaptive Strategies and Conservation Efforts:

Recognizing the urgency of the situation, the literature review discusses various adaptive strategies adopted by species and conservation efforts aimed at mitigating the impacts of climate change on biodiversity (Hannah et al., 2007). It emphasizes the importance of interdisciplinary approaches for effective conservation planning. 

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Writing a literature review involves summarizing and synthesizing existing research on a particular topic. A good literature review format should include the following elements. 

Introduction: The introduction sets the stage for your literature review, providing context and introducing the main focus of your review. 

• Opening Statement: Begin with a general statement about the broader topic and its significance in the field. 
• Scope and Purpose: Clearly define the scope of your literature review. Explain the specific research question or objective you aim to address. 
• Organizational Framework: Briefly outline the structure of your literature review, indicating how you will categorize and discuss the existing research. 
• Significance of the Study: Highlight why your literature review is important and how it contributes to the understanding of the chosen topic. 
• Thesis Statement: Conclude the introduction with a concise thesis statement that outlines the main argument or perspective you will develop in the body of the literature review. 

Body: The body of the literature review is where you provide a comprehensive analysis of existing literature, grouping studies based on themes, methodologies, or other relevant criteria. 

• Organize by Theme or Concept: Group studies that share common themes, concepts, or methodologies. Discuss each theme or concept in detail, summarizing key findings and identifying gaps or areas of disagreement. 
• Critical Analysis: Evaluate the strengths and weaknesses of each study. Discuss the methodologies used, the quality of evidence, and the overall contribution of each work to the understanding of the topic. 
• Synthesis of Findings: Synthesize the information from different studies to highlight trends, patterns, or areas of consensus in the literature. 
• Identification of Gaps: Discuss any gaps or limitations in the existing research and explain how your review contributes to filling these gaps. 
• Transition between Sections: Provide smooth transitions between different themes or concepts to maintain the flow of your literature review. 

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Conclusion: The conclusion of your literature review should summarize the main findings, highlight the contributions of the review, and suggest avenues for future research. 

• Summary of Key Findings: Recap the main findings from the literature and restate how they contribute to your research question or objective. 
• Contributions to the Field: Discuss the overall contribution of your literature review to the existing knowledge in the field. 
• Implications and Applications: Explore the practical implications of the findings and suggest how they might impact future research or practice. 
• Recommendations for Future Research: Identify areas that require further investigation and propose potential directions for future research in the field. 
• Final Thoughts: Conclude with a final reflection on the importance of your literature review and its relevance to the broader academic community. 

Conducting a literature review

Conducting a literature review is an essential step in research that involves reviewing and analyzing existing literature on a specific topic. It’s important to know how to do a literature review effectively, so here are the steps to follow: 1  

Choose a Topic and Define the Research Question:

• Select a topic that is relevant to your field of study. 
• Clearly define your research question or objective. Determine what specific aspect of the topic do you want to explore? 

Decide on the Scope of Your Review:

• Determine the timeframe for your literature review. Are you focusing on recent developments, or do you want a historical overview? 
• Consider the geographical scope. Is your review global, or are you focusing on a specific region? 
• Define the inclusion and exclusion criteria. What types of sources will you include? Are there specific types of studies or publications you will exclude? 

Select Databases for Searches:

• Identify relevant databases for your field. Examples include PubMed, IEEE Xplore, Scopus, Web of Science, and Google Scholar. 
• Consider searching in library catalogs, institutional repositories, and specialized databases related to your topic. 

Conduct Searches and Keep Track:

• Develop a systematic search strategy using keywords, Boolean operators (AND, OR, NOT), and other search techniques. 
• Record and document your search strategy for transparency and replicability. 
• Keep track of the articles, including publication details, abstracts, and links. Use citation management tools like EndNote, Zotero, or Mendeley to organize your references. 

Review the Literature:

• Evaluate the relevance and quality of each source. Consider the methodology, sample size, and results of studies. 
• Organize the literature by themes or key concepts. Identify patterns, trends, and gaps in the existing research. 
• Summarize key findings and arguments from each source. Compare and contrast different perspectives. 
• Identify areas where there is a consensus in the literature and where there are conflicting opinions. 
• Provide critical analysis and synthesis of the literature. What are the strengths and weaknesses of existing research? 

Organize and Write Your Literature Review:

• Literature review outline should be based on themes, chronological order, or methodological approaches. 
• Write a clear and coherent narrative that synthesizes the information gathered. 
• Use proper citations for each source and ensure consistency in your citation style (APA, MLA, Chicago, etc.). 
• Conclude your literature review by summarizing key findings, identifying gaps, and suggesting areas for future research. 

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• Cite with Confidence: Paperpal makes it easy to incorporate relevant citations and references into your writing, ensuring your arguments are well-supported by credible sources. This translates to a polished, well-researched literature review. 

The literature review sample and detailed advice on writing and conducting a review will help you produce a well-structured report. But remember that a good literature review is an ongoing process, and it may be necessary to revisit and update it as your research progresses. By combining effortless research with an easy citation process, Paperpal Research streamlines the literature review process and empowers you to write faster and with more confidence. Try Paperpal Research now and see for yourself.  

Frequently asked questions

A literature review is a critical and comprehensive analysis of existing literature (published and unpublished works) on a specific topic or research question and provides a synthesis of the current state of knowledge in a particular field. A well-conducted literature review is crucial for researchers to build upon existing knowledge, avoid duplication of efforts, and contribute to the advancement of their field. It also helps researchers situate their work within a broader context and facilitates the development of a sound theoretical and conceptual framework for their studies.

Literature review is a crucial component of research writing, providing a solid background for a research paper’s investigation. The aim is to keep professionals up to date by providing an understanding of ongoing developments within a specific field, including research methods, and experimental techniques used in that field, and present that knowledge in the form of a written report. Also, the depth and breadth of the literature review emphasizes the credibility of the scholar in his or her field.  

Before writing a literature review, it’s essential to undertake several preparatory steps to ensure that your review is well-researched, organized, and focused. This includes choosing a topic of general interest to you and doing exploratory research on that topic, writing an annotated bibliography, and noting major points, especially those that relate to the position you have taken on the topic. 

Literature reviews and academic research papers are essential components of scholarly work but serve different purposes within the academic realm. 3 A literature review aims to provide a foundation for understanding the current state of research on a particular topic, identify gaps or controversies, and lay the groundwork for future research. Therefore, it draws heavily from existing academic sources, including books, journal articles, and other scholarly publications. In contrast, an academic research paper aims to present new knowledge, contribute to the academic discourse, and advance the understanding of a specific research question. Therefore, it involves a mix of existing literature (in the introduction and literature review sections) and original data or findings obtained through research methods. 

Literature reviews are essential components of academic and research papers, and various strategies can be employed to conduct them effectively. If you want to know how to write a literature review for a research paper, here are four common approaches that are often used by researchers.  Chronological Review: This strategy involves organizing the literature based on the chronological order of publication. It helps to trace the development of a topic over time, showing how ideas, theories, and research have evolved.  Thematic Review: Thematic reviews focus on identifying and analyzing themes or topics that cut across different studies. Instead of organizing the literature chronologically, it is grouped by key themes or concepts, allowing for a comprehensive exploration of various aspects of the topic.  Methodological Review: This strategy involves organizing the literature based on the research methods employed in different studies. It helps to highlight the strengths and weaknesses of various methodologies and allows the reader to evaluate the reliability and validity of the research findings.  Theoretical Review: A theoretical review examines the literature based on the theoretical frameworks used in different studies. This approach helps to identify the key theories that have been applied to the topic and assess their contributions to the understanding of the subject.  It’s important to note that these strategies are not mutually exclusive, and a literature review may combine elements of more than one approach. The choice of strategy depends on the research question, the nature of the literature available, and the goals of the review. Additionally, other strategies, such as integrative reviews or systematic reviews, may be employed depending on the specific requirements of the research.

The literature review format can vary depending on the specific publication guidelines. However, there are some common elements and structures that are often followed. Here is a general guideline for the format of a literature review:  Introduction:   Provide an overview of the topic.  Define the scope and purpose of the literature review.  State the research question or objective.  Body:   Organize the literature by themes, concepts, or chronology.  Critically analyze and evaluate each source.  Discuss the strengths and weaknesses of the studies.  Highlight any methodological limitations or biases.  Identify patterns, connections, or contradictions in the existing research.  Conclusion:   Summarize the key points discussed in the literature review.  Highlight the research gap.  Address the research question or objective stated in the introduction.  Highlight the contributions of the review and suggest directions for future research.

Both annotated bibliographies and literature reviews involve the examination of scholarly sources. While annotated bibliographies focus on individual sources with brief annotations, literature reviews provide a more in-depth, integrated, and comprehensive analysis of existing literature on a specific topic. The key differences are as follows: 

References 

• Denney, A. S., & Tewksbury, R. (2013). How to write a literature review.  Journal of criminal justice education ,  24 (2), 218-234. 
• Pan, M. L. (2016).  Preparing literature reviews: Qualitative and quantitative approaches . Taylor & Francis. 
• Cantero, C. (2019). How to write a literature review.  San José State University Writing Center . 

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Ten Simple Rules for Writing a Literature Review

Marco pautasso.

1 Centre for Functional and Evolutionary Ecology (CEFE), CNRS, Montpellier, France

2 Centre for Biodiversity Synthesis and Analysis (CESAB), FRB, Aix-en-Provence, France

Literature reviews are in great demand in most scientific fields. Their need stems from the ever-increasing output of scientific publications [1] . For example, compared to 1991, in 2008 three, eight, and forty times more papers were indexed in Web of Science on malaria, obesity, and biodiversity, respectively [2] . Given such mountains of papers, scientists cannot be expected to examine in detail every single new paper relevant to their interests [3] . Thus, it is both advantageous and necessary to rely on regular summaries of the recent literature. Although recognition for scientists mainly comes from primary research, timely literature reviews can lead to new synthetic insights and are often widely read [4] . For such summaries to be useful, however, they need to be compiled in a professional way [5] .

When starting from scratch, reviewing the literature can require a titanic amount of work. That is why researchers who have spent their career working on a certain research issue are in a perfect position to review that literature. Some graduate schools are now offering courses in reviewing the literature, given that most research students start their project by producing an overview of what has already been done on their research issue [6] . However, it is likely that most scientists have not thought in detail about how to approach and carry out a literature review.

Reviewing the literature requires the ability to juggle multiple tasks, from finding and evaluating relevant material to synthesising information from various sources, from critical thinking to paraphrasing, evaluating, and citation skills [7] . In this contribution, I share ten simple rules I learned working on about 25 literature reviews as a PhD and postdoctoral student. Ideas and insights also come from discussions with coauthors and colleagues, as well as feedback from reviewers and editors.

Rule 1: Define a Topic and Audience

How to choose which topic to review? There are so many issues in contemporary science that you could spend a lifetime of attending conferences and reading the literature just pondering what to review. On the one hand, if you take several years to choose, several other people may have had the same idea in the meantime. On the other hand, only a well-considered topic is likely to lead to a brilliant literature review [8] . The topic must at least be:

• interesting to you (ideally, you should have come across a series of recent papers related to your line of work that call for a critical summary),
• an important aspect of the field (so that many readers will be interested in the review and there will be enough material to write it), and
• a well-defined issue (otherwise you could potentially include thousands of publications, which would make the review unhelpful).

