overview of the literature review

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Writing a Literature Review

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A literature review is a document or section of a document that collects key sources on a topic and discusses those sources in conversation with each other (also called synthesis ). The lit review is an important genre in many disciplines, not just literature (i.e., the study of works of literature such as novels and plays). When we say “literature review” or refer to “the literature,” we are talking about the research ( scholarship ) in a given field. You will often see the terms “the research,” “the scholarship,” and “the literature” used mostly interchangeably.

Where, when, and why would I write a lit review?

There are a number of different situations where you might write a literature review, each with slightly different expectations; different disciplines, too, have field-specific expectations for what a literature review is and does. For instance, in the humanities, authors might include more overt argumentation and interpretation of source material in their literature reviews, whereas in the sciences, authors are more likely to report study designs and results in their literature reviews; these differences reflect these disciplines’ purposes and conventions in scholarship. You should always look at examples from your own discipline and talk to professors or mentors in your field to be sure you understand your discipline’s conventions, for literature reviews as well as for any other genre.

A literature review can be a part of a research paper or scholarly article, usually falling after the introduction and before the research methods sections. In these cases, the lit review just needs to cover scholarship that is important to the issue you are writing about; sometimes it will also cover key sources that informed your research methodology.

Lit reviews can also be standalone pieces, either as assignments in a class or as publications. In a class, a lit review may be assigned to help students familiarize themselves with a topic and with scholarship in their field, get an idea of the other researchers working on the topic they’re interested in, find gaps in existing research in order to propose new projects, and/or develop a theoretical framework and methodology for later research. As a publication, a lit review usually is meant to help make other scholars’ lives easier by collecting and summarizing, synthesizing, and analyzing existing research on a topic. This can be especially helpful for students or scholars getting into a new research area, or for directing an entire community of scholars toward questions that have not yet been answered.

What are the parts of a lit review?

Most lit reviews use a basic introduction-body-conclusion structure; if your lit review is part of a larger paper, the introduction and conclusion pieces may be just a few sentences while you focus most of your attention on the body. If your lit review is a standalone piece, the introduction and conclusion take up more space and give you a place to discuss your goals, research methods, and conclusions separately from where you discuss the literature itself.

Introduction:

• An introductory paragraph that explains what your working topic and thesis is
• A forecast of key topics or texts that will appear in the review
• Potentially, a description of how you found sources and how you analyzed them for inclusion and discussion in the review (more often found in published, standalone literature reviews than in lit review sections in an article or research paper)
• 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 sentence to draw connections, comparisons, and contrasts.

Conclusion:

• Summarize the key findings you have taken from the literature and emphasize their significance
• Connect it back to your primary research question

How should I organize my lit review?

Lit reviews can take many different organizational patterns depending on what you are trying to accomplish with the review. Here are some examples:

• Chronological : The simplest approach is to trace the development of the topic over time, which helps familiarize the audience with the topic (for instance if you are introducing something that is not commonly known in your field). If you choose this strategy, be careful to avoid simply listing and summarizing sources in order. Try to analyze the patterns, turning points, and key debates that have shaped the direction of the field. Give your interpretation of how and why certain developments occurred (as mentioned previously, this may not be appropriate in your discipline — check with a teacher or mentor if you’re unsure).
• Thematic : If you have found some recurring central themes that you will continue working with throughout your piece, you can organize your literature review into subsections that address different aspects of the topic. For example, if you are reviewing literature about women and religion, key themes can include the role of women in churches and the religious attitude towards women.
• Qualitative versus quantitative research
• Empirical versus theoretical scholarship
• Divide the research by sociological, historical, or cultural sources
• Theoretical : In many humanities articles, the literature review is the foundation for the theoretical framework. You can use it to discuss various theories, models, and definitions of key concepts. You can argue for the relevance of a specific theoretical approach or combine various theorical concepts to create a framework for your research.

What are some strategies or tips I can use while writing my lit review?

Any lit review is only as good as the research it discusses; make sure your sources are well-chosen and your research is thorough. Don’t be afraid to do more research if you discover a new thread as you’re writing. More info on the research process is available in our "Conducting Research" resources .

As you’re doing your research, create an annotated bibliography ( see our page on the this type of document ). Much of the information used in an annotated bibliography can be used also in a literature review, so you’ll be not only partially drafting your lit review as you research, but also developing your sense of the larger conversation going on among scholars, professionals, and any other stakeholders in your topic.

Usually you will need to synthesize research rather than just summarizing it. This means drawing connections between sources to create a picture of the scholarly conversation on a topic over time. Many student writers struggle to synthesize because they feel they don’t have anything to add to the scholars they are citing; here are some strategies to help you:

• It often helps to remember that the point of these kinds of syntheses is to show your readers how you understand your research, to help them read the rest of your paper.
• Writing teachers often say synthesis is like hosting a dinner party: imagine all your sources are together in a room, discussing your topic. What are they saying to each other?
• Look at the in-text citations in each paragraph. Are you citing just one source for each paragraph? This usually indicates summary only. When you have multiple sources cited in a paragraph, you are more likely to be synthesizing them (not always, but often
• Read more about synthesis here.

The most interesting literature reviews are often written as arguments (again, as mentioned at the beginning of the page, this is discipline-specific and doesn’t work for all situations). Often, the literature review is where you can establish your research as filling a particular gap or as relevant in a particular way. You have some chance to do this in your introduction in an article, but the literature review section gives a more extended opportunity to establish the conversation in the way you would like your readers to see it. You can choose the intellectual lineage you would like to be part of and whose definitions matter most to your thinking (mostly humanities-specific, but this goes for sciences as well). In addressing these points, you argue for your place in the conversation, which tends to make the lit review more compelling than a simple reporting of other sources.

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• What is a Literature Review? | Guide, Template, & Examples

What is a Literature Review? | Guide, Template, & Examples

Published on 22 February 2022 by Shona McCombes . Revised on 7 June 2022.

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.

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 summarise sources – it analyses, synthesises, and critically evaluates to give a clear picture of the state of knowledge on the subject.

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Table of contents

Why write 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, frequently asked questions about literature reviews, introduction.

• Quick Run-through
• Step 1 & 2

When you write a dissertation or thesis, you will 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 scholarly context
• Develop a theoretical framework and methodology for your research
• Position yourself in relation to other researchers and theorists
• Show how your dissertation addresses a gap or contributes to a debate

You might also have to write a literature review as a stand-alone assignment. In this case, the purpose is to evaluate the current state of research and demonstrate your knowledge of scholarly debates around a topic.

The content will look slightly different in each case, but the process of conducting a literature review follows the same steps. We’ve written a step-by-step guide that you can follow below.

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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 objectives and questions .

If you are writing a literature review as a stand-alone assignment, you will have to choose a focus and develop a central question to direct your search. Unlike a dissertation research question, this question has to be answerable without collecting original data. You should be able to answer it based only on a review of existing publications.

Make a list of keywords

Start by creating a list of keywords related to your research topic. 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 if 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 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 use boolean operators to help narrow down your search:

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.

To identify the most important publications on your topic, take note of recurring citations. If the same authors, books or articles keep appearing in your reading, make sure to seek them out.

You probably won’t be able to read absolutely everything that has been written on the topic – you’ll have to evaluate which sources are most relevant to your questions.

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?
• How does the publication contribute to your understanding of the topic? What are its key insights and arguments?
• 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 find out how many times an article has been cited on Google Scholar – a high citation count means the article has been influential in the field, and should certainly be included in your literature review.

The scope of your review will depend on your topic and discipline: in the sciences you usually only review recent literature, but in the humanities you might take a long historical perspective (for example, to trace how a concept has changed in meaning over time).

Remember that you can use our template to summarise and evaluate sources you’re thinking about using!

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’s important to keep track of your sources with references to avoid plagiarism . It can be helpful to make an annotated bibliography, where you compile full reference 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.

You can use our free APA Reference Generator for quick, correct, consistent citations.

Prevent plagiarism, run a free check.

To begin organising your literature review’s argument and structure, you need to 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 organising the body of a literature review. You should have a rough idea of your strategy before you start writing.

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 summarising sources in order.

Try to analyse 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 organise 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.

If you are writing the literature review as part of your dissertation or thesis, reiterate your central problem or research question and give a brief summary of the scholarly context. You can emphasise the timeliness of the topic (“many recent studies have focused on the problem of x”) or highlight a gap in the literature (“while there has been much research on x, few researchers have taken y into consideration”).

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, make sure to follow these tips:

• Summarise and synthesise: give an overview of the main points of each source and combine them into a coherent whole.
• Analyse and interpret: don’t just paraphrase other researchers – add your own interpretations, 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 transitions and topic sentences to draw connections, comparisons and contrasts.

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

If the literature review is part of your dissertation or thesis, reiterate how your research addresses gaps and contributes new knowledge, or discuss how you have drawn on existing theories and methods to build a framework for your research. This can lead directly into your methodology section.

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 dissertation , thesis, research paper , or proposal .

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

• To familiarise 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  dissertation . After the introduction , it grounds your research in a scholarly field and leads directly to your theoretical framework or methodology .

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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
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Literature Reviews

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What is a literature review?

A literature review discusses published information in a particular subject area. Often part of the introduction to an essay, research report or thesis, the literature review is literally a "re" view or "look again" at what has already been written about the topic, wherein the author analyzes a segment of a published body of knowledge through summary, classification, and comparison of prior research studies, reviews of literature, and theoretical articles. Literature reviews provide the reader with a bibliographic history of the scholarly research in any given field of study. As such,  as new information becomes available, literature reviews grow in length or become focused on one specific aspect of the topic.

A literature review can be just a simple summary of the sources, but usually contains an organizational pattern and combines both summary and synthesis. A summary is a recap of the important information of the source, whereas a synthesis is a re-organization, or a reshuffling, of that information. The literature review might give a new interpretation of old material or combine new with old interpretations. Or it might trace the intellectual progression of the field, including major debates. Depending on the situation, the literature review may evaluate the sources and advise the reader on the most pertinent or relevant.

A literature review is NOT:

• An annotated bibliography – a list of citations to books, articles and documents that includes a brief description and evaluation for each citation. The annotations inform the reader of the relevance, accuracy and quality of the sources cited.
• A literary review – a critical discussion of the merits and weaknesses of a literary work.
• A book review – a critical discussion of the merits and weaknesses of a particular book.
• Teaching Information Literacy Reframed: 50+ Framework-Based Exercises for Creating Information-Literate Learners
• The UNC Writing Center – Literature Reviews
• The UW-Madison Writing Center: The Writer’s Handbook – Academic and Professional Writing – Learn How to Write a Literature Review

What is the difference between a literature review and a research paper?

The focus of a literature review is to summarize and synthesize the arguments and ideas of others without adding new contributions, whereas academic research papers present and develop new arguments that build upon the previously available body of literature.

How do I write a literature review?

There are many resources that offer step-by-step guidance for writing a literature review, and you can find some of them under Other Resources in the menu to the left. Writing the Literature Review: A Practical Guide suggests these steps:

• Chose a review topic and develop a research question
• Locate and organize research sources
• Select, analyze and annotate sources
• Evaluate research articles and other documents
• Structure and organize the literature review
• Develop arguments and supporting claims
• Synthesize and interpret the literature
• Put it all together

What is the purpose of writing a literature review?

Literature reviews serve as a guide to a particular topic: professionals can use literature reviews to keep current on their field; scholars can determine credibility of the writer in his or her field by analyzing the literature review.

As a writer, you will use the literature review to:

• See what has, and what has not, been investigated about your topic
• Identify data sources that other researches have used
• Learn how others in the field have defined and measured key concepts
• Establish context, or background, for the argument explored in the rest of a paper
• Explain what the strengths and weaknesses of that knowledge and ideas might be
• Contribute to the field by moving research forward
• To keep the writer/reader up to date with current developments in a particular field of study
• Develop alternative research projects
• Put your work in perspective
• Demonstrate your understanding and your ability to critically evaluate research in the field
• Provide evidence that may support your own findings
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Literature Reviews

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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.

Meryl Brodsky : Communication and Information Studies

Hannah Chapman Tripp : Biology, Neuroscience

Carolyn Cunningham : Human Development & Family Sciences, Psychology, Sociology

Larayne Dallas : Engineering

Janelle Hedstrom : Special Education, Curriculum & Instruction, Ed Leadership & Policy ​

Susan Macicak : Linguistics

Imelda Vetter : Dell Medical School

For help in other subject areas, please see the guide to library specialists by subject .

Periodically, UT Libraries runs a workshop covering the basics and library support for literature reviews. While we try to offer these once per academic year, we find providing the recording to be helpful to community members who have missed the session. Following is the most recent recording of the workshop, Conducting a Literature Review. To view the recording, a UT login is required.

• October 26, 2022 recording
• Last Updated: Oct 26, 2022 2:49 PM
• URL: https://guides.lib.utexas.edu/literaturereviews

How to Write a Literature Review

What is a literature review.

• What Is the Literature
• Writing the Review

A literature review is much more than an annotated bibliography or a list of separate reviews of articles and books. It is a critical, analytical summary and synthesis of the current knowledge of a topic. Thus it should compare and relate different theories, findings, etc, rather than just summarize them individually. In addition, it should have a particular focus or theme to organize the review. It does not have to be an exhaustive account of everything published on the topic, but it should discuss all the significant academic literature and other relevant sources important for that focus.

This is meant to be a general guide to writing a literature review: ways to structure one, what to include, how it supplements other research. For more specific help on writing a review, and especially for help on finding the literature to review, sign up for a Personal Research Session .

The specific organization of a literature review depends on the type and purpose of the review, as well as on the specific field or topic being reviewed. But in general, it is a relatively brief but thorough exploration of past and current work on a topic. Rather than a chronological listing of previous work, though, literature reviews are usually organized thematically, such as different theoretical approaches, methodologies, or specific issues or concepts involved in the topic. A thematic organization makes it much easier to examine contrasting perspectives, theoretical approaches, methodologies, findings, etc, and to analyze the strengths and weaknesses of, and point out any gaps in, previous research. And this is the heart of what a literature review is about. A literature review may offer new interpretations, theoretical approaches, or other ideas; if it is part of a research proposal or report it should demonstrate the relationship of the proposed or reported research to others' work; but whatever else it does, it must provide a critical overview of the current state of research efforts. 

Literature reviews are common and very important in the sciences and social sciences. They are less common and have a less important role in the humanities, but they do have a place, especially stand-alone reviews.

Types of Literature Reviews

There are different types of literature reviews, and different purposes for writing a review, but the most common are:

• Stand-alone literature review articles . These provide an overview and analysis of the current state of research on a topic or question. The goal is to evaluate and compare previous research on a topic to provide an analysis of what is currently known, and also to reveal controversies, weaknesses, and gaps in current work, thus pointing to directions for future research. You can find examples published in any number of academic journals, but there is a series of Annual Reviews of *Subject* which are specifically devoted to literature review articles. Writing a stand-alone review is often an effective way to get a good handle on a topic and to develop ideas for your own research program. For example, contrasting theoretical approaches or conflicting interpretations of findings can be the basis of your research project: can you find evidence supporting one interpretation against another, or can you propose an alternative interpretation that overcomes their limitations?
• Part of a research proposal . This could be a proposal for a PhD dissertation, a senior thesis, or a class project. It could also be a submission for a grant. The literature review, by pointing out the current issues and questions concerning a topic, is a crucial part of demonstrating how your proposed research will contribute to the field, and thus of convincing your thesis committee to allow you to pursue the topic of your interest or a funding agency to pay for your research efforts.
• Part of a research report . When you finish your research and write your thesis or paper to present your findings, it should include a literature review to provide the context to which your work is a contribution. Your report, in addition to detailing the methods, results, etc. of your research, should show how your work relates to others' work.

A literature review for a research report is often a revision of the review for a research proposal, which can be a revision of a stand-alone review. Each revision should be a fairly extensive revision. With the increased knowledge of and experience in the topic as you proceed, your understanding of the topic will increase. Thus, you will be in a better position to analyze and critique the literature. In addition, your focus will change as you proceed in your research. Some areas of the literature you initially reviewed will be marginal or irrelevant for your eventual research, and you will need to explore other areas more thoroughly. 

Examples of Literature Reviews

See the series of Annual Reviews of *Subject* which are specifically devoted to literature review articles to find many examples of stand-alone literature reviews in the biomedical, physical, and social sciences. 

Research report articles vary in how they are organized, but a common general structure is to have sections such as:

• Abstract - Brief summary of the contents of the article
• Introduction - A explanation of the purpose of the study, a statement of the research question(s) the study intends to address
• Literature review - A critical assessment of the work done so far on this topic, to show how the current study relates to what has already been done
• Methods - How the study was carried out (e.g. instruments or equipment, procedures, methods to gather and analyze data)
• Results - What was found in the course of the study
• Discussion - What do the results mean
• Conclusion - State the conclusions and implications of the results, and discuss how it relates to the work reviewed in the literature review; also, point to directions for further work in the area

Here are some articles that illustrate variations on this theme. There is no need to read the entire articles (unless the contents interest you); just quickly browse through to see the sections, and see how each section is introduced and what is contained in them.

The Determinants of Undergraduate Grade Point Average: The Relative Importance of Family Background, High School Resources, and Peer Group Effects , in The Journal of Human Resources , v. 34 no. 2 (Spring 1999), p. 268-293.