Ideas for potential reviews may come from papers providing lists of key research questions to be answered [9] , but also from serendipitous moments during desultory reading and discussions. In addition to choosing your topic, you should also select a target audience. In many cases, the topic (e.g., web services in computational biology) will automatically define an audience (e.g., computational biologists), but that same topic may also be of interest to neighbouring fields (e.g., computer science, biology, etc.).

Rule 2: Search and Re-search the Literature

After having chosen your topic and audience, start by checking the literature and downloading relevant papers. Five pieces of advice here:

• keep track of the search items you use (so that your search can be replicated [10] ),
• keep a list of papers whose pdfs you cannot access immediately (so as to retrieve them later with alternative strategies),
• use a paper management system (e.g., Mendeley, Papers, Qiqqa, Sente),
• define early in the process some criteria for exclusion of irrelevant papers (these criteria can then be described in the review to help define its scope), and
• do not just look for research papers in the area you wish to review, but also seek previous reviews.

The chances are high that someone will already have published a literature review ( Figure 1 ), if not exactly on the issue you are planning to tackle, at least on a related topic. If there are already a few or several reviews of the literature on your issue, my advice is not to give up, but to carry on with your own literature review,

The bottom-right situation (many literature reviews but few research papers) is not just a theoretical situation; it applies, for example, to the study of the impacts of climate change on plant diseases, where there appear to be more literature reviews than research studies [33] .

• discussing in your review the approaches, limitations, and conclusions of past reviews,
• trying to find a new angle that has not been covered adequately in the previous reviews, and
• incorporating new material that has inevitably accumulated since their appearance.

When searching the literature for pertinent papers and reviews, the usual rules apply:

• be thorough,
• use different keywords and database sources (e.g., DBLP, Google Scholar, ISI Proceedings, JSTOR Search, Medline, Scopus, Web of Science), and
• look at who has cited past relevant papers and book chapters.

Rule 3: Take Notes While Reading

If you read the papers first, and only afterwards start writing the review, you will need a very good memory to remember who wrote what, and what your impressions and associations were while reading each single paper. My advice is, while reading, to start writing down interesting pieces of information, insights about how to organize the review, and thoughts on what to write. This way, by the time you have read the literature you selected, you will already have a rough draft of the review.

Of course, this draft will still need much rewriting, restructuring, and rethinking to obtain a text with a coherent argument [11] , but you will have avoided the danger posed by staring at a blank document. Be careful when taking notes to use quotation marks if you are provisionally copying verbatim from the literature. It is advisable then to reformulate such quotes with your own words in the final draft. It is important to be careful in noting the references already at this stage, so as to avoid misattributions. Using referencing software from the very beginning of your endeavour will save you time.

Rule 4: Choose the Type of Review You Wish to Write

After having taken notes while reading the literature, you will have a rough idea of the amount of material available for the review. This is probably a good time to decide whether to go for a mini- or a full review. Some journals are now favouring the publication of rather short reviews focusing on the last few years, with a limit on the number of words and citations. A mini-review is not necessarily a minor review: it may well attract more attention from busy readers, although it will inevitably simplify some issues and leave out some relevant material due to space limitations. A full review will have the advantage of more freedom to cover in detail the complexities of a particular scientific development, but may then be left in the pile of the very important papers “to be read” by readers with little time to spare for major monographs.

There is probably a continuum between mini- and full reviews. The same point applies to the dichotomy of descriptive vs. integrative reviews. While descriptive reviews focus on the methodology, findings, and interpretation of each reviewed study, integrative reviews attempt to find common ideas and concepts from the reviewed material [12] . A similar distinction exists between narrative and systematic reviews: while narrative reviews are qualitative, systematic reviews attempt to test a hypothesis based on the published evidence, which is gathered using a predefined protocol to reduce bias [13] , [14] . When systematic reviews analyse quantitative results in a quantitative way, they become meta-analyses. The choice between different review types will have to be made on a case-by-case basis, depending not just on the nature of the material found and the preferences of the target journal(s), but also on the time available to write the review and the number of coauthors [15] .

Rule 5: Keep the Review Focused, but Make It of Broad Interest

Whether your plan is to write a mini- or a full review, it is good advice to keep it focused 16 , 17 . Including material just for the sake of it can easily lead to reviews that are trying to do too many things at once. The need to keep a review focused can be problematic for interdisciplinary reviews, where the aim is to bridge the gap between fields [18] . If you are writing a review on, for example, how epidemiological approaches are used in modelling the spread of ideas, you may be inclined to include material from both parent fields, epidemiology and the study of cultural diffusion. This may be necessary to some extent, but in this case a focused review would only deal in detail with those studies at the interface between epidemiology and the spread of ideas.

While focus is an important feature of a successful review, this requirement has to be balanced with the need to make the review relevant to a broad audience. This square may be circled by discussing the wider implications of the reviewed topic for other disciplines.

Rule 6: Be Critical and Consistent

Reviewing the literature is not stamp collecting. A good review does not just summarize the literature, but discusses it critically, identifies methodological problems, and points out research gaps [19] . After having read a review of the literature, a reader should have a rough idea of:

• the major achievements in the reviewed field,
• the main areas of debate, and
• the outstanding research questions.

It is challenging to achieve a successful review on all these fronts. A solution can be to involve a set of complementary coauthors: some people are excellent at mapping what has been achieved, some others are very good at identifying dark clouds on the horizon, and some have instead a knack at predicting where solutions are going to come from. If your journal club has exactly this sort of team, then you should definitely write a review of the literature! In addition to critical thinking, a literature review needs consistency, for example in the choice of passive vs. active voice and present vs. past tense.

Rule 7: Find a Logical Structure

Like a well-baked cake, a good review has a number of telling features: it is worth the reader's time, timely, systematic, well written, focused, and critical. It also needs a good structure. With reviews, the usual subdivision of research papers into introduction, methods, results, and discussion does not work or is rarely used. However, a general introduction of the context and, toward the end, a recapitulation of the main points covered and take-home messages make sense also in the case of reviews. For systematic reviews, there is a trend towards including information about how the literature was searched (database, keywords, time limits) [20] .

How can you organize the flow of the main body of the review so that the reader will be drawn into and guided through it? It is generally helpful to draw a conceptual scheme of the review, e.g., with mind-mapping techniques. Such diagrams can help recognize a logical way to order and link the various sections of a review [21] . This is the case not just at the writing stage, but also for readers if the diagram is included in the review as a figure. A careful selection of diagrams and figures relevant to the reviewed topic can be very helpful to structure the text too [22] .

Rule 8: Make Use of Feedback

Reviews of the literature are normally peer-reviewed in the same way as research papers, and rightly so [23] . As a rule, incorporating feedback from reviewers greatly helps improve a review draft. Having read the review with a fresh mind, reviewers may spot inaccuracies, inconsistencies, and ambiguities that had not been noticed by the writers due to rereading the typescript too many times. It is however advisable to reread the draft one more time before submission, as a last-minute correction of typos, leaps, and muddled sentences may enable the reviewers to focus on providing advice on the content rather than the form.

Feedback is vital to writing a good review, and should be sought from a variety of colleagues, so as to obtain a diversity of views on the draft. This may lead in some cases to conflicting views on the merits of the paper, and on how to improve it, but such a situation is better than the absence of feedback. A diversity of feedback perspectives on a literature review can help identify where the consensus view stands in the landscape of the current scientific understanding of an issue [24] .

Rule 9: Include Your Own Relevant Research, but Be Objective

In many cases, reviewers of the literature will have published studies relevant to the review they are writing. This could create a conflict of interest: how can reviewers report objectively on their own work [25] ? Some scientists may be overly enthusiastic about what they have published, and thus risk giving too much importance to their own findings in the review. However, bias could also occur in the other direction: some scientists may be unduly dismissive of their own achievements, so that they will tend to downplay their contribution (if any) to a field when reviewing it.

In general, a review of the literature should neither be a public relations brochure nor an exercise in competitive self-denial. If a reviewer is up to the job of producing a well-organized and methodical review, which flows well and provides a service to the readership, then it should be possible to be objective in reviewing one's own relevant findings. In reviews written by multiple authors, this may be achieved by assigning the review of the results of a coauthor to different coauthors.

Rule 10: Be Up-to-Date, but Do Not Forget Older Studies

Given the progressive acceleration in the publication of scientific papers, today's reviews of the literature need awareness not just of the overall direction and achievements of a field of inquiry, but also of the latest studies, so as not to become out-of-date before they have been published. Ideally, a literature review should not identify as a major research gap an issue that has just been addressed in a series of papers in press (the same applies, of course, to older, overlooked studies (“sleeping beauties” [26] )). This implies that literature reviewers would do well to keep an eye on electronic lists of papers in press, given that it can take months before these appear in scientific databases. Some reviews declare that they have scanned the literature up to a certain point in time, but given that peer review can be a rather lengthy process, a full search for newly appeared literature at the revision stage may be worthwhile. Assessing the contribution of papers that have just appeared is particularly challenging, because there is little perspective with which to gauge their significance and impact on further research and society.

Inevitably, new papers on the reviewed topic (including independently written literature reviews) will appear from all quarters after the review has been published, so that there may soon be the need for an updated review. But this is the nature of science [27] – [32] . I wish everybody good luck with writing a review of the literature.

Acknowledgments

Many thanks to M. Barbosa, K. Dehnen-Schmutz, T. Döring, D. Fontaneto, M. Garbelotto, O. Holdenrieder, M. Jeger, D. Lonsdale, A. MacLeod, P. Mills, M. Moslonka-Lefebvre, G. Stancanelli, P. Weisberg, and X. Xu for insights and discussions, and to P. Bourne, T. Matoni, and D. Smith for helpful comments on a previous draft.

Funding Statement

This work was funded by the French Foundation for Research on Biodiversity (FRB) through its Centre for Synthesis and Analysis of Biodiversity data (CESAB), as part of the NETSEED research project. The funders had no role in the preparation of the manuscript.

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• literature review

Functions of a literature review

A literature review basically has three functions:

• to convey to the reader what knowledge and ideas have been established on a topic, and what their strengths and weaknesses are;
• in doing so, you clearly pass the message to the reader that you are familiar with these theories & ideas. Consequently, you are somewhat more of an expert writer, or so the reader may think.
• present your ideas on the matter & your theorie(s).

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A systematic review of the key predictors of progression and mortality of rheumatoid arthritis-associated interstitial lung disease.

1. Introduction

2. materials and methods, 2.1. eligibility, 2.2. search strategy, 2.3. data extraction, 3.1. selection of studies, 3.2. demographic features of eligible studies, 3.3. risk factors of lung function decline, 3.4. prognostic factors for all-cause mortality of ra-ild, 3.5. additional analysis, 4. discussion, 5. conclusions, author contributions, institutional review board statement, informed consent statement, data availability statement, conflicts of interest.

• Aletaha, D.; Smolen, J.S. Diagnosis and Management of Rheumatoid Arthritis: A Review. JAMA 2018 , 320 , 1360–1372. [ Google Scholar ] [ CrossRef ]
• Almutairi, K.; Nossent, J.; Preen, D.; Keen, H.; Inderjeeth, C. The global prevalence of rheumatoid arthritis: A meta-analysis based on a systematic review. Rheumatol. Int. 2021 , 41 , 863–877. [ Google Scholar ] [ CrossRef ]
• Kadura, S.; Raghu, G. Rheumatoid arthritis-interstitial lung disease: Manifestations and current concepts in pathogenesis and management. Eur. Respir. Rev. 2021 , 30 , 210011. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Huang, S.; Kronzer, V.L.; Dellaripa, P.F.; Deane, K.D.; Bolster, M.B.; Nagaraja, V.; Khanna, D.; Doyle, T.J.; Sparks, J.A. Rheumatoid Arthritis–Associated Interstitial Lung Disease: Current Update on Prevalence, Risk Factors, and Pharmacologic Treatment. Curr. Treat. Options Rheumatol. 2020 , 6 , 337–353. [ Google Scholar ] [ CrossRef ]
• Fazeli, M.S.; Khaychuk, V.; Wittstock, K.; Han, X.; Crocket, G.; Lin, M.; Ferri, L. Rheumatoid Arthritis-Associated Interstitial Lung Disease: Epidemiology, Risk/Prognostic Factors, and Treatment Landscape. Clin. Exp. Rheumatol. 2021 , 39 , 1108–1118. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Wang, H.F.; Wang, Y.Y.; Li, Z.Y.; He, P.J.; Liu, S.; Li, Q.S. The prevalence and risk factors of rheumatoid arthritis-associated interstitial lung disease: A systematic review and meta-analysis. Ann. Med. 2024 , 56 , 2332406. [ Google Scholar ] [ CrossRef ]
• Albrecht, K.; Strangfeld, A.; Marschall, U.; Callhoff, J. Interstitial lung disease in rheumatoid arthritis: Incidence, prevalence and related drug prescriptions between 2007 and 2020. RMD Open 2023 , 9 , e002777. [ Google Scholar ] [ CrossRef ]
• Laria, A.; Lurati, A.M.; Zizzo, G.; Zaccara, E.; Mazzocchi, D.; Re, K.A.; Marrazza, M.; Faggioli, P.; Mazzone, A. Interstitial Lung Disease in Rheumatoid Arthritis: A Practical Review. Front. Med. 2022 , 9 , 837133. [ Google Scholar ] [ CrossRef ]
• Lee, H.; Lee, S.I.; Kim, H.O. Recent Advances in Basic and Clinical Aspects of Rheumatoid Arthritis-associated Interstitial Lung Diseases. J. Rheum. Dis. 2022 , 29 , 61–70. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Yang, Y.; Zhang, Z.; Zhang, X.; Zhang, X.; Zhi, K.; Zhao, X.; Zhao, J.; Cao, W. Rheumatoid arthritis-associated interstitial lung disease hotspots and future directions: A Web-of-Science based scientometric and visualization study. Immun. Inflamm. Dis. 2023 , 11 , e944. [ Google Scholar ] [ CrossRef ]
• Fischer, A.; Du Bois, R. Interstitial lung disease in connective tissue disorders. Lancet 2012 , 380 , 689–698. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Kolb, M.; Vašáková, M. The natural history of progressive fibrosing interstitial lung diseases. Respir. Res. 2019 , 20 , 57. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Duarte, C.; Ferreira, R.J.O.; Santos, E.J.F.; Da Silva, J.A.P. Treating-to-target in rheumatology: Theory and practice. Best. Pract. Res. Clin. Rheumatol. 2022 , 36 , 101735. [ Google Scholar ] [ CrossRef ]
• Challa, D.N.V.; Crowson, C.S.; Davis, J.M. The Patient Global Assessment of Disease Activity in Rheumatoid Arthritis: Identification of Underlying Latent Factors. Rheumatol. Ther. 2017 , 4 , 201–208. [ Google Scholar ] [ CrossRef ]
• du Bois, R.M.; Weycker, D.; Albera, C.; Bradford, W.Z.; Costabel, U.; Kartashov, A.; King, T.E., Jr. Ascertainment of Individual Risk of Mortality for Patients with Idiopathic Pulmonary Fibrosis. Am. J. Respir. Crit. Care Med. 2011 , 184 , 459–466. [ Google Scholar ] [ CrossRef ]
• Kelly, C.A.; Saravanan, V.; Nisar, M.; Arthanari, S.; Woodhead, F.A.; Price-Forbes, A.N.; Dawson, J.; Sathi, N.; Ahmad, Y.; Koduri, G.; et al. Rheumatoid arthritis-related interstitial lung disease: Associations, prognostic factors and physiological and radiological characteristics—A large multicentre UK study. Rheumatology 2014 , 53 , 1676–1682. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Juge, P.A.; Crestani, B.; Dieudé, P. Recent advances in rheumatoid arthritis-associated interstitial lung disease. Curr. Opin. Pulm. Med. 2020 , 26 , 477–486. [ Google Scholar ] [ CrossRef ]
• Akiyama, M.; Kaneko, Y. Pathogenesis, clinical features, and treatment strategy for rheumatoid arthritis-associated interstitial lung disease. Autoimmun. Rev. 2022 , 21 , 103056. [ Google Scholar ] [ CrossRef ]
• Dai, Y.; Wang, W.; Yu, Y.; Hu, S. Rheumatoid arthritis–associated interstitial lung disease: An overview of epidemiology, pathogenesis and management. Clin. Rheumatol. 2021 , 40 , 1211–1220. [ Google Scholar ] [ CrossRef ]
• Al-Baldawi, S.; Zúñiga Salazar, G.; Zúñiga, D.; Balasubramanian, S.; Mehmood, K.T. Interstitial Lung Disease in Rheumatoid Arthritis: A Review. 5 February 2024. Available online: https://www.cureus.com/articles/220746-interstitial-lung-disease-in-rheumatoid-arthritis-a-review (accessed on 8 August 2024).
• Xie, M.; Zhu, C.; Ye, Y. Incidence, risk factors, and prognosis of acute exacerbation of rheumatoid arthritis-associated interstitial lung disease: A systematic review and meta-analysis. BMC Pulm. Med. 2023 , 23 , 255. [ Google Scholar ] [ CrossRef ]
• Ley, B.; Ryerson, C.J.; Vittinghoff, E.; Ryu, J.H.; Tomassetti, S.; Lee, J.S.; Poletti, V.; Buccioli, M.; Elicker, B.M.; Jones, K.D.; et al. A Multidimensional Index and Staging System for Idiopathic Pulmonary Fibrosis. Ann. Intern. Med. 2012 , 156 , 684–691. [ Google Scholar ] [ CrossRef ]
• King, T.E., Jr.; Tooze, J.A.; Schwarz, M.I.; Brown, K.R.; Cherniack, R.M. Predicting Survival in Idiopathic Pulmonary Fibrosis: Scoring System and Survival Model. Am. J. Respir. Crit. Care Med. 2001 , 164 , 1171–1181. [ Google Scholar ] [ CrossRef ]
• Bendstrup, E.; Møller, J.; Kronborg-White, S.; Prior, T.S.; Hyldgaard, C. Interstitial Lung Disease in Rheumatoid Arthritis Remains a Challenge for Clinicians. J. Clin. Med. 2019 , 8 , 2038. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Otaola, M.; Paulin, F.; Rosemffet, M.; Balcazar, J.; Perandones, M.; Orausclio, P.; Cazenave, T.; Rossi, S.; Marciano, S.; Schneeberger, E.; et al. Lung ultrasound is a promising screening tool to rule out interstitial lung disease in patients with rheumatoid arthritis. Respirology 2024 , 29 , 588–595. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Bandinelli, F.; Benucci, M.; Mallia, I.; Mauro, I.; Pecani, N.; Li Gobbi, F.; Giannasi, G. Do Ultrasound Lung Abnormalities Correlate to Biomarkers and Male Gender in Rheumatoid Arthritis Patients? A Monocentric Cross-Sectional Study. J. Clin. Med. 2024 , 13 , 3534. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Matteson, E.L.; Kelly, C.; Distler, J.H.W.; Hoffmann-Vold, A.M.; Seibold, J.R.; Mittoo, S.; Dellaripa, P.F.; Aringer, M.; Pope, J.; Distler, O.; et al. Nintedanib in Patients with Autoimmune Disease–Related Progressive Fibrosing Interstitial Lung Diseases: Subgroup Analysis of the INBUILD Trial. Arthritis Rheumatol. 2022 , 74 , 1039–1047. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Page, M.J.; McKenzie, J.E.; Bossuyt, P.M.; Boutron, I.; Hoffmann, T.C.; Mulrow, C.D.; Shamseer, L.; Tetzlaff, J.M.; Akl, E.A.; Brennan, S.E.; et al. The PRISMA 2020 statement: An updated guideline for reporting systematic reviews. BMJ 2021 , 372 , n71. [ Google Scholar ] [ CrossRef ]
• Arnett, F.C.; Edworthy, S.M.; Bloch, D.A.; Mcshane, D.J.; Fries, J.F.; Cooper, N.S.; Healey, L.A.; Kaplan, S.R.; Liang, M.H.; Luthra, H.S.; et al. The american rheumatism association 1987 revised criteria for the classification of rheumatoid arthritis. Arthritis Rheum. 1988 , 31 , 315–324. [ Google Scholar ] [ CrossRef ]
• Aletaha, D.; Neogi, T.; Silman, A.J.; Funovits, J.; Felson, D.T.; Bingham, C.O., 3rd; Birnbaum, N.S.; Burmester, G.R.; Bykerk, V.P.; Cohen, M.D.; et al. 2010 Rheumatoid arthritis classification criteria: An American College of Rheumatology/European League Against Rheumatism collaborative initiative. Arthritis Rheum. 2010 , 62 , 2569–2581. [ Google Scholar ] [ CrossRef ]
• American Thoracic Society; European Respiratory Society. American Thoracic Society/European Respiratory Society International Multidisciplinary Consensus Classification of the Idiopathic Interstitial Pneumonias. This Joint Statement of the American Thoracic Society (ATS), and the European Respiratory Society (ERS) Was Adopted by the ATS Board of Directors, June 2001 and by the ERS Executive Committee, June 2001. Am. J. Respir. Crit. Care Med. 2002 , 165 , 277–304. [ Google Scholar ]
• Travis, W.D.; Costabel, U.; Hansell, D.M.; King, T.E., Jr.; Lynch, D.A.; Nicholson, A.G.; Ryerson, C.J.; Ryu, J.H.; Selman, M.; Wells, A.U.; et al. An Official American Thoracic Society/European Respiratory Society Statement: Update of the International Multidisciplinary Classification of the Idiopathic Interstitial Pneumonias. Am. J. Respir. Crit. Care Med. 2013 , 188 , 733–748. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Flaherty, K.R.; Wells, A.U.; Cottin, V.; Devaraj, A.; Walsh, S.L.; Inoue, Y.; Brown, K.K. Nintedanib in Progressive Fibrosing Interstitial Lung Diseases. N. Engl. J. Med. 2019 , 381 , 1718–1727. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Clark, H.D.; Wells, G.A.; Huët, C.; McAlister, F.A.; Salmi, L.; Fergusson, D.; Laupacis, A. Assessing the Quality of Randomized Trials. Control Clin. Trials 1999 , 20 , 448–452. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Explanation of the 2011 OCEBM Levels of Evidence—Centre for Evidence-Based Medicine (CEBM), University of Oxford. Available online: https://www.cebm.ox.ac.uk/resources/levels-of-evidence/explanation-of-the-2011-ocebm-levels-of-evidence (accessed on 10 August 2024).
• Mena-Vázquez, N.; Redondo-Rodriguez, R.; Rojas-Gimenez, M.; Romero-Barco, C.M.; Fuego-Varela, C.; Perez-Gómez, N.; Añón-Oñate, I.; Castro Pérez, P.; García-Studer, A.; Hidalgo-Conde, A.; et al. Rate of severe and fatal infections in a cohort of patients with interstitial lung disease associated with rheumatoid arthritis: A multicenter prospective study. Front. Immunol. 2024 , 15 , 1341321. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Dixon, W.G.; Hyrich, K.L.; Watson, K.D.; Lunt, M.; BSRBR Control Centre Consortium; Symmons DPM. Influence of anti-TNF therapy on mortality in patients with rheumatoid arthritis-associated interstitial lung disease: Results from the British Society for Rheumatology Biologics Register. Ann. Rheum. Dis. 2010 , 69 , 1086–1091. [ Google Scholar ] [ CrossRef ]
• Koduri, G.; Norton, S.; Young, A.; Cox, N.; Davies, P.; Devlin, J.; Dixey, J.; Gough, A.; Prouse, P.; Winfield, J.; et al. Interstitial lung disease has a poor prognosis in rheumatoid arthritis: Results from an inception cohort. Rheumatology 2010 , 49 , 1483–1489. [ Google Scholar ] [ CrossRef ]
• Wang, Y.; Chen, S.; Zheng, S.; Lin, J.; Hu, S.; Zhuang, J.; Lin, Q.; Xie, X.; Zheng, K.; Zhang, W.; et al. The role of lung ultrasound B-lines and serum KL-6 in the screening and follow-up of rheumatoid arthritis patients for an identification of interstitial lung disease: Review of the literature, proposal for a preliminary algorithm, and clinical application to cases. Arthritis Res. Ther. 2021 , 23 , 212. [ Google Scholar ]
• Mochizuki, T.; Ikari, K.; Yano, K.; Sato, M.; Okazaki, K. Long-term deterioration of interstitial lung disease in patients with rheumatoid arthritis treated with abatacept. Mod. Rheumatol. 2019 , 29 , 413–417. [ Google Scholar ] [ CrossRef ]
• Fotoh, D.S.; Helal, A.; Rizk, M.S.; Esaily, H.A. Serum Krebs von den Lungen-6 and lung ultrasound B lines as potential diagnostic and prognostic factors for rheumatoid arthritis–associated interstitial lung disease. Clin. Rheumatol. 2021 , 40 , 2689–2697. [ Google Scholar ] [ CrossRef ]
• Avouac, J.; Cauvet, A.; Steelandt, A.; Shirai, Y.; Elhai, M.; Kuwana, M.; Distler, O.; Allanore, Y. Improving risk-stratification of rheumatoid arthritis patients for interstitial lung disease. PLoS ONE 2020 , 15 , e0232978. [ Google Scholar ] [ CrossRef ]
• Chen, J.; Chen, Y.; Liu, D.; Lin, Y.; Zhu, L.; Song, S.; Hu, Y.; Liang, T.; Liu, Y.; Liu, W.; et al. Predictors of long-term prognosis in rheumatoid arthritis-related interstitial lung disease. Sci. Rep. 2022 , 12 , 9469. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Solomon, J.J.; Chung, J.H.; Cosgrove, G.P.; Demoruelle, M.K.; Fernandez-Perez, E.R.; Fischer, A.; Frankel, S.K.; Hobbs, S.B.; Huie, T.J.; Ketzer, J.; et al. Predictors of mortality in rheumatoid arthritis-associated interstitial lung disease. Eur. Respir. J. 2016 , 47 , 588–596. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Tyker, A.; Ventura, I.B.; Lee, C.T.; Strykowski, R.; Garcia, N.; Guzy, R.; Jablonski, R.; Vij, R.; Strek, M.E.; Chung, J.H.; et al. High-titer rheumatoid factor seropositivity predicts mediastinal lymphadenopathy and mortality in rheumatoid arthritis-related interstitial lung disease. Sci. Rep. 2021 , 11 , 22821. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Brooks, R.; Baker, J.F.; Yang, Y.; Roul, P.; Kerr, G.S.; Reimold, A.M.; Kunkel, G.; Wysham, K.D.; Singh, N.; Lazaro, D.; et al. The impact of disease severity measures on survival in U.S. veterans with rheumatoid arthritis-associated interstitial lung disease. Rheumatology 2022 , 61 , 4667–4677. [ Google Scholar ] [ CrossRef ]