This article has a standard breakdown of sections:

• Introduction
• Literature Review
• Some discussion sections

First Encounters of the Bureaucratic Kind: Early Freshman Experiences with a Campus Bureaucracy , in The Journal of Higher Education , v. 67 no. 6 (Nov-Dec 1996), p. 660-691.

This one does not have a section specifically labeled as a "literature review" or "review of the literature," but the first few sections cite a long list of other sources discussing previous research in the area before the authors present their own study they are reporting.

• Next: What Is the Literature >>
• Last Updated: Jan 11, 2024 9:48 AM
• URL: https://libguides.wesleyan.edu/litreview

Literature Reviews

What is a literature review.

• Literature Review Process

Purpose of a Literature Review

• Choosing a Type of Review
• Developing a Research Question
• Searching the Literature
• Searching Tips
• ChatGPT [beta]
• Documenting your Search
• Using Citation Managers
• Concept Mapping
• Writing the Review
• Further Resources

The Library's Subject Specialists are happy to help with your literature reviews!  Find your Subject Specialist here . 

If you have questions about this guide, contact Librarian  Jamie Niehof ([email protected]).

A literature review is an overview of the available research for a specific scientific topic. Literature reviews summarize existing research to answer a review question, provide context for new research, or identify important gaps in the existing body of literature.

An incredible amount of academic literature is published each year, by estimates over two million articles .

Sorting through and reviewing that literature can be complicated, so this Research Guide provides a structured approach to make the process more manageable.

THIS GUIDE IS AN OVERVIEW OF THE LITERATURE REVIEW PROCESS:

• Getting Started (asking a research question | defining scope)
• Organizing the Literature
• Writing the Literature Review (analyzing | synthesizing)

A  literature search  is a systematic search of the scholarly sources in a particular discipline. A  literature review   is the analysis, critical evaluation and synthesis of the results of that search. During this process you will move from a review  of  the literature to a review  for   your research.   Your synthesis of the literature is your unique contribution to research.

WHO IS THIS RESEARCH GUIDE FOR?

— those new to reviewing the literature

— those that need a refresher or a deeper understanding of writing literature reviews

You may need to do a literature review as a part of a course assignment, a capstone project, a master's thesis, a dissertation, or as part of a journal article. No matter the context, a literature review is an essential part of the research process. 

WHAT IS THE PURPOSE OF A LITERATURE REVIEW?

A literature review is typically performed for a specific reason. Even when assigned as an assignment, the goal of the literature review will be one or more of the following:

• To communicate a project's novelty by identifying a research gap

• An overview of research issues , methodologies or results relevant to field
• To explore the  volume and types of available studies
• To establish familiarity with current research before carrying out a new project
• To resolve conflicts amongst contradictory previous studies

Reviewing the literature helps you understand a research topic and develop your own perspective.

A LITERATURE REVIEW IS NOT :

• An annotated bibliography – which is a list of annotated citations to books, articles and documents that includes a brief description and evaluation for each entry
• A literary review – which is a critical discussion of the merits and weaknesses of a literary work
• A book review – which is a critical discussion of the merits and weaknesses of a particular book
• Next: Choosing a Type of Review >>
• Last Updated: Feb 29, 2024 10:31 AM
• URL: https://guides.lib.umich.edu/litreview

Writing a Literature Review

What is a literature review, purpose of a literature review, structure of a literature review, information to consider in your review: what to write about, further readings, useful tools.

• Engineering Home

The literature review is a critical look at the existing research that is significant to the work that you are carrying out. This overview identifies prominent research trends in addition to assessing the overall strengths and weaknesses of the existing research.

• From Penn State University
• To provide background information about a research topic.
• To establish the importance of a topic.
• To demonstrate familiarity with a topic/problem.
• To “carve out a space” for further work and allow you to position yourself in a scholarly conversation.

Penn State University  

Your review should follow the following structure:

• Write this last
• A summary of your main thesis and the studies you examine in your review
• Introduce your topic
• Outline what you will discuss throughout the review
• Frame the paper with your thesis
• Tell your audience why it is important that you reviewed the literature in your topic area
• Can take different forms depending on your topic
• Break it up into sections if this is helpful (i.e. if you are studying three different methodologies, then you can break your body into three main sections)
• Go through all of the literature in detail, in an organized fashion
• Restate your thesis
• Wrap up your review by drawing everything together and making sure it is clear what conclusions you draw about your topic or field of study based on the research studies you read and analyzed.
• Make sure your references are formatted correctly and all present
• This paper is all about the references! Cite everything that you discuss. For tips on when and how to cite, visit the next page on the drop-down menu under "Writing in the Sciences!"

Adapted from the   UCLA Undergraduate Science Journal

When doing research for your review, here is a list of questions to consider as you read through articles to potentially include:

• What is the  thesis  or  problem being addressed  in this paper? 
• What are the  strengths and limitations  of the study? Is there a better way to answer the research question?
• How does the author approach the study - from a theoretical, experimental, interpretive, or clinical (etc.) standpoint? Did they choose the best approach?
• Is the author using an assumed theoretical framework such as, for example, psychoanalytic or developmental? How does this affect the conclusions they draw? 
• How does the author engage with other literature in the field? Is literature that both contradicts and supports his/her findings mentioned? 
• Did the researchers choose appropriate methods of experimentation and data analysis for the research question? 
• Do you think that the conclusions they draw based upon the data they present are valid and reasonable? Or are there gaps in the logic or assumptions being made?
• Does this particular research study contribute to the knowledge base of the field around which you're centering your review? Is it worth including in your discussion, and does it fit your main thesis?
• The Literature Review: A Few Tips on Conducting It Written by Dena Taylor, Health Sciences Writing Centre, University of Toronto
• Literature Reviews Created by The Writing Center at the University of North Carolina, Chapel Hill.
• Literature Review Template
• Literature Reviews Penn State University Libraries
• Writing and Rhetoric Writing and Rhetoric: Writing & Citing Library Guide by Laura Barrett
• Dartmouth Citation Linker Find out if the library has access to the full-text of a citation. Can use just the DOI or PMID.
• LibKey Nomad Browser plugin Single click access to library content from publisher websites, PubMed, Wikipedia, and more.
• ZoteroBib To create a citation in ZoteroBib, simply input the URL of the item in the search box. If the URL isn’t generating the citation you need, or if the item is in print, you can also use the DOI, ISBN, PubMed ID, arXive ID, or title of the item for Zotero to look up the bibliographic data.
• Next: Engineering Home >>
• Last Updated: Aug 29, 2022 4:54 PM
• URL: https://researchguides.dartmouth.edu/writing-a-literature-review

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• CAREER FEATURE
• 04 December 2020
• Correction 09 December 2020

How to write a superb literature review

Andy Tay is a freelance writer based in Singapore.

You can also search for this author in PubMed   Google Scholar

Literature reviews are important resources for scientists. They provide historical context for a field while offering opinions on its future trajectory. Creating them can provide inspiration for one’s own research, as well as some practice in writing. But few scientists are trained in how to write a review — or in what constitutes an excellent one. Even picking the appropriate software to use can be an involved decision (see ‘Tools and techniques’). So Nature asked editors and working scientists with well-cited reviews for their tips.

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doi: https://doi.org/10.1038/d41586-020-03422-x

Interviews have been edited for length and clarity.

Updates & Corrections

Correction 09 December 2020 : An earlier version of the tables in this article included some incorrect details about the programs Zotero, Endnote and Manubot. These have now been corrected.

Hsing, I.-M., Xu, Y. & Zhao, W. Electroanalysis 19 , 755–768 (2007).

Article   Google Scholar  

Ledesma, H. A. et al. Nature Nanotechnol. 14 , 645–657 (2019).

Article   PubMed   Google Scholar  

Brahlek, M., Koirala, N., Bansal, N. & Oh, S. Solid State Commun. 215–216 , 54–62 (2015).

Choi, Y. & Lee, S. Y. Nature Rev. Chem . https://doi.org/10.1038/s41570-020-00221-w (2020).

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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: 
• 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  

• 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. 
• 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. 
• 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. 
• 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. 
• 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. 
• 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. 

How to write a good literature review

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. 

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. 

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 literature review is an ongoing process, and it may be necessary to revisit and update it as your research progresses. 

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 . 

Paperpal is an AI writing assistant that help academics write better, faster with real-time suggestions for in-depth language and grammar correction. Trained on millions of research manuscripts enhanced by professional academic editors, Paperpal delivers human precision at machine speed.  

Try it for free or upgrade to  Paperpal Prime , which unlocks unlimited access to premium features like academic translation, paraphrasing, contextual synonyms, consistency checks and more. It’s like always having a professional academic editor by your side! Go beyond limitations and experience the future of academic writing.  Get Paperpal Prime now at just US$19 a month!