• Kim, H.C.; Choi, K.H.; Jacob, J.; Song, J.W. Prognostic role of blood KL-6 in rheumatoid arthritis–associated interstitial lung disease. PLoS ONE 2020 , 15 , e0229997. [ Google Scholar ] [ CrossRef ]
• Yamakawa, H.; Sato, S.; Tsumiyama, E.; Nishizawa, T.; Kawabe, R.; Oba, T.; Kamikawa, T.; Horikoshi, M.; Akasaka, K.; Amano, M.; et al. Predictive factors of mortality in rheumatoid arthritis-associated interstitial lung disease analysed by modified HRCT classification of idiopathic pulmonary fibrosis according to the 2018 ATS/ERS/JRS/ALAT criteria. J. Thorac. Dis. 2019 , 11 , 5247–5257. [ Google Scholar ] [ CrossRef ]
• Nurmi, H.M.; Purokivi, M.K.; Kärkkäinen, M.S.; Kettunen, H.P.; Selander, T.A.; Kaarteenaho, R.L. Are risk predicting models useful for estimating survival of patients with rheumatoid arthritis-associated interstitial lung disease? BMC Pulm. Med. 2017 , 17 , 16. [ Google Scholar ] [ CrossRef ]
• Oh, J.H.; Kim, G.H.J.; Cross, G.; Barnett, J.; Jacob, J.; Hong, S.; Song, J.W. Automated quantification system predicts survival in rheumatoid arthritis-associated interstitial lung disease. Rheumatology 2022 , 61 , 4702–4710. [ Google Scholar ] [ CrossRef ]
• Zamora-Legoff, J.A.; Krause, M.L.; Crowson, C.S.; Ryu, J.H.; Matteson, E.L. Progressive Decline of Lung Function in Rheumatoid Arthritis–Associated Interstitial Lung Disease. Arthritis Rheumatol. 2017 , 69 , 542–549. [ Google Scholar ] [ CrossRef ]
• Li, L.; Liu, R.; Zhang, Y.; Zhou, J.; Li, Y.; Xu, Y.; Gao, S.; Zheng, Y. A retrospective study on the predictive implications of clinical characteristics and therapeutic management in patients with rheumatoid arthritis-associated interstitial lung disease. Clin. Rheumatol. 2020 , 39 , 1457–1470. [ Google Scholar ] [ CrossRef ]
• Ito, Y.; Arita, M.; Kumagai, S.; Takei, R.; Noyama, M.; Tokioka, F.; Nishimura, K.; Koyama, T.; Ishida, T. Male Gender and Fibrosis Score on High-Resolution Computed Tomography are Independent Poor Prognostic Factors of Survival in Patients with Rheumatoid Arthritis-Related Interstitial Lung Disease. In Diffuse Parenchymal Lung Disease ; European Respiratory Society: Lausanne, Switzerland, 2017; p. PA887. Available online: http://erj.ersjournals.com/lookup/doi/10.1183/1393003.congress-2017.PA887 (accessed on 13 July 2024).
• Cano-Jiménez, E.; Rodríguez, T.V.; Martín-Robles, I.; Villegas, D.C.; García, J.J.; de Miguel, E.B.; Robles-Pérez, A.; Galván, M.F.; Roibas, C.M.; Lara, S.H.; et al. Diagnostic delay of associated interstitial lung disease increases mortality in rheumatoid arthritis. Sci. Rep. 2021 , 11 , 9184. [ Google Scholar ] [ CrossRef ]
• Dawson, J.K. Predictors of progression of HRCT diagnosed fibrosing alveolitis in patients with rheumatoid arthritis. Ann. Rheum. Dis. 2002 , 61 , 517–521. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Hozumi, H.; Kono, M.; Hasegawa, H.; Kato, S.; Inoue, Y.; Suzuki, Y.; Karayama, M.; Furuhashi, K.; Enomoto, N.; Fujisawa, T.; et al. Acute Exacerbation of Rheumatoid Arthritis-Associated Interstitial Lung Disease: Mortality and Its Prediction Model. Respir. Res. 2022 , 23 , 1–10. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Jacob, J.; Hirani, N.; van Moorsel, C.H.M.; Rajagopalan, S.; Murchison, J.T.; van Es, H.W.; Bartholmai, B.J.; van Beek, F.T.; Struik, M.H.L.; Stewart, G.A.; et al. Predicting outcomes in rheumatoid arthritis related interstitial lung disease. Eur. Respir. J. 2019 , 53 , 1800869. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Izuka, S.; Yamashita, H.; Iba, A.; Takahashi, Y.; Kaneko, H. Acute exacerbation of rheumatoid arthritis–associated interstitial lung disease: Clinical features and prognosis. Rheumatology 2021 , 60 , 2348–2354. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Farquhar, H.J.; Beckert, N.; Beckert, L.; Edwards, A.L.; Matteson, E.L.; Frampton, C.; Stamp, L.K. Survival of adults with rheumatoid arthritis associated interstitial lung disease—A systematic review and meta-analysis. Semin. Arthritis Rheum. 2023 , 60 , 152187. [ Google Scholar ] [ CrossRef ]
• Kim, E.J.; Elicker, B.M.; Maldonado, F.; Webb, W.R.; Ryu, J.H.; Van Uden, J.H.; Lee, J.S.; King, T.E., Jr.; Collard, H.R. Usual interstitial pneumonia in rheumatoid arthritis-associated interstitial lung disease. Eur. Respir. J. 2010 , 35 , 1322–1328. [ Google Scholar ] [ CrossRef ]
• Cassone, G.; Manfredi, A.; Vacchi, C.; Luppi, F.; Coppi, F.; Salvarani, C.; Sebastiani, M. Treatment of Rheumatoid Arthritis-Associated Interstitial Lung Disease: Lights and Shadows. J. Clin. Med. 2020 , 9 , 1082. [ Google Scholar ] [ CrossRef ]
• Venerito, V.; Manfredi, A.; Carletto, A.; Gentileschi, S.; Atzeni, F.; Guiducci, S.; Lavista, M.; La Corte, L.; Pedrollo, E.; Scardapane, A.; et al. Evolution of Rheumatoid-Arthritis-Associated Interstitial Lung Disease in Patients Treated with JAK Inhibitors: A Retrospective Exploratory Study. J. Clin. Med. 2023 , 12 , 957. [ Google Scholar ] [ CrossRef ]
• Tsuchiya, Y.; Takayanagi, N.; Sugiura, H.; Miyahara, Y.; Tokunaga, D.; Kawabata, Y.; Sugita, Y. Lung diseases directly associated with rheumatoid arthritis and their relationship to outcome. Eur. Respir. J. 2011 , 37 , 1411–1417. [ Google Scholar ] [ CrossRef ]
• Mortality and Clinical Features in Rheumatoid Arthritis and Interstitial Lung Disease-ACR Meeting Abstracts. Available online: https://acrabstracts.org/abstract/mortality-and-clinical-features-in-rheumatoid-arthritis-and-interstitial-lung-disease/ (accessed on 15 July 2024).
• Nieto, M.A.; Sanchez-Pernaute, O.; Romero-Bueno, F.; Leon, L.; Vadillo, C.; Freites-Nuñez, D.D.; Jover, J.A.; Álvarez-Sala, J.L.; Abasolo, L. Mortality rate in rheumatoid arthritis-related interstitial lung disease: The role of radiographic patterns. BMC Pulm. Med. 2021 , 21 , 205. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Ekici, M.; Baytar, Y.; Kardas, R.C.; Sari, A.; Akdogan, A.; Durhan, G.; Ariyurek, M.; Kalyoncu, U. Predictors of mortality in rheumatoid arthritis-associated lung disease: A retrospective study on ten years. Jt. Bone Spine 2021 , 88 , 105133. [ Google Scholar ] [ CrossRef ]
• Kakutani, T.; Hashimoto, A.; Tominaga, A.; Kodama, K.; Nogi, S.; Tsuno, H.; Ogihara, H.; Nunokawa, T.; Komiya, A.; Furukawa, H.; et al. Related factors, increased mortality and causes of death in patients with rheumatoid arthritis-associated interstitial lung disease. Mod. Rheumatol. 2020 , 30 , 458–464. [ Google Scholar ] [ CrossRef ]
• Kang, E.H.; Jin, Y.; Desai, R.J.; Liu, J.; Sparks, J.A.; Kim, S.C. Risk of exacerbation of pulmonary comorbidities in patients with rheumatoid arthritis after initiation of abatacept versus TNF inhibitors: A cohort study. Semin. Arthritis Rheum. 2020 , 50 , 401–408. [ Google Scholar ] [ CrossRef ]
• Ng, K.H.; Chen, D.Y.; Lin, C.H.; Chao, W.C.; Chen, H.H. Analysis of risk factors of mortality in rheumatoid arthritis patients with interstitial lung disease: A nationwide, population-based cohort study in Taiwan. RMD Open 2022 , 8 , e002343. [ Google Scholar ] [ CrossRef ]
• Wolfe, F.; Caplan, L.; Michaud, K. Rheumatoid arthritis treatment and the risk of severe interstitial lung disease. Scand. J. Rheumatol. 2007 , 36 , 172–178. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Tanaka, N.; Nishimura, K.; Waki, D.; Kadoba, K.; Murabe, H.; Yokota, T. Annual variation rate of KL-6 for predicting acute exacerbation in patients with rheumatoid arthritis-associated interstitial lung disease. Mod. Rheumatol. 2021 , 31 , 1100–1106. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Akiyama, M.; Kaneko, Y.; Yamaoka, K.; Kondo, H.; Takeuchi, T. Association of disease activity with acute exacerbation of interstitial lung disease during tocilizumab treatment in patients with rheumatoid arthritis: A retrospective, case–control study. Rheumatol. Int. 2016 , 36 , 881–889. [ Google Scholar ] [ CrossRef ]
• Kim, S.H.; Kim, S.Y.; Yoon, H.Y.; Song, J.W. PM 10 increases mortality risk in rheumatoid arthritis-associated interstitial lung disease. RMD Open 2024 , 10 , e003680. [ Google Scholar ] [ CrossRef ]
• Lee, J.S.; Lee, E.Y.; Ha, Y.J.; Kang, E.H.; Lee, Y.J.; Song, Y.W. Serum KL-6 levels reflect the severity of interstitial lung disease associated with connective tissue disease. Arthritis Res. Ther. 2019 , 21 , 58. [ Google Scholar ] [ CrossRef ]
• Kwon, B.S.; Lee, H.Y.; Choe, J.; Chae, E.J.; Hong, S.; Song, J.W. Acute Respiratory Deterioration in Rheumatoid Arthritis-Associated Interstitial Lung Disease. Chest 2022 , 162 , 136–144. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Habib, H.M.; Eisa, A.A.; Arafat, W.R.; Marie, M.A. Pulmonary involvement in early rheumatoid arthritis patients. Clin. Rheumatol. 2011 , 30 , 217–221. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Chang, S.H.; Lee, J.S.; Ha, Y.-J.; Kim, M.U.; Park, C.H.; Lee, J.S.; Kim, J.-W.; Chung, S.W.; Pyo, J.Y.; Lee, S.W.; et al. Lung function trajectory of rheumatoid arthritis–associated interstitial lung disease. Rheumatology 2023 , 62 , 3014–3024. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Courvoisier, D.S.; Chatzidionysiou, K.; Mongin, D.; Lauper, K.; Mariette, X.; Morel, J.; Gottenberg, J.-E.; Bergstra, S.A.; Suarez, M.P.; Codreanu, C.; et al. The impact of seropositivity on the effectiveness of biologic anti-rheumatic agents: Results from a collaboration of 16 registries. Rheumatology 2021 , 60 , 820–828. [ Google Scholar ] [ CrossRef ]
• Marcoux, V.; Lok, S.; Mondal, P.; Assayag, D.; Fisher, J.H.; Shapera, S.; Morisset, J.; Manganas, H.; Fell, C.D.; Hambly, N.; et al. Treatment of Rheumatoid Arthritis-Associated Interstitial Lung Disease in A Multi-Center Registry Cohort. J. Thorac. Dis. 2023 , 15 , 2517. [ Google Scholar ] [ CrossRef ]
• Matson, S.M.; Baqir, M.; Moua, T.; Marll, M.; Kent, J.; Iannazzo, N.S.; Boente, R.D.; Donatelli, J.M.; Dai, J.; Diaz, F.J.; et al. Treatment Outcomes for Rheumatoid Arthritis-Associated Interstitial Lung Disease. Chest 2023 , 163 , 861–869. [ Google Scholar ] [ CrossRef ]
• Pugashetti, J.V.; Adegunsoye, A.; Wu, Z.; Lee, C.T.; Srikrishnan, A.; Ghodrati, S.; Vo, V.; Renzoni, E.A.; Wells, A.U.; Garcia, C.K.; et al. Validation of Proposed Criteria for Progressive Pulmonary Fibrosis. Am. J. Respir. Crit. Care Med. 2023 , 207 , 69–76. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Singh, N.; Varghese, J.; England, B.R.; Solomon, J.J.; Michaud, K.; Mikuls, T.R.; Healy, H.S.; Kimpston, E.M.; Schweizer, M.L. Impact of the pattern of interstitial lung disease on mortality in rheumatoid arthritis: A systematic literature review and meta-analysis. Semin. Arthritis Rheum. 2019 , 49 , 358–365. [ Google Scholar ] [ CrossRef ]
• Franzen, D.; Ciurea, A.; Bratton, D.J.; Clarenbach, C.F.; Latshang, T.D.; Russi, E.W.; Kyburz, D.; Kohler, M. Effect of rituximab on pulmonary function in patients with rheumatoid arthritis. Pulm. Pharmacol. Ther. 2016 , 37 , 24–29. [ Google Scholar ] [ CrossRef ]
• Yusof, Y.M.; Kabia, A.; Darby, M.; Lettieri, G.; Beirne, P.; Vital, E.M.; Dass, S.; Emery, P. Effect of rituximab on the progression of rheumatoid arthritis–related interstitial lung disease: 10 years’ experience at a single centre. Rheumatology 2017 , 56 , 1348–1357. [ Google Scholar ] [ CrossRef ]
• Kurata, I.; Tsuboi, H.; Terasaki, M.; Shimizu, M.; Toko, H.; Honda, F.; Ohyama, A.; Yagishita, M.; Osada, A.; Ebe, H.; et al. Effect of Biological Disease-modifying Anti-rheumatic Drugs on Airway and Interstitial Lung Disease in Patients with Rheumatoid Arthritis. Intern. Med. 2019 , 58 , 1703–1712. [ Google Scholar ] [ CrossRef ]
• Hyldgaard, C.; Hilberg, O.; Pedersen, A.B.; Ulrichsen, S.P.; Løkke, A.; Bendstrup, E.; Ellingsen, T. A population-based cohort study of rheumatoid arthritis-associated interstitial lung disease: Comorbidity and mortality. Ann. Rheum. Dis. 2017 , 76 , 1700–1706. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Song, J.W.; Lee, H.K.; Lee, C.K.; Chae, E.J.; Jang, S.J.; Colby, T.V.; Kim, D.S. Clinical Course and Outcome of Rheumatoid Arthritis-Related Usual Interstitial Pneumonia. Sarcoidosis Vasc. Diffuse. Lung Dis. 2013 , 30 , 103–112. [ Google Scholar ]
• Kelly, C.A.; Nisar, M.; Arthanari, S.; Carty, S.; Woodhead, F.A.; Price-Forbes, A.; Middleton, D.; Dempsey, O.; Miller, D.; Basu, N.; et al. Rheumatoid arthritis related interstitial lung disease—Improving outcomes over 25 years: A large multicentre UK study. Rheumatology 2021 , 60 , 1882–1890. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Juge, P.A.; Hayashi, K.; McDermott, G.C.; Vanni, K.M.M.; Kowalski, E.; Qian, G.; Bade, K.; Saavedra, A.; Dieudé, P.; Dellaripa, P.F.; et al. Effectiveness and tolerability of antifibrotics in rheumatoid arthritis-associated interstitial lung disease. Semin. Arthritis Rheum. 2024 , 64 , 152312. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Rojas-Serrano, J.; Herrera-Bringas, D.; Pérez-Román, D.I.; Pérez-Dorame, R.; Mateos-Toledo, H.; Mejía, M. Rheumatoid arthritis-related interstitial lung disease (RA-ILD): Methotrexate and the severity of lung disease are associated to prognosis. Clin. Rheumatol. 2017 , 36 , 1493–1500. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Yamakawa, H.; Ogura, T.; Kameda, H.; Kishaba, T.; Iwasawa, T.; Takemura, T.; Kuwano, K. Decision-Making Strategy for the Treatment of Rheumatoid Arthritis-Associated Interstitial Lung Disease (RA-ILD). J. Clin. Med. 2021 , 10 , 3806. [ Google Scholar ] [ CrossRef ]

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Groseanu, L.; Niță, C. A Systematic Review of the Key Predictors of Progression and Mortality of Rheumatoid Arthritis-Associated Interstitial Lung Disease. Diagnostics 2024 , 14 , 1890. https://doi.org/10.3390/diagnostics14171890

Groseanu L, Niță C. A Systematic Review of the Key Predictors of Progression and Mortality of Rheumatoid Arthritis-Associated Interstitial Lung Disease. Diagnostics . 2024; 14(17):1890. https://doi.org/10.3390/diagnostics14171890

Groseanu, Laura, and Cristina Niță. 2024. "A Systematic Review of the Key Predictors of Progression and Mortality of Rheumatoid Arthritis-Associated Interstitial Lung Disease" Diagnostics 14, no. 17: 1890. https://doi.org/10.3390/diagnostics14171890

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1.1: Review of Functions

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Learning Objectives

• Use functional notation to evaluate a function.
• Determine the domain and range of a function.
• Draw the graph of a function.
• Find the zeros of a function.
• Recognize a function from a table of values.
• Make new functions from two or more given functions.
• Describe the symmetry properties of a function.

In this section, we provide a formal definition of a function and examine several ways in which functions are represented—namely, through tables, formulas, and graphs. We study formal notation and terms related to functions. We also define composition of functions and symmetry properties. Most of this material will be a review for you, but it serves as a handy reference to remind you of some of the algebraic techniques useful for working with functions.