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• Empirical Research: A Comprehensive Guide for Academics 
• How to Write a Scientific Paper in 10 Steps 
• Life Sciences Papers: 9 Tips for Authors Writing in Biological Sciences
• What is an Argumentative Essay? How to Write It (With Examples)

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Literature Reviews

• Getting started

What is a literature review?

Why conduct a literature review, stages of a literature review, lit reviews: an overview (video), check out these books.

• Types of reviews
• 1. Define your research question
• 2. Plan your search
• 3. Search the literature
• 4. Organize your results
• 5. Synthesize your findings
• 6. Write the review
• Artificial intelligence (AI) tools
• Thompson Writing Studio This link opens in a new window
• Need to write a systematic review? This link opens in a new window

Contact a Librarian

Ask a Librarian

Definition: A literature review is a systematic examination and synthesis of existing scholarly research on a specific topic or subject.

Purpose: It serves to provide a comprehensive overview of the current state of knowledge within a particular field.

Analysis: Involves critically evaluating and summarizing key findings, methodologies, and debates found in academic literature.

Identifying Gaps: Aims to pinpoint areas where there is a lack of research or unresolved questions, highlighting opportunities for further investigation.

Contextualization: Enables researchers to understand how their work fits into the broader academic conversation and contributes to the existing body of knowledge.

tl;dr  A literature review critically examines and synthesizes existing scholarly research and publications on a specific topic to provide a comprehensive understanding of the current state of knowledge in the field.

What is a literature review NOT?

❌ An annotated bibliography

❌ Original research

❌ A summary

❌ Something to be conducted at the end of your research

❌ An opinion piece

❌ A chronological compilation of studies

The reason for conducting a literature review is to:

Literature Reviews: An Overview for Graduate Students

While this 9-minute video from NCSU is geared toward graduate students, it is useful for anyone conducting a literature review.

Writing the literature review: A practical guide

Available 3rd floor of Perkins

Writing literature reviews: A guide for students of the social and behavioral sciences

Available online!

So, you have to write a literature review: A guided workbook for engineers

Telling a research story: Writing a literature review

The literature review: Six steps to success

Systematic approaches to a successful literature review

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Writing Literature Reviews: What is a "Literature Review"?

• What is a "Literature Review"?
• 1. Brainstorm
• 3. Refine Search and Topic
• 4. Structure Your Lit Review
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Literature reviews:

• provide a summary of the published academic work on a topic
• help "make the case" for why someone is writing their paper or conducting their research
• can be the "background" section of a larger paper or it can be the focus of an entire paper

Goals of a Literature Review

• including the major theories, issues, works, and debates in the field
• synthesize all this information into an organized summary
• critique current knowledge of a topic
• identify aspects of the topic that need further investigation

Plagiarism and Citation

Citation is when you give credit to someone else's ideas, words, creative works, or contributions in your own paper.

Reasons to cite:

• Give credit the author(s) of the works that you used to write your paper.
• Avoid plagiarism (which means you are claiming someone else's work as your own. This will get you in big trouble. See the Purdue Online Writing Lab for more information.)
• Show that you know your topic well and have read and thought about what others have already said.
• Show your readers where to find the original sources of the information you present so they can read them fully.

When to cite? What to cite?

• Cite other people's words, ideas and other intellectual property that you use in your papers or that influence your ideas, including things such as books, articles, reports, data/statistics, speeches, academic articles, works of art, songs.
• Cite direct quotes, facts or statistics AND when you summarize or paraphrase others' ideas.

Helpful Sites on Literature Reviews

Much of the information in this guide and more information can be found on the websites listed on the  Helpful Sites tab .

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Organizing Your Social Sciences Research Paper

• 5. The Literature Review
• Purpose of Guide
• Design Flaws to Avoid
• Independent and Dependent Variables
• Glossary of Research Terms
• Reading Research Effectively
• Narrowing a Topic Idea
• Broadening a Topic Idea
• Extending the Timeliness of a Topic Idea
• Academic Writing Style
• Applying Critical Thinking
• Choosing a Title
• Making an Outline
• Paragraph Development
• Research Process Video Series
• Executive Summary
• The C.A.R.S. Model
• Background Information
• The Research Problem/Question
• Theoretical Framework
• Citation Tracking
• Content Alert Services
• Evaluating Sources
• Primary Sources
• Secondary Sources
• Tiertiary Sources
• Scholarly vs. Popular Publications
• Qualitative Methods
• Quantitative Methods
• Insiderness
• Using Non-Textual Elements
• Limitations of the Study
• Common Grammar Mistakes
• Writing Concisely
• Avoiding Plagiarism
• Footnotes or Endnotes?
• Further Readings
• Generative AI and Writing
• USC Libraries Tutorials and Other Guides
• Bibliography

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

• Planning the Review
• The Research Question
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• 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 Collection 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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Literature Reviews: Overview

What is a literature review.

A literature review synthesizes scholarly literature on a topic by evaluating a selection of sources.

It describes common themes, but must also demonstrate the author's understanding of the literature through critical analysis, as well as identify gaps and/or controversies in the research.

The Basics of a Literature Review. (2014). Teaching and Learning Center University of Washington Tacoma. Retrieved from  https://www.tacoma.uw.edu/sites/default/files/2021-05/basics-of-lit-review1.pdf

Additional Assistance

Have more questions about your literature review?

• Contact a Librarian for help locating research
• Contact the Teaching and Learning Center f or help writing, revising and formatting

What is the Purpose of a Literature Review?

To help define the focus of your research topic.

To identify research already conducted in your field of interest, find gaps in existing scholarship, and avoid repetition of previous research.

To become familiar with significant earlier research and with current progress and/or controversy in your field of interest.

To  diagnose  the strengths and weaknesses in the works pertaining to your field of interest.

To assess the experts, theoretical approaches, methodologies, results, conclusions, and possible opportunities for future research in your field of interest.

Literature Review vs. Annotated Bibliography

Literature reviews and annotated bibliographies are highly useful for constructing your research project. Both provide an examination of relevant scholarly work pertaining to a specific topic, but there are also significant differences between them.

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Organizing and Creating Information

• Citation and Attribution

What Is a Literature Review?

Review the literature, write the literature review, further reading, learning objectives, attribution.

This guide is designed to:

• Identify the sections and purpose of a literature review in academic writing
• Review practical strategies and organizational methods for preparing a literature review

A literature review is a summary and synthesis of scholarly research on a specific topic. It should answer questions such as:

• What research has been done on the topic?
• Who are the key researchers and experts in the field?
• What are the common theories and methodologies?
• Are there challenges, controversies, and contradictions?
• Are there gaps in the research that your approach addresses?

The process of reviewing existing research allows you to fine-tune your research question and contextualize your own work. Preparing a literature review is a cyclical process. You may find that the research question you begin with evolves as you learn more about the topic.

Once you have defined your research question , focus on learning what other scholars have written on the topic.

In order to  do a thorough search of the literature  on the topic, define the basic criteria:

• Databases and journals: Look at the  subject guide  related to your topic for recommended databases. Review the  tutorial on finding articles  for tips. 
• Books: Search BruKnow, the Library's catalog. Steps to searching ebooks are covered in the  Finding Ebooks tutorial .
• What time period should it cover? Is currency important?
• Do I know of primary and secondary sources that I can use as a way to find other information?
• What should I be aware of when looking at popular, trade, and scholarly resources ? 

One strategy is to review bibliographies for sources that relate to your interest. For more on this technique, look at the tutorial on finding articles when you have a citation .

Tip: Use a Synthesis Matrix

As you read sources, themes will emerge that will help you to organize the review. You can use a simple Synthesis Matrix to track your notes as you read. From this work, a concept map emerges that provides an overview of the literature and ways in which it connects. Working with Zotero to capture the citations, you build the structure for writing your literature review.

How do I know when I am done?

A key indicator for knowing when you are done is running into the same articles and materials. With no new information being uncovered, you are likely exhausting your current search and should modify search terms or search different catalogs or databases. It is also possible that you have reached a point when you can start writing the literature review.

Tip: Manage Your Citations

These citation management tools also create citations, footnotes, and bibliographies with just a few clicks:

Zotero Tutorial

Endnote Tutorial

Your literature review should be focused on the topic defined in your research question. It should be written in a logical, structured way and maintain an objective perspective and use a formal voice.

Review the Summary Table you created for themes and connecting ideas. Use the following guidelines to prepare an outline of the main points you want to make. 

• Synthesize previous research on the topic.
• Aim to include both summary and synthesis.
• Include literature that supports your research question as well as that which offers a different perspective.
• Avoid relying on one author or publication too heavily.
• Select an organizational structure, such as chronological, methodological, and thematic.

The three elements of a literature review are introduction, body, and conclusion.