Given two sets \(A\) and \(B\) a set with elements that are ordered pairs \((x,y)\) where \(x\) is an element of \(A\) and \(y\) is an element of \(B,\) is a relation from \(A\) to \(B\). A relation from \(A\) to \(B\) defines a relationship between those two sets. A function is a special type of relation in which each element of the first set is related to exactly one element of the second set. The element of the first set is called the input ; the element of the second set is called the output . Functions are used all the time in mathematics to describe relationships between two sets. For any function, when we know the input, the output is determined, so we say that the output is a function of the input. For example, the area of a square is determined by its side length, so we say that the area (the output) is a function of its side length (the input). The velocity of a ball thrown in the air can be described as a function of the amount of time the ball is in the air. The cost of mailing a package is a function of the weight of the package. Since functions have so many uses, it is important to have precise definitions and terminology to study them.

Definition: Functions

A function \(f\) consists of a set of inputs, a set of outputs, and a rule for assigning each input to exactly one output. The set of inputs is called the domain of the function. The set of outputs is called the range of the function .

For example, consider the function \(f\), where the domain is the set of all real numbers and the rule is to square the input. Then, the input \(x=3\) is assigned to the output \(3^2=9\).

Since every nonnegative real number has a real-value square root, every nonnegative number is an element of the range of this function. Since there is no real number with a square that is negative, the negative real numbers are not elements of the range. We conclude that the range is the set of nonnegative real numbers.

For a general function \(f\) with domain \(D\), we often use \(x\) to denote the input and \(y\) to denote the output associated with \(x\). When doing so, we refer to \(x\) as the independent variable and \(y\) as the dependent variable , because it depends on \(x\). Using function notation, we write \(y=f(x)\), and we read this equation as “\(y\) equals \(f\) of \(x.”\) For the squaring function described earlier, we write \(f(x)=x^2\).

The concept of a function can be visualized using Figures \(\PageIndex{1}\) - \(\PageIndex{3}\).

We can also visualize a function by plotting points \((x,y)\) in the coordinate plane where \(y=f(x)\). The graph of a function is the set of all these points. For example, consider the function \(f\), where the domain is the set \(D=\{1,2,3\}\) and the rule is \(f(x)=3−x\). In Figure \(\PageIndex{4}\), we plot a graph of this function.

Every function has a domain. However, sometimes a function is described by an equation, as in \(f(x)=x^2\), with no specific domain given. In this case, the domain is taken to be the set of all real numbers \(x\) for which \(f(x)\) is a real number. For example, since any real number can be squared, if no other domain is specified, we consider the domain of \(f(x)=x^2\) to be the set of all real numbers. On the other hand, the square root function \(f(x)=\sqrt{x}\) only gives a real output if \(x\) is nonnegative. Therefore, the domain of the function \(f(x)=\sqrt{x}\) is the set of nonnegative real numbers, sometimes called the natural domain.

For the functions \(f(x)=x^2\) and \(f(x)=\sqrt{x}\), the domains are sets with an infinite number of elements. Clearly we cannot list all these elements. When describing a set with an infinite number of elements, it is often helpful to use set-builder or interval notation. When using set-builder notation to describe a subset of all real numbers, denoted \(R\), we write

\[\{x\,|\,\textit{x has some property}\}. \nonumber \]

We read this as the set of real numbers \(x\) such that \(x\) has some property. For example, if we were interested in the set of real numbers that are greater than one but less than five, we could denote this set using set-builder notation by writing

\[\{x\,|\,1<x<5\}.\nonumber \]

A set such as this, which contains all numbers greater than \(a\) and less than \(b,\) can also be denoted using the interval notation \((a,b)\). Therefore,

\[(1,5)=\{x\,|\,1<x<5\}.\nonumber \]

The numbers \(1\) and \(5\) are called the endpoints of this set. If we want to consider the set that includes the endpoints, we would denote this set by writing

\[[1,5]=\{x\,|\,1 \le x \le 5\}.\nonumber \]

We can use similar notation if we want to include one of the endpoints, but not the other. To denote the set of nonnegative real numbers, we would use the set-builder notation

\[\{x\,|\,x\ge 0\}.\nonumber \]

The smallest number in this set is zero, but this set does not have a largest number. Using interval notation, we would use the symbol \(∞,\) which refers to positive infinity, and we would write the set as

\[[0,∞)=\{x\,|\,x\ge 0\}.\nonumber \]

It is important to note that \(∞\) is not a real number. It is used symbolically here to indicate that this set includes all real numbers greater than or equal to zero. Similarly, if we wanted to describe the set of all nonpositive numbers, we could write

\[(−∞,0]=\{x\,|\,x≤0\}.\nonumber \]

Here, the notation \(−∞\) refers to negative infinity, and it indicates that we are including all numbers less than or equal to zero, no matter how small. The set

\[(−∞,∞)=\{\textit{x} \,|\, \textit{x is any real number}\}\nonumber \]

refers to the set of all real numbers. Some functions are defined using different equations for different parts of their domain. These types of functions are known as piecewise-defined functions. For example, suppose we want to define a function \(f\) with a domain that is the set of all real numbers such that \(f(x)=3x+1\) for \(x≥2\) and \(f(x)=x^2\) for \( x<2\). We denote this function by writing

\[f(x)=\begin{cases} 3x+1, & \text{if } x≥2 \\ x^2, & \text{if } x<2 \end{cases}\nonumber \]

When evaluating this function for an input \(x\), the equation to use depends on whether \(x≥2\) or \(x<2\). For example, since \(5>2\), we use the fact that \(f(x)=3x+1\) for \(x≥2\) and see that \(f(5)=3(5)+1=16\). On the other hand, for \(x=−1\), we use the fact that \(f(x)=x^2\) for \(x<2\) and see that \(f(−1)=1\).

Example \(\PageIndex{1}\): Evaluating Functions

For the function \(f(x)=3x^2+2x−1\), evaluate:

• \(f(−2)\)
• \(f(\sqrt{2})\)

Substitute the given value for \(x\) in the formula for \(f(x)\).

• \(f(−2)=3(−2)^2+2(−2)−1=12−4−1=7\)
• \(f(\sqrt{2})=3(\sqrt{2})^2+2\sqrt{2}−1=6+2\sqrt{2}−1=5+2\sqrt{2}\)
• \(f(a+h)=3(a+h)^2+2(a+h)−1=3(a^2+2ah+h^2)+2a+2h−1=3a^2+6ah+3h^2+2a+2h−1\)

Exercise \(\PageIndex{1}\)

For \(f(x)=x^2−3x+5\), evaluate \(f(1)\) and \(f(a+h)\).

Substitute \(1\) and \(a+h\) for \(x\) in the formula for \(f(x)\).

\(f(1)=3 \) and \(f(a+h)=a^2+2ah+h^2−3a−3h+5\)

Example \(\PageIndex{2}\): Finding Domain and Range

For each of the following functions, determine the i. domain and ii. range.

• \(f(x)=(x−4)^2+5\)
• \(f(x)=\sqrt{3x+2}−1\)
• \(f(x)=\dfrac{3}{x−2}\)

a. Consider \(f(x)=(x−4)^2+5.\)

1.Since \(f(x)=(x−4)^2+5\) is a real number for any real number \(x\), the domain of \(f\) is the interval \((−∞,∞)\).

2. Since \((x−4)^2≥0\), we know \(f(x)=(x−4)^2+5≥5\). Therefore, the range must be a subset of \(\{y\,|\,y≥5\}.\) To show that every element in this set is in the range, we need to show that for a given \(y\) in that set, there is a real number \(x\) such that \(f(x)=(x−4)^2+5=y\). Solving this equation for \(x,\) we see that we need \(x\) such that

\((x−4)^2=y−5.\)

This equation is satisfied as long as there exists a real number \(x\) such that

\(x−4=±\sqrt{y−5}\)

Since \(y≥5\), the square root is well-defined. We conclude that for \(x=4±\sqrt{y−5},\) \(f(x)=y,\) and therefore the range is \(\{y\,|\,y≥5 \}.\)

b. Consider \(f(x)=\sqrt{3x+2}−1\).

1.To find the domain of \(f\), we need the expression \(3x+2≥0\). Solving this inequality, we conclude that the domain is \(\{x\,|\,x≥−2/3\}.\)

2.To find the range of \(f\), we note that since \(\sqrt{3x+2}≥0,\) \(f(x)=\sqrt{3x+2}−1≥−1\). Therefore, the range of \(f\) must be a subset of the set \(\{y\,|\,y≥−1\}\). To show that every element in this set is in the range of \(f\), we need to show that for all \(y\) in this set, there exists a real number \(x\) in the domain such that \(f(x)=y.\) Let \(y≥−1.\) Then, \(f(x)=y\) if and only if

\(\sqrt{3x+2}−1=y.\)

Solving this equation for \(x,\) we see that \(x\) must solve the equation

\(\sqrt{3x+2}=y+1.\)

Since \(y≥−1\), such an \(x\) could exist. Squaring both sides of this equation, we have \(3x+2=(y+1)^2.\)

Therefore, we need

\(3x=(y+1)^2−2,\)

which implies

\(x=\frac{1}{3}(y+1)^2−\frac{2}{3}.\)

We just need to verify that \(x\) is in the domain of \(f\). Since the domain of \(f\) consists of all real numbers greater than or equal to \(\frac{−2}{3}\), and

\(\frac{1}{3}(y+1)^2-\frac{2}{3}≥−\frac{2}{3},\)

there does exist an \(x\) in the domain of \(f\). We conclude that the range of \(f\) is \(\{y\,|\,y≥−1\}.\)

c. Consider \(f(x)=\dfrac{3}{x−2}.\)

1.Since \(3/(x−2)\) is defined when the denominator is nonzero, the domain is \(\{x\,|\,x≠2\}.\)

2.To find the range of \(f,\) we need to find the values of \(y\) such that there exists a real number \(x\) in the domain with the property that

\(\dfrac{3}{x−2}=y.\)

Solving this equation for \(x,\) we find that

\(x=\dfrac{3}{y}+2.\)

Therefore, as long as \(y≠0\), there exists a real number \(x\) in the domain such that \(f(x)=y\). Thus, the range is \(\{y\,|\,y≠0\}.\)

Exercise \(\PageIndex{2}\)

Find the domain and range for \(f(x)=\sqrt{4−2x}+5.\)

Use \(4−2x≥0\).

Domain = \(\{x\,|\,x≤2\}\) and range = \(\{y\,|\,y≥5\}\)

Representing Functions

Typically, a function is represented using one or more of the following tools:

We can identify a function in each form, but we can also use them together. For instance, we can plot on a graph the values from a table or create a table from a formula.

Functions described using a table of values arise frequently in real-world applications. Consider the following simple example. We can describe temperature on a given day as a function of time of day. Suppose we record the temperature every hour for a 24-hour period starting at midnight. We let our input variable \(x\) be the time after midnight, measured in hours, and the output variable \(y\) be the temperature \(x\) hours after midnight, measured in degrees Fahrenheit. We record our data in Table \(\PageIndex{1}\).

We can see from the table that temperature is a function of time, and the temperature decreases, then increases, and then decreases again. However, we cannot get a clear picture of the behavior of the function without graphing it.

Given a function \(f\) described by a table, we can provide a visual picture of the function in the form of a graph. Graphing the temperatures listed in Table \(\PageIndex{1}\) can give us a better idea of their fluctuation throughout the day. Figure \(\PageIndex{5}\) shows the plot of the temperature function.

From the points plotted on the graph in Figure \(\PageIndex{5}\), we can visualize the general shape of the graph. It is often useful to connect the dots in the graph, which represent the data from the table. In this example, although we cannot make any definitive conclusion regarding what the temperature was at any time for which the temperature was not recorded, given the number of data points collected and the pattern in these points, it is reasonable to suspect that the temperatures at other times followed a similar pattern, as we can see in Figure \(\PageIndex{6}\).

Algebraic Formulas

Sometimes we are not given the values of a function in table form, rather we are given the values in an explicit formula. Formulas arise in many applications. For example, the area of a circle of radius \(r\) is given by the formula \(A(r)=πr^2\). When an object is thrown upward from the ground with an initial velocity \(v_{0}\) ft/s, its height above the ground from the time it is thrown until it hits the ground is given by the formula \(s(t)=−16t^2+v_{0}t\). When \(P\) dollars are invested in an account at an annual interest rate \(r\) compounded continuously, the amount of money after \(t\) years is given by the formula \(A(t)=Pe^{rt}\). Algebraic formulas are important tools to calculate function values. Often we also represent these functions visually in graph form.

Given an algebraic formula for a function \(f\), the graph of \(f\) is the set of points \((x,f(x))\), where \(x\) is in the domain of \(f\) and \(f(x)\) is in the range. To graph a function given by a formula, it is helpful to begin by using the formula to create a table of inputs and outputs. If the domain of \(f\) consists of an infinite number of values, we cannot list all of them, but because listing some of the inputs and outputs can be very useful, it is often a good way to begin.

When creating a table of inputs and outputs, we typically check to determine whether zero is an output. Those values of \(x\) where \(f(x)=0\) are called the zeros of a function. For example, the zeros of \(f(x)=x^2−4\) are \(x=±2\). The zeros determine where the graph of \(f\) intersects the \(x\)-axis, which gives us more information about the shape of the graph of the function. The graph of a function may never intersect the \(x\)-axis, or it may intersect multiple (or even infinitely many) times.

Another point of interest is the \(y\) -intercept, if it exists. The \(y\)-intercept is given by \((0,f(0))\).

Since a function has exactly one output for each input, the graph of a function can have, at most, one \(y\)-intercept. If \(x=0\) is in the domain of a function \(f,\) then \(f\) has exactly one \(y\)-intercept. If \(x=0\) is not in the domain of \(f,\) then \(f\) has no \(y\)-intercept. Similarly, for any real number \(c,\) if \(c\) is in the domain of \(f\), there is exactly one output \(f(c),\) and the line \(x=c\) intersects the graph of \(f\) exactly once. On the other hand, if \(c\) is not in the domain of \(f,\) \(f(c)\) is not defined and the line \(x=c\) does not intersect the graph of \(f\). This property is summarized in the vertical line test.

Vertical Line Test

Given a function \(f\), every vertical line that may be drawn intersects the graph of \(f\) no more than once. If any vertical line intersects a set of points more than once, the set of points does not represent a function.

We can use this test to determine whether a set of plotted points represents the graph of a function (Figure \(\PageIndex{7}\)).

Example \(\PageIndex{3}\): Finding Zeros and \(y\)-Intercepts of a Function

Consider the function \(f(x)=−4x+2.\)

• Find all zeros of \(f\).
• Find the \(y\)-intercept (if any).
• Sketch a graph of \(f\).

1.To find the zeros, solve \(f(x)=−4x+2=0\). We discover that \(f\) has one zero at \(x=1/2\).

2. The \(y\)-intercept is given by \((0,f(0))=(0,2).\)

3. Given that \(f\) is a linear function of the form \(f(x)=mx+b\) that passes through the points \((1/2,0)\) and \((0,2)\), we can sketch the graph of \(f\) (Figure \(\PageIndex{8}\)).

Example \(\PageIndex{4}\): Using Zeros and \(y\)-Intercepts to Sketch a Graph

Consider the function \(f(x)=\sqrt{x+3}+1\).

1.To find the zeros, solve \(\sqrt{x+3}+1=0\). This equation implies \(\sqrt{x+3}=−1\). Since \(\sqrt{x+3}≥0\) for all \(x\), this equation has no solutions, and therefore \(f\) has no zeros.

2.The \(y\)-intercept is given by \((0,f(0))=(0,\sqrt{3}+1)\).

3.To graph this function, we make a table of values. Since we need \(x+3≥0\), we need to choose values of \(x≥−3\). We choose values that make the square-root function easy to evaluate.

Making use of the table and knowing that, since the function is a square root, the graph of \(f\) should be similar to the graph of \(y=\sqrt{x}\), we sketch the graph (Figure \(\PageIndex{9}\)).

Exercise \(\PageIndex{4}\)

Find the zeros of \(f(x)=x^3−5x^2+6x.\)

Factor the polynomial.

\(x=0,2,3\)

Example \(\PageIndex{5}\): Finding the Height of a Free-Falling Object

If a ball is dropped from a height of 100 ft, its height s at time \(t\) is given by the function \(s(t)=−16t^2+100\), where s is measured in feet and \(t\) is measured in seconds. The domain is restricted to the interval \([0,c],\) where \(t=0\) is the time when the ball is dropped and \(t=c\) is the time when the ball hits the ground.

• Create a table showing the height s(t) when \(t=0,\, 0.5,\, 1,\, 1.5,\, 2,\) and \(2.5\). Using the data from the table, determine the domain for this function. That is, find the time \(c\) when the ball hits the ground.
• Sketch a graph of \(s\).

Since the ball hits the ground when \(t=2.5\), the domain of this function is the interval \([0,2.5]\).

Definition: Increasing and Decreasing on an Interval

We say that a function \(f\) is increasing on the interval \(I\) if for all \(x_{1},\, x_{2}∈I,\)

\(f(x_{1})≤f(x_{2})\) when \(x_{1}<x_{2}.\)

We say \(f\) is strictly increasing on the interval \(I\) if for all \(x_{1},x_{2}∈I,\)

\(f(x_{1})<f(x_{2})\) when \(x_{1}<x_{2}.\)

We say that a function \(f\) is decreasing on the interval \(I\) if for all \(x_{1},x_{2}∈I,\)

\(f(x_{1})≥f(x_{2})\) if \(x_{1}<x_{2}.\)

We say that a function \(f\) is strictly decreasing on the interval \(I\) if for all \(x_{1},x_{2}∈I\),

\(f(x_{1})>f(x_{2})\) if \(x_{1}<x_{2}.\)

For example, the function \(f(x)=3x\) is increasing on the interval \((−∞,∞)\) because \(3x_{1}<3x_{2}\) whenever \(x_{1}<x_{2}\). On the other hand, the function \(f(x)=−x^3\) is decreasing on the interval \((−∞,∞)\) because \(−x^3_{1}>−x^3_{2}\) whenever \(x_{1}<x_{2}\) (Figure \(\PageIndex{10}\)).

Combining Functions

Now that we have reviewed the basic characteristics of functions, we can see what happens to these properties when we combine functions in different ways, using basic mathematical operations to create new functions. For example, if the cost for a company to manufacture \(x\) items is described by the function \(C(x)\) and the revenue created by the sale of \(x\) items is described by the function \(R(x)\), then the profit on the manufacture and sale of \(x\) items is defined as \(P(x)=R(x)−C(x)\). Using the difference between two functions, we created a new function.

Alternatively, we can create a new function by composing two functions. For example, given the functions \(f(x)=x^2\) and \(g(x)=3x+1\), the composite function \(f∘g\) is defined such that

\[(f∘g)(x)=f(g(x))=(g(x))^2=(3x+1)^2. \nonumber \]

The composite function \(g∘f\) is defined such that

\[(g∘f)(x)=g(f(x))=3f(x)+1=3x^2+1. \nonumber \]

Note that these two new functions are different from each other.

Combining Functions with Mathematical Operators

To combine functions using mathematical operators, we simply write the functions with the operator and simplify. Given two functions \(f\) and \(g\), we can define four new functions:

Example \(\PageIndex{6}\): Combining Functions Using Mathematical Operations

Given the functions \(f(x)=2x−3\) and \(g(x)=x^2−1\), find each of the following functions and state its domain.

• \((f+g)(x)\)
• \((f−g)(x)\)
• \((f·g)(x)\)
• \(\left(\dfrac{f}{g}\right)(x)\)

1. \((f+g)(x)=(2x−3)+(x^2−1)=x^2+2x−4.\)

The domain of this function is the interval \((−∞,∞)\).

2.\((f−g)(x)=(2x−3)−(x^2−1)=−x^2+2x−2.\)

3. \((f·g)(x)=(2x−3)(x^2−1)=2x^3−3x^2−2x+3.\)

4. \(\left(\dfrac{f}{g}\right)(x)=\dfrac{2x−3}{x^2−1}\).

The domain of this function is \(\{x\,|\,x≠±1\}.\)

Exercise \(\PageIndex{6}\)

For \(f(x)=x^2+3\) and \(g(x)=2x−5\), find \((f/g)(x)\) and state its domain.

The new function \((f/g)(x)\) is a quotient of two functions. For what values of \(x\) is the denominator zero?

\(\left(\dfrac{f}{g}\right)(x)=\frac{x^2+3}{2x−5}.\) The domain is \(\{x\,|\,x≠\frac{5}{2}\}.\)

Function Composition

When we compose functions, we take a function of a function. For example, suppose the temperature \(T\) on a given day is described as a function of time \(t\) (measured in hours after midnight) as in Table \(\PageIndex{1}\). Suppose the cost \(C\), to heat or cool a building for 1 hour, can be described as a function of the temperature \(T\). Combining these two functions, we can describe the cost of heating or cooling a building as a function of time by evaluating \(C(T(t))\). We have defined a new function, denoted \(C∘T\), which is defined such that \((C∘T)(t)=C(T(t))\) for all \(t\) in the domain of \(T\). This new function is called a composite function. We note that since cost is a function of temperature and temperature is a function of time, it makes sense to define this new function \((C∘T)(t)\). It does not make sense to consider \((T∘C)(t)\), because temperature is not a function of cost.

Definition: Composite Functions

Consider the function \(f\) with domain \(A\) and range \(B\), and the function \(g\) with domain \(D\) and range \(E\). If \(B\) is a subset of \(D\), then the composite function \((g∘f)(x)\) is the function with domain \(A\) such that

\[(g∘f)(x)=g(f(x)) \nonumber \]

A composite function \(g∘f\) can be viewed in two steps. First, the function \(f\) maps each input \(x\) in the domain of \(f\) to its output \(f(x)\) in the range of \(f\). Second, since the range of \(f\) is a subset of the domain of \(g\), the output \(f(x)\) is an element in the domain of \(g\), and therefore it is mapped to an output \(g(f(x))\) in the range of \(g\). In Figure \(\PageIndex{11}\), we see a visual image of a composite function.

Example \(\PageIndex{7}\): Compositions of Functions Defined by Formulas

Consider the functions \(f(x)=x^2+1\) and \(g(x)=1/x\).

• Find \((g∘f)(x)\) and state its domain and range.
• Evaluate \((g∘f)(4),\) \((g∘f)(−1/2)\).
• Find \((f∘g)(x)\) and state its domain and range.
• Evaluate \((f∘g)(4),\) \((f∘g)(−1/2)\).

1. We can find the formula for \((g∘f)(x)\) in two different ways. We could write

\((g∘f)(x)=g(f(x))=g(x^2+1)=\dfrac{1}{x^2+1}\).