Introduction

• Define the topic of the literature review, including any terminology.
• Introduce the central theme and organization of the literature review.
• Summarize the state of research on the topic.
• Frame the literature review with your research question.
• Focus on ways to have the body of literature tell its own story. Do not add your own interpretations at this point.
• Look for patterns and find ways to tie the pieces together.
• Summarize instead of quote.
• Weave the points together rather than list summaries of each source.
• Include the most important sources, not everything you have read.
• Summarize the review of the literature.
• Identify areas of further research on the topic.
• Connect the review with your research.
• DeCarlo, M. (2018). 4.1 What is a literature review? In Scientific Inquiry in Social Work. Open Social Work Education. https://scientificinquiryinsocialwork.pressbooks.com/chapter/4-1-what-is-a-literature-review/
• Literature Reviews (n.d.) https://writingcenter.unc.edu/tips-and-tools/literature-reviews/ Accessed Nov. 10, 2021

This guide was designed to: 

• Identify the sections and purpose of a literature review in academic writing 
• Review practical strategies and organizational methods for preparing a literature review​

Content on this page adapted from: 

Frederiksen, L. and Phelps, S. (2017).   Literature Reviews for Education and Nursing Graduate Students.  Licensed CC BY 4.0

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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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What is a literature review?

A literature review is an integrated analysis -- not just a summary-- of scholarly writings and other relevant evidence related directly to your research question.  That is, it represents a synthesis of the evidence that provides background information on your topic and shows a association between the evidence and your research question.

A literature review may be a stand alone work or the introduction to a larger research paper, depending on the assignment.  Rely heavily on the guidelines your instructor has given you.

Why is it important?

A literature review is important because it:

• Explains the background of research on a topic.
• Demonstrates why a topic is significant to a subject area.
• Discovers relationships between research studies/ideas.
• Identifies major themes, concepts, and researchers on a topic.
• Identifies critical gaps and points of disagreement.
• Discusses further research questions that logically come out of the previous studies.

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1. Choose a topic. Define your research question.

Your literature review should be guided by your central research question.  The literature represents background and research developments related to a specific research question, interpreted and analyzed by you in a synthesized way.

• Make sure your research question is not too broad or too narrow.  Is it manageable?
• Begin writing down terms that are related to your question. These will be useful for searches later.
• If you have the opportunity, discuss your topic with your professor and your class mates.

2. Decide on the scope of your review

How many studies do you need to look at? How comprehensive should it be? How many years should it cover? 

• This may depend on your assignment.  How many sources does the assignment require?

3. Select the databases you will use to conduct your searches.

Make a list of the databases you will search. 

Where to find databases:

• use the tabs on this guide
• Find other databases in the Nursing Information Resources web page
• More on the Medical Library web page
• ... and more on the Yale University Library web page

4. Conduct your searches to find the evidence. Keep track of your searches.

• Use the key words in your question, as well as synonyms for those words, as terms in your search. Use the database tutorials for help.
• Save the searches in the databases. This saves time when you want to redo, or modify, the searches. It is also helpful to use as a guide is the searches are not finding any useful results.
• Review the abstracts of research studies carefully. This will save you time.
• Use the bibliographies and references of research studies you find to locate others.
• Check with your professor, or a subject expert in the field, if you are missing any key works in the field.
• Ask your librarian for help at any time.
• Use a citation manager, such as EndNote as the repository for your citations. See the EndNote tutorials for help.

Review the literature

Some questions to help you analyze the research:

• What was the research question of the study you are reviewing? What were the authors trying to discover?
• Was the research funded by a source that could influence the findings?
• What were the research methodologies? Analyze its literature review, the samples and variables used, the results, and the conclusions.
• Does the research seem to be complete? Could it have been conducted more soundly? What further questions does it raise?
• If there are conflicting studies, why do you think that is?
• How are the authors viewed in the field? Has this study been cited? If so, how has it been analyzed?

Tips: 

• Review the abstracts carefully.  
• Keep careful notes so that you may track your thought processes during the research process.
• Create a matrix of the studies for easy analysis, and synthesis, across all of the studies.
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Literature review.

• What is a Literature Review?
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• 2. Set the Topic in Context
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• 8. Write the Literature Review

A literature review is a comprehensive summary of previous research on a topic. The literature review surveys scholarly articles, books, and other sources relevant to a particular area of research.  The review should enumerate, describe, summarize, objectively evaluate and clarify this previous research.  It should give a theoretical base for the research and help you (the author) determine the nature of your research.  The literature review acknowledges the work of previous researchers, and in so doing, assures the reader that your work has been well conceived.  It is assumed that by mentioning a previous work in the field of study, that the author has read, evaluated, and assimiliated that work into the work at hand.

A literature review creates a "landscape" for the reader, giving her or him a full understanding of the developments in the field.  This landscape informs the reader that the author has indeed assimilated all (or the vast majority of) previous, significant works in the field into her or his research. 

 "In writing the literature review, the purpose is to convey to the reader what knowledge and ideas have been established on a topic, and what their strengths and weaknesses are. The literature review must be defined by a guiding concept (eg. 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.( http://www.writing.utoronto.ca/advice/specific-types-of-writing/literature-review )

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The Literature Review Step by Step: Overview

Searching tips.

• Use Keywords
• Brainstorm Synonyms
• Use Search Tools
• Evaluating Resources using ESCAPE
• Peer-Review: What is it and How to Tell

Example Topic:  How do stereotypes affect female politicians during elections?

Keywords:  stereotypes, female politicians, elections

Most words have synonyms that mean the same, or very similar, things. For each keyword in your topic, try to come up with at least one synonym. Not all keywords will have synonyms, but many do!

Example: 

Keep an Eye Out

Sometimes scholars use terms that you might not be familiar with, or which might mean something very specific within the discipline. While searching, look for unfamiliar terms or words that show up a lot. Try searching for those and see if you find more relevant sources.

Most library databases have search tools built in. Try some of these:

• Date Range:  Limit your search to sources published between specific years.
• Peer Reviewed:  Limit your search to scholarly journal articles.
• Full Text:  Make sure all of the results are available to read in full.

Or look for an "advanced search" page to find these tools - and more!

You can evaluate any source using the ESCAPE plan.

Find out more about ESCAPE in our Evaluating Information Tutorial .

• Peer Review Process (PDF)
• Peer Review Clues (PDF)

Advanced Search Tips

• Too Many Results?
• Too Few Results?
• Wrong Results?

Use the operator AND to find only sources that mention both keywords.

This search will bring back fewer results than searching either keyword on its own.

Use the OR operator to expand your search with additional keywords.

This will find sources that include either word, so you'll see more results than by searching for just one keyword.

Use the “QUOTES” strategy to search for several words in a phrase.

This will bring back results that only use that exact phrase.

Search the Library Databases

Credo Reference provides full-text online versions of over 3,500 published reference works from more than 100 publishers in a variety of major subjects.

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Literature review vs research articles: how are they different.

Unlock the secrets of academic writing with our guide to the key differences between a literature review and a research paper! 📚 Dive into the world of scholarly exploration as we break down how a literature review illuminates existing knowledge, identifies gaps, and sets the stage for further research. 🌐 Then, gear up for the adventure of crafting a research paper, where you become the explorer, presenting your unique insights and discoveries through independent research. 🚀 Join us on this academic journey and discover the art of synthesizing existing wisdom and creating your own scholarly masterpiece! 🎓✨

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• Volume 33, Issue 5
• Equitable and accessible informed healthcare consent process for people with intellectual disability: a systematic literature review
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• http://orcid.org/0000-0002-8498-7329 Manjekah Dunn 1 , 2 ,
• Iva Strnadová 3 , 4 , 5 ,
• Jackie Leach Scully 4 ,
• Jennifer Hansen 3 ,
• Julie Loblinzk 3 , 5 ,
• Skie Sarfaraz 5 ,
• Chloe Molnar 1 ,
• Elizabeth Emma Palmer 1 , 2
• 1 Faculty of Medicine & Health , University of New South Wales , Sydney , New South Wales , Australia
• 2 The Sydney Children's Hospitals Network , Sydney , New South Wales , Australia
• 3 School of Education , University of New South Wales , Sydney , New South Wales , Australia
• 4 Disability Innovation Institute , University of New South Wales , Sydney , New South Wales , Australia
• 5 Self Advocacy Sydney , Sydney , New South Wales , Australia
• Correspondence to Dr Manjekah Dunn, Paediatrics & Child Health, University of New South Wales Medicine & Health, Sydney, New South Wales, Australia; manjekah.dunn{at}unsw.edu.au

Objective To identify factors acting as barriers or enablers to the process of healthcare consent for people with intellectual disability and to understand how to make this process equitable and accessible.

Data sources Databases: Embase, MEDLINE, PsychINFO, PubMed, SCOPUS, Web of Science and CINAHL. Additional articles were obtained from an ancestral search and hand-searching three journals.

Eligibility criteria Peer-reviewed original research about the consent process for healthcare interventions, published after 1990, involving adult participants with intellectual disability.

Synthesis of results Inductive thematic analysis was used to identify factors affecting informed consent. The findings were reviewed by co-researchers with intellectual disability to ensure they reflected lived experiences, and an easy read summary was created.

Results Twenty-three studies were included (1999 to 2020), with a mix of qualitative (n=14), quantitative (n=6) and mixed-methods (n=3) studies. Participant numbers ranged from 9 to 604 people (median 21) and included people with intellectual disability, health professionals, carers and support people, and others working with people with intellectual disability. Six themes were identified: (1) health professionals’ attitudes and lack of education, (2) inadequate accessible health information, (3) involvement of support people, (4) systemic constraints, (5) person-centred informed consent and (6) effective communication between health professionals and patients. Themes were barriers (themes 1, 2 and 4), enablers (themes 5 and 6) or both (theme 3).

Conclusions Multiple reasons contribute to poor consent practices for people with intellectual disability in current health systems. Recommendations include addressing health professionals’ attitudes and lack of education in informed consent with clinician training, the co-production of accessible information resources and further inclusive research into informed consent for people with intellectual disability.

PROSPERO registration CRD42021290548.

• Decision making
• Healthcare quality improvement
• Patient-centred care
• Quality improvement
• Standards of care

Data availability statement

Data are available upon reasonable request. Additional data and materials such as data collection forms, data extraction and analysis templates and QualSyst assessment data can be obtained by contacting the corresponding author.

This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/ .

https://doi.org/10.1136/bmjqs-2023-016113

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What is already known on this topic

People with intellectual disability are frequently excluded from decision-making processes and not provided equal opportunity for informed consent, despite protections outlined in the United Nations Convention on the Rights of Persons with Disabilities.

People with intellectual disability have the capacity and desire to make informed medical decisions, which can improve their well-being, health satisfaction and health outcomes.

What this review study adds

Health professionals lack adequate training in valid informed consent and making reasonable adjustments for people with intellectual disability, and continue to perpetuate assumptions of incapacity.

Health information provided to people with intellectual disability is often inaccessible and insufficient for them to make informed decisions about healthcare.

The role of support people, systemic constraints, a person-centred approach and ineffective healthcare communication also affect informed consent.

How this review might affect research, practice or policy

Health professionals need additional training on how to provide a valid informed consent process for people with intellectual disability, specifically in using accessible health information, making reasonable adjustments (e.g., longer/multiple appointments, options of a support person attending or not, using plain English), involving the individual in discussions, and communicating effectively with them.

Inclusive research is needed to hear the voices and opinions of people with intellectual disability about healthcare decision-making and about informed consent practices in specific healthcare settings.

Introduction

Approximately 1% of the world’s population have intellectual disability. 1 Intellectual disability is medically defined as a group of neurodevelopmental conditions beginning in childhood, with below average cognitive functioning and adaptive behaviour, including limitations in conceptual, social and practical skills. 2 People with intellectual disability prefer an alternative strength-based definition, reflected in the comment by Robert Strike OAM (Order of Australia Medal): ‘We can learn if the way of teaching matches how the person learns’, 3 reinforcing the importance of providing information tailored to the needs of a person with intellectual disability. A diagnosis of intellectual disability is associated with significant disparities in health outcomes. 4–7 Person-centred decision-making and better communication have been shown to improve patient satisfaction, 8 9 the physician–patient relationship 10 and overall health outcomes 11 for the wider population. Ensuring people with intellectual disability experience informed decision-making and accessible healthcare can help address the ongoing health disparities and facilitate equal access to healthcare.

Bodily autonomy is an individual’s power and agency to make decisions about their own body. 12 Informed consent for healthcare enables a person to practice bodily autonomy and is protected, for example, by the National Safety and Quality Health Service Standards (Australia), 13 Mental Capacity Act (UK) 14 and the Joint Commission Standards (USA). 15 In this article, we define informed consent according to three requirements: (1) the person is provided with information they understand, (2) the decision is free of coercion and (3) the person must have capacity. 16 For informed consent to be valid, this process must be suited to the individual’s needs so that they can understand and communicate effectively. Capacity is the ability to give informed consent for a medical intervention, 17 18 and the Mental Capacity Act outlines that ‘a person must be assumed to have capacity unless it is established that he lacks capacity’ and that incapacity can only be established if ‘all practicable steps’ to support capacity have been attempted without success. 14 These assumptions of capacity are also decision-specific, meaning an individual’s ability to consent can change depending on the situation, the choice itself and other factors. 17

Systemic issues with healthcare delivery systems have resulted in access barriers for people with intellectual disability, 19 despite the disability discrimination legislation in many countries who are signatories to the United Nations (UN) Convention on the Rights of Persons with Disabilities. 20 Patients with intellectual disability are not provided the reasonable adjustments that would enable them to give informed consent for medical procedures or interventions, 21 22 despite evidence that many people with intellectual disability have both the capacity and the desire to make their own healthcare decisions. 21 23

To support people with intellectual disability to make independent health decisions, an equitable and accessible informed consent process is needed. 24 However, current health systems have consistently failed to provide this. 21 25 To address this gap, we must first understand the factors that contribute to inequitable and inaccessible consent. To the best of our knowledge, the only current review of informed consent for people with intellectual disability is an integrative review by Goldsmith et al . 26 Many of the included articles focused on assessment of capacity 27–29 and research consent. 30–32 The review’s conclusion supported the functional approach to assess capacity, with minimal focus on how the informed consent processes can be improved. More recently, there has been a move towards ensuring that the consent process is accessible for all individuals, including elderly patients 33 and people with aphasia. 34 However, there remains a paucity of literature about the informed consent process for people with intellectual disability, with no systematic reviews summarising the factors influencing the healthcare consent process for people with intellectual disability.

To identify barriers to and enablers of the informed healthcare consent process for people with intellectual disability, and to understand how this can be made equitable and accessible.

A systematic literature review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocols (PRISMA-P) systematic literature review protocol. 35 The PRISMA 2020 checklist 36 and ENhancing Transparency in REporting the synthesis of Qualitative research (ENTREQ) reporting guidelines were also followed. 37 The full study protocol is included in online supplemental appendix 1 .

Supplemental material

No patients or members of the public were involved in this research for this manuscript.

Search strategy

A search strategy was developed to identify articles about intellectual disability, consent and healthcare interventions, described in online supplemental appendix 2 . Multiple databases were searched for articles published between January 1990 to January 2022 (Embase, MEDLINE, PsychINFO, PubMed, SCOPUS, Web of Science and CINAHL). These databases include healthcare and psychology databases that best capture relevant literature on this topic, including medical, nursing, social sciences and bioethical literature. The search was limited to studies published from 1990 as understandings of consent have changed since then. 38 39 This yielded 4853 unique papers which were imported into Covidence, a specialised programme for conducting systematic reviews. 40

Study selection

Citation screening by abstract and titles was completed by two independent researchers (MD and EEP). Included articles had to:

Examine the informed consent process for a healthcare intervention for people with intellectual disability.

Have collected more than 50% of its data from relevant stakeholders, including adults with intellectual disability, families or carers of a person with intellectual disability, and professionals who engage with people with intellectual disability.

Report empirical data from primary research methodology.

Be published in a peer-reviewed journal after January 1990.

Be available in English.

Full text screening was completed by two independent researchers (MD and EEP). Articles were excluded if consent was only briefly discussed or if it focused on consent for research, capacity assessment, or participant knowledge or comprehension. Any conflicts were resolved through discussion with an independent third researcher (IS).

Additional studies were identified through an ancestral search and by hand-searching three major journals relevant to intellectual disability research. Journals were selected if they had published more than one included article for this review or in previous literature reviews conducted by the research team.

Quality assessment

Two independent researchers (MD and IS) assessed study quality with the QualSyst tool, 41 which can assess both qualitative and quantitative research papers. After evaluating the distribution of scores, a threshold value of 55% was used, as suggested by QualSyst 41 to exclude poor-quality studies but capture enough studies overall. Any conflicts between the quality assessment scores were resolved by a third researcher (EEP). For mixed-method studies, both qualitative and quantitative quality scores were calculated, and the higher value used.

Data collection

Two independent researchers (MD and JH) reviewed each study and extracted relevant details, including study size, participant demographics, year, country of publication, study design, data analysis and major outcomes reported. Researchers used standardised data collection forms designed, with input from senior researchers with expertise in qualitative research (IS and EEP), to extract data relevant to the review’s research aims. The form was piloted on one study, and a second iteration made based on feedback. These forms captured data on study design, methods, participants, any factors affecting the process of informed consent and study limitations. Data included descriptions and paragraphs outlining key findings, the healthcare context, verbatim participant quotes and any quantitative analyses or statistics. Missing or unclear data were noted.

Data analysis

A pilot literature search showed significant heterogeneity in methodology of studies, limiting the applicability of traditional quantitative analysis (ie, meta-analysis). Instead, inductive thematic analysis was chosen as an alternative methodology 42 43 that has been used in recent systematic reviews examining barriers and enablers of other health processes. 44 45 The six-phase approach described by Braun and Clarke was used. 46 47 A researcher (MD) independently coded the extracted data of each study line-by-line, with subsequent data grouped into pre-existing codes or new concepts when necessary. Codes were reviewed iteratively and grouped into categories, subthemes and themes framed around the research question. Another independent researcher (JH) collated and analysed the data on study demographics, methods and limitations. The themes were reviewed by two senior researchers (EEP and IS).

Qualitative methods of effect size calculations have been described in the literature, 48 49 which was captured in this review by the number of studies that identified each subtheme, with an assigned frequency rating to compare their relative significance. Subthemes were given a frequency rating of A, B, C or D if they were identified by >10, 7–9, 4–6 or <3 articles, respectively. The overall significance of each theme was estimated by the number of studies that mentioned it and the GRADE framework, a stepwise approach to quality assessment using a four-tier rating system. Each study was evaluated for risk of bias, inconsistency, indirectness, imprecision and publication bias. 50 51 Study sensitivity was assessed by counting the number of distinct subthemes included. 52 The quality of findings was designated high, moderate or low depending on the frequency ratings, the QualSyst score and the GRADE scores of studies supporting the finding. Finally, the relative contributions of each study were evaluated by the number of subthemes described, guided by previously reported methods for qualitative reviews. 52

Co-research

The findings were reviewed by two co-researchers with intellectual disability (JL and SS), with over 30 years combined experience as members and employees of a self-advocacy organisation. Guidance on the findings and an easy read summary was produced in line with best-practice inclusive research 53 54 over multiple discussions. Input from two health professional researchers (MD and EEP) provided data triangulation and sense-checking of findings.

Twenty-three articles were identified ( figure 1 ): 14 qualitative, 6 quantitative and 3 mixed-methods. Two papers included the same population of study participants: McCarthy 55 and McCarthy, 56 but had different research questions. Fovargue et al 57 was excluded due to a quality score of 35%. Common quality limitations were a lack of verification procedures to establish credibility and limited researcher reflexivity. No studies were excluded due to language requirements (as all were in English) or age restrictions (all studies had majority adult participants).

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PRISMA 2020 flowchart for the systematic review. 36

Studies were published from 1999 to 2020 and involved participant populations from the UK (n=18), USA (n=3), Sweden (n=1) and Ireland (n=1). Participant numbers ranged from 9 to 604 (median 21), and participants included people with intellectual disability (n=817), health professionals (n=272), carers and support people (n=48), and other professionals that work with people with intellectual disability (n=137, community service agency directors, social workers, administrative staff and care home staff). Ages of participants ranged from 8 to 84 years, though only Aman et al 58 included participants <18 years of age. This study was included as the article states very few children were included. Studies examined consent in different contexts, including contraception and sexual health (6/23 articles), 58–60 medications (5/23 articles), 58–62 emergency healthcare, 63 cervical screening, 64 community referrals, 58–61 65 mental health, 66 hydrotherapy, 64 blood collection 67 and broad decision-making consent without a specific context. 65 68–71 A detailed breakdown of each study is included in online supplemental appendix 3 .

Six major themes were identified from the studies, summarised in figure 2 . An overview of included studies showing study sensitivity, effect size, QualSyst and GRADE scores is given in online supplemental appendix 4 . Studies with higher QualSyst and GRADE scores contributed more to this review’s findings and tended to include more subthemes; specifically, Rogers et al , 66 Sowney and Barr, 63 Höglund and Larsson, 72 and McCarthy 55 and McCarthy. 56 Figure 3 gives the easy read version of theme 1, with the full easy read summary in online supplemental appendix 5 .

Summary of the identified six themes and subthemes.

Theme 1 of the easy read summary.

Theme 1—Health professionals’ attitudes and lack of education about informed consent

Health professionals’ attitudes and practices were frequently (18/21) identified as factors affecting the informed consent process, with substantial evidence supporting this theme. Studies noted the lack of training for health professionals in supporting informed consent for people with intellectual disability, their desire for further education, and stereotypes and discrimination perpetuated by health professionals.

Lack of health professional education on informed consent and disability discrimination legislation

Multiple studies reported inconsistent informed consent practices, for various reasons: some reported that health professionals ‘forgot’ to or ‘did not realise consent was necessary’, 63 73 but inconsistent consent practices were also attributed to healthcare providers’ unfamiliarity with consent guidelines and poor education on this topic. Carlson et al 73 reported that only 44% of general practitioners (GPs) were aware of consent guidelines, and there was the misconception that consent was unnecessary for people with intellectual disability. Similarly, studies of psychologists 66 and nurses 63 found that many were unfamiliar with their obligations to obtain consent, despite the existence of anti-discrimination legislation. People with intellectual disability describe feeling discriminated against by health professionals, reflected in comments such as ‘I can tell, my doctor just thinks I’m stupid – I'm nothing to him’. 74 Poor consent practices by health professionals were observed in Goldsmith et al , 67 while health professionals surveyed by McCarthy 56 were unaware of their responsibility to provide accessible health information to women with intellectual disability. Improving health professional education and training was suggested by multiple studies as a way to remove this barrier. 63 65–67 69 73

Lack of training on best practices for health professions caring for people with intellectual disability

A lack of training in caring for and communicating with people with intellectual disability was also described by midwives, 72 psychologists, 66 nurses, 63 pharmacists 61 and GPs. 56 72 75 Health professionals lacked knowledge about best practice approaches to providing equitable healthcare consent processes through reasonable adjustments such as accessible health information, 56 60 66 longer appointments times, 60 72 simple English 62 67 and flexible approaches to patient needs. 63 72

Health professionals’ stereotyping and assumptions of incapacity

Underlying stereotypes contributed to some health professionals’ (including nurses, 63 GPs 56 and physiotherapists 64 ) belief that people with intellectual disability lack capacity and therefore, do not require opportunities for informed consent. 56 64 In a survey of professionals referring people with intellectual disability to a disability service, the second most common reason for not obtaining consent was ‘patient unable to understand’. 73

Proxy consent as an inappropriate alternative

People with intellectual disability are rarely the final decision-maker in their medical choices, with many health providers seeking proxy consent from carers, support workers and family members, despite its legal invalidity. In McCarthy’s study (2010), 18/23 women with intellectual disability said the decision to start contraception was made by someone else. Many GPs appeared unaware that proxy consent is invalid in the UK. 56 Similar reports came from people with intellectual disability, 55 56 60 64 69 76 health professionals (nurses, doctors, allied health, psychologists), 56 63 64 66 77 support people 64 77 and non-medical professionals, 65 73 and capacity was rarely documented. 56 62 77

Exclusion of people with intellectual disability from decision-making discussions

Studies described instances where health professionals made decisions for their patients with intellectual disability or coerced patients into a choice. 55 72 74 76 77 In Ledger et al 77 , only 62% of women with intellectual disability were involved in the discussion about contraception, and only 38% made the final decision, and others stated in Wiseman and Ferrie 74 : ‘I was not given the opportunity to explore the different options. I was told what one I should take’. Three papers outlined instances where the choices of people with intellectual disability were ignored despite possessing capacity 65 66 69 and when a procedure continued despite them withdrawing consent. 69

Theme 2—Inadequate accessible health information

Lack of accessible health information.

The lack of accessible health information was the most frequently identified subtheme (16/23 studies). Some studies reported that health professionals provided information to carers instead, 60 avoided providing easy read information due to concerns about ‘offending’ patients 75 or only provided verbal information. 56 67 Informed consent was supported when health professionals recognised the importance of providing medical information 64 and when it was provided in an accessible format. 60 Alternative approaches to health information were explored, including virtual reality 68 and in-person education sessions, 59 with varying results. Overall, the need to provide information in different formats tailored to an individual’s communication needs, rather than a ‘one size fits all’ approach, was emphasised by both people with intellectual disability 60 and health professionals. 66

Insufficient information provided

Studies described situations where insufficient information was provided to people with intellectual disability to make informed decisions. For example, some people felt the information from their GP was often too basic to be helpful (Fish et al 60 ) and wanted additional information on consent forms (Rose et al 78 ).

Theme 3—The involvement of support people

Support people (including carers, family members and group home staff) were identified in 11 articles as both enablers of and barriers to informed consent. The antagonistic nature of these findings and lower frequency of subthemes are reflected in the lower quality assessments of evidence.

Support people facilitated communication with health professionals

Some studies reported carers bridging communication barriers with health to support informed consent. 63 64 McCarthy 56 found 21/23 of women with intellectual disability preferred to see doctors with a support person due to perceived benefits: ‘Sometimes I don’t understand it, so they have to explain it to my carer, so they can explain it to me easier’. Most GPs in this study (93%) also agreed that support people aided communication.

Support people helped people with intellectual disability make decisions

By advocating for people with intellectual disability, carers encouraged decision-making, 64 74 provided health information, 74 77 emotional support 76 and assisted with reading or remembering health information. 55 58 76 Some people with intellectual disability explicitly appreciated their support person’s involvement, 60 such as in McCarthy’s 55 study where 18/23 participants felt supported and safer when a support person was involved.

Support people impeded individual autonomy

The study by Wiseman and Ferrie 74 found that while younger participants with intellectual disability felt family members empowered their decision-making, older women felt family members impaired their ability to give informed consent. This was reflected in interviews with carers who questioned the capacity of the person with intellectual disability they supported and stated they would guide them to pick the ‘best choice’ or even over-ride their choices. 64 Studies of psychologists and community service directors described instances where the decision of family or carers was prioritised over the wishes of the person with intellectual disability. 65 66 Some women with intellectual disability in McCarthy’s studies (2010, 2009) 55 56 appeared to have been coerced into using contraception by parental pressures or fear of losing group home support.

Theme 4—Systemic constraints within healthcare systems

Time restraints affect informed consent and accessible healthcare.

Resource limitations create time constraints that impair the consent process and have been identified as a barrier by psychologists, 66 GPs, 56 hospital nurses 63 and community disability workers. 73 Rogers et al 66 highlighted that a personalised approach that could improve informed decision-making is restricted by inflexible medical models. Only two studies described flexible patient-centred approaches to consent. 60 72 A survey of primary care practices in 2007 reported that most did not modify their cervical screening information for patients with intellectual disability because it was not practical. 75

Inflexible models of consent

Both people with intellectual disability 76 and health professionals 66 recognised that consent is traditionally obtained through one-off interactions prior to an intervention. Yet, for people with intellectual disability, consent should ideally be an ongoing process that begins before an appointment and continues between subsequent ones. Other studies have tended to describe one-off interactions where decision-making was not revisited at subsequent appointments. 56 60 72 76

Lack of systemic supports

In one survey, self-advocates highlighted a lack of information on medication for people with intellectual disability and suggested a telephone helpline and a centralised source of information to support consent. 60 Health professionals also want greater systemic support, such as a health professional specialised in intellectual disability care to support other staff, 72 or a pharmacist specifically to help patients with intellectual disability. 61 Studies highlighted a lack of guidelines about healthcare needs of people with intellectual disabilities such as contraceptive counselling 72 or primary care. 75

Theme 5—Person-centred informed consent

Ten studies identified factors related to a person-centred approach to informed consent, grouped below into three subthemes. Health professionals should tailor their practice when obtaining informed consent from people with intellectual disability by considering how these subthemes relate to the individual. Each subtheme was described five times in the literature with a relative frequency rating of ‘C’, contributing to overall lower quality scores.

Previous experience with decision-making

Arscott et al 71 found that the ability of people with intellectual disability to consent changed with their verbal and memory skills and in different clinical vignettes, supporting the view of ‘functional’ capacity specific to the context of the medical decision. Although previous experiences with decision-making did not influence informed consent in this paper, other studies suggest that people with intellectual disability accustomed to independent decision-making were more able to make informed medical decisions, 66 70 and those who live independently were more likely to make independent healthcare decisions. 56 Health professionals should be aware that their patients with intellectual disability will have variable experience with decision-making and provide individualised support to meet their needs.

Variable awareness about healthcare rights

Consent processes should be tailored to the health literacy of patients, including emphasising available choices and the option to refuse treatment. In some studies, medical decisions were not presented to people with intellectual disability as a choice, 64 and people with intellectual disability were not informed of their legal right to accessible health information. 56

Power differences and acquiescence

Acquiescence by people with intellectual disability due to common and repeated experiences of trauma—that is, their tendency to agree with suggestions made by carers and health professionals, often to avoid upsetting others—was identified as an ongoing barrier. In McCarthy’s (2009) interviews with women with intellectual disability, some participants implicitly rejected the idea that they might make their own healthcare decisions: ‘They’re the carers, they have responsibility for me’. Others appeared to have made decisions to appease their carers: ‘I have the jab (contraceptive injection) so I can’t be blamed for getting pregnant’. 55 Two studies highlighted that health professionals need to be mindful of power imbalances when discussing consent with people with intellectual disability to ensure the choices are truly autonomous. 61 66

Theme 6—Effective communication between health professionals and patients

Implementation of reasonable adjustments for verbal and written information.

Simple language was always preferred by people with intellectual disability. 60 67 Other communication aids used in decision-making included repetition, short sentences, models, pictures and easy read brochures. 72 Another reasonable adjustment is providing the opportunity to ask questions, which women with intellectual disability in McCarthy’s (2009) study reported did not occur. 55

Tailored communication methods including non-verbal communication

Midwives noted that continuity of care allows them to develop rapport and understand the communication preferences of people with intellectual disability. 72 This is not always possible; for emergency nurses, the lack of background information about patients with intellectual disability made it challenging to understand their communication preferences. 63 The use of non-verbal communication, such as body language, was noted as underutilised 62 66 and people with intellectual disability supported the use of hearing loops, braille and sign language. 60

To the best of our knowledge, this is the first systematic review investigating the barriers and enablers of the informed consent process for healthcare procedures for people with intellectual disability. The integrative review by Goldsmith et al 26 examined capacity assessment and shares only three articles with this systematic review. 69 71 73 Since the 2000s, there has been a paradigm shift in which capacity is no longer considered a fixed ability that only some individuals possess 38 39 but instead as ‘functional’: a flexible ability that changes over time and in different contexts, 79 reflected in Goldsmith’s review. An individual’s capacity can be supported through various measures, including how information is communicated and how the decision-making process is approached. 18 80 By recognising the barriers and enablers identified in this review, physicians can help ensure the consent process for their patients with intellectual disability is both valid and truly informed. This review has highlighted the problems of inaccessible health information, insufficient clinical education on how to make reasonable adjustments and lack of person-centred trauma-informed care.

Recommendations

Health professionals require training in the informed consent process for people with intellectual disability, particularly in effective and respectful communication, reasonable adjustments and trauma-informed care. Reasonable adjustments include offering longer or multiple appointments, using accessible resources (such as easy read information or shared decision-making tools) and allowing patient choices (such as to record a consultation or involve a support person). Co-researchers reported that many people with intellectual disability prefer to go without a support person because they find it difficult to challenge their decisions and feel ignored if the health professional only talks to the support person. People with intellectual disability also feel they cannot seek second opinions before making medical decisions or feel pressured to provide consent, raising the possibility of coercion. These experiences contribute to healthcare trauma. Co-researchers raised the importance of building rapport with the person with intellectual disability and of making reasonable adjustments, such as actively advocating for the person’s autonomy, clearly stating all options including the choice to refuse treatment, providing opportunities to contribute to discussions and multiple appointments to ask questions and understand information. They felt that without these efforts to support consent, health professionals can reinforce traumatic healthcare experiences for people with intellectual disability. Co-researchers noted instances where choices were made by doctors without discussion and where they were only given a choice after requesting one and expressed concern that these barriers are greater for those with higher support needs.

Co-researchers showed how these experiences contributed to mistrust of health professionals and poorer health outcomes. In one situation, a co-researcher was not informed of a medication’s withdrawal effects, resulting in significant side-effects when it was ceased. Many people with intellectual disability describe a poor relationship with their health professionals, finding it difficult to trust health information provided due to previous traumatic experiences of disrespect, coercion, lack of choice and inadequate support. Many feel they cannot speak up due to the power imbalance and fear of retaliation. Poor consent practices and lack of reasonable adjustments directly harm therapeutic alliances by reducing trust, contribute to healthcare trauma and lead to poorer health outcomes for people with intellectual disability.

Additional education and training for health professionals is urgently needed in the areas of informed consent, reasonable adjustments and effective communication with people with intellectual disability. The experiences of health professionals within the research team confirmed that there is limited training in providing high-quality healthcare for people with intellectual disability, including reasonable adjustments and accessible health information. Co-researchers also suggested that education should be provided to carers and support people to help them better advocate for people with intellectual disability.

Health information should be provided in a multimodal format, including written easy read information. Many countries have regulation protecting the right to accessible health information and communication support to make an informed choice, such as UK’s Accessible Information Standard, 81 and Australia’s Charter of Health Care Rights, 24 yet these are rarely observed. Steps to facilitate this include routinely asking patients about information requirements, system alerts for an individual’s needs or routinely providing