Alternatively, we could write

\((g∘f)(x)=g(f(x))=\dfrac{1}{f(x)}=\dfrac{1}{x^2+1}.\)

Since \(x^2+1≠0\) for all real numbers \(x,\) the domain of \((g∘f)(x)\) is the set of all real numbers. Since \(0<1/(x^2+1)≤1\), the range is, at most, the interval \((0,1]\). To show that the range is this entire interval, we let \(y=1/(x^2+1)\) and solve this equation for \(x\) to show that for all \(y\) in the interval \((0,1]\), there exists a real number \(x\) such that \(y=1/(x^2+1)\). Solving this equation for \(x,\) we see that \(x^2+1=1/y\), which implies that

\(x=±\sqrt{\frac{1}{y}−1}\)

If \(y\) is in the interval \((0,1]\), the expression under the radical is nonnegative, and therefore there exists a real number \(x\) such that \(1/(x^2+1)=y\). We conclude that the range of \(g∘f\) is the interval \((0,1].\)

2. \((g∘f)(4)=g(f(4))=g(4^2+1)=g(17)=\frac{1}{17}\)

\((g∘f)(−\frac{1}{2})=g(f(−\frac{1}{2}))=g((−\frac{1}{2})^2+1)=g(\frac{5}{4})=\frac{4}{5}\)

3. We can find a formula for \((f∘g)(x)\) in two ways. First, we could write

\((f∘g)(x)=f(g(x))=f(\frac{1}{x})=(\frac{1}{x})^2+1.\)

\((f∘g)(x)=f(g(x))=(g(x))^2+1=(\frac{1}{x})^2+1.\)

The domain of \(f∘g\) is the set of all real numbers \(x\) such that \(x≠0\). To find the range of \(f,\) we need to find all values \(y\) for which there exists a real number \(x≠0\) such that

\(\left(\dfrac{1}{x}\right)^2+1=y.\)

Solving this equation for \(x,\) we see that we need \(x\) to satisfy

\(\left(\dfrac{1}{x}\right)^2=y−1,\)

which simplifies to

\(\dfrac{1}{x}=±\sqrt{y−1}\)

Finally, we obtain

\(x=±\dfrac{1}{\sqrt{y−1}}.\)

Since \(1/\sqrt{y−1}\) is a real number if and only if \(y>1,\) the range of \(f\) is the set \(\{y\,|\,y≥1\}.\)

4.\((f∘g)(4)=f(g(4))=f(\frac{1}{4})=(\frac{1}{4})^2+1=\frac{17}{16}\)

\((f∘g)(−\frac{1}{2})=f(g(−\frac{1}{2}))=f(−2)=(−2)^2+1=5\)

In Example \(\PageIndex{7}\) , we can see that \((f∘g)(x)≠(g∘f)(x)\). This tells us, in general terms, that the order in which we compose functions matters.

Exercise \(\PageIndex{7}\)

Let \(f(x)=2−5x\). Let \(g(x)=\sqrt{x}.\) Find \((f∘g)(x)\).

\((f∘g)(x)=2−5\sqrt{x}.\)

Example \(\PageIndex{8}\): Composition of Functions Defined by Tables

Consider the functions \(f\) and \(g\) described by

• Evaluate \((g∘f)(3)\),\((g∘f)(0)\).
• State the domain and range of \((g∘f)(x)\).
• Evaluate \((f∘f)(3)\),\((f∘f)(1)\).
• State the domain and range of \((f∘f)(x)\).

1. \((g∘f)(3)=g(f(3))=g(−2)=0\)

\((g∘f)(0)=g(4)=5\)

2.The domain of \(g∘f\) is the set \(\{−3,−2,−1,0,1,2,3,4\}.\) Since the range of \(f\) is the set \(\{−2,0,2,4\},\) the range of \(g∘f\) is the set \(\{0,3,5\}.\)

3. \((f∘f)(3)=f(f(3))=f(−2)=4\)

\((f∘f)(1)=f(f(1))=f(−2)=4\)

4.The domain of \(f∘f\) is the set \(\{−3,−2,−1,0,1,2,3,4\}.\) Since the range of \(f\) is the set \(\{−2,0,2,4\},\) the range of \(f∘f\) is the set \(\{0,4\}.\)

Example \(\PageIndex{9}\): Application Involving a Composite Function

A store is advertising a sale of 20% off all merchandise. Caroline has a coupon that entitles her to an additional 15% off any item, including sale merchandise. If Caroline decides to purchase an item with an original price of \(x\) dollars, how much will she end up paying if she applies her coupon to the sale price? Solve this problem by using a composite function.

Since the sale price is 20% off the original price, if an item is \(x\) dollars, its sale price is given by \(f(x)=0.80x\). Since the coupon entitles an individual to 15% off the price of any item, if an item is \(y\) dollars, the price, after applying the coupon, is given by g(y)=0.85y. Therefore, if the price is originally \(x\) dollars, its sale price will be \(f(x)=0.80x\) and then its final price after the coupon will be \(g(f(x))=0.85(0.80x)=0.68x\).

Exercise \(\PageIndex{9}\)

If items are on sale for 10% off their original price, and a customer has a coupon for an additional 30% off, what will be the final price for an item that is originally \(x\) dollars, after applying the coupon to the sale price?

The sale price of an item with an original price of \(x\) dollars is \(f(x)=0.90x\). The coupon price for an item that is \(y\) dollars is \(g(y)=0.70y\).

\((g∘f)(x)=0.63x\)

Symmetry of Functions

The graphs of certain functions have symmetry properties that help us understand the function and the shape of its graph. For example, consider the function \(f(x)=x^4−2x^2−3\) shown in Figure \(\PageIndex{12a}\). If we take the part of the curve that lies to the right of the \(y\)-axis and flip it over the \(y\)-axis, it lays exactly on top of the curve to the left of the \(y\)-axis. In this case, we say the function has symmetry about the \(y\)-axis . On the other hand, consider the function \(f(x)=x^3−4x\) shown in Figure \(\PageIndex{12b}\). If we take the graph and rotate it \(180°\) about the origin, the new graph will look exactly the same. In this case, we say the function has symmetry about the origin .

If we are given the graph of a function, it is easy to see whether the graph has one of these symmetry properties. But without a graph, how can we determine algebraically whether a function \(f\) has symmetry? Looking at Figure \(\PageIndex{12a}\) again, we see that since \(f\) is symmetric about the \(y\)-axis, if the point \((x,y)\) is on the graph, the point \((−x,y)\) is on the graph. In other words, \(f(−x)=f(x)\). If a function \(f\) has this property, we say \(f\) is an even function, which has symmetry about the \(y\)-axis. For example, \(f(x)=x^2\) is even because

\(f(−x)=(−x)^2=x^2=f(x).\)

In contrast, looking at Figure \(\PageIndex{12b}\) again, if a function \(f\) is symmetric about the origin, then whenever the point \((x,y)\) is on the graph, the point \((−x,−y)\) is also on the graph. In other words, \(f(−x)=−f(x)\). If \(f\) has this property, we say \(f\) is an odd function, which has symmetry about the origin. For example, \(f(x)=x^3\) is odd because

\(f(−x)=(−x)^3=−x^3=−f(x).\)

Definition: Even and Odd Functions

• If \(f(x)=f(−x)\) for all \(x\) in the domain of \(f\), then \(f\) is an even function. An even function is symmetric about the \(y\)-axis.
• If \(f(−x)=−f(x)\) for all \(x\) in the domain of \(f\), then \(f\) is an odd function. An odd function is symmetric about the origin.

Example \(\PageIndex{10}\): Even and Odd Functions

Determine whether each of the following functions is even, odd, or neither.

• \(f(x)=−5x^4+7x^2−2\)
• \(f(x)=2x^5−4x+5\)
• \(f(x)=\frac{3x}{x^2+1}\)

To determine whether a function is even or odd, we evaluate \(f(−x)\) and compare it to \(f(x)\) and \(−f(x)\).

1. \(f(−x)=−5(−x)^4+7(−x)^2−2=−5x^4+7x^2−2=f(x).\) Therefore, \(f\) is even.

2.\(f(−x)=2(−x)^5−4(−x)+5=−2x^5+4x+5.\) Now, \(f(−x)≠f(x).\) Furthermore, noting that \(−f(x)=−2x^5+4x−5\), we see that \(f(−x)≠−f(x)\). Therefore, \(f\) is neither even nor odd.

3.\(f(−x)=3(−x)/((−x)2+1)\)\(=−3x/(x^2+1)=\)\(−[3x/(x^2+1)]=−f(x).\) Therefore, \(f\) is odd.

Exercise \(\PageIndex{10}\)

Determine whether \(f(x)=4x^3−5x\) is even, odd, or neither.

Compare \(f(−x)\) with \(f(x)\) and \(−f(x)\).

\(f(x)\) is odd.

One symmetric function that arises frequently is the absolute value function , written as \(|x|\). The absolute value function is defined as

\[f(x)=\begin{cases} -x, & \text{if }x<0 \\ x, & \text{if } x≥0 \end{cases} \nonumber \]

Some students describe this function by stating that it “makes everything positive.” By the definition of the absolute value function, we see that if \(x<0\), then \(|x|=−x>0,\) and if \(x>0\), then \(|x|=x>0.\) However, for \(x=0,\) \(|x|=0.\) Therefore, it is more accurate to say that for all nonzero inputs, the output is positive, but if \(x=0\), the output \(|x|=0\). We conclude that the range of the absolute value function is \(\{y\,|\,y≥0\}.\) In Figure \(\PageIndex{13}\), we see that the absolute value function is symmetric about the \(y\)-axis and is therefore an even function.

Example \(\PageIndex{11}\): Working with the Absolute Value Function

Find the domain and range of the function \(f(x)=2|x−3|+4\).

Since the absolute value function is defined for all real numbers, the domain of this function is \((−∞,∞)\). Since \(|x−3|≥0\) for all \(x\), the function \(f(x)=2|x−3|+4≥4\). Therefore, the range is, at most, the set \(\{y\,|\,y≥4\}.\) To see that the range is, in fact, this whole set, we need to show that for \(y≥4\) there exists a real number \(x\) such that

\(2|x−3|+4=y\)

A real number \(x\) satisfies this equation as long as

\(|x−3|=\frac{1}{2}(y−4)\)

Since \(y≥4\), we know \(y−4≥0\), and thus the right-hand side of the equation is nonnegative, so it is possible that there is a solution. Furthermore,

\(|x−3|=\begin{cases} −(x−3), & \text{if } x<3\\x−3, & \text{if } x≥3\end{cases}\)

Therefore, we see there are two solutions:

\(x=±\frac{1}{2}(y−4)+3\).

The range of this function is \(\{y\,|\,y≥4\}.\)

Exercise \(\PageIndex{11}\): Domain and Range

For the function \(f(x)=|x+2|−4\), find the domain and range.

\(|x+2|≥0\) for all real numbers \(x\).

Domain = \((−∞,∞)\), range = \(\{y\,|\,y≥−4\}.\)

Key Concepts

• A function is a mapping from a set of inputs to a set of outputs with exactly one output for each input.
• If no domain is stated for a function \(y=f(x),\) the domain is considered to be the set of all real numbers \(x\) for which the function is defined.
• When sketching the graph of a function \(f,\) each vertical line may intersect the graph, at most, once.
• A function may have any number of zeros, but it has, at most, one \(y\)-intercept.
• To define the composition \(g∘f\), the range of \(f\) must be contained in the domain of \(g\).
• Even functions are symmetric about the \(y\)-axis whereas odd functions are symmetric about the origin.

Key Equations

• Composition of two functions

\((g∘f)(x)=g\big(f(x)\big)\)

• Absolute value function

\(f(x)=\begin{cases}−x, & \text{if } x<0\\x, & \text{if } x≥0\end{cases}\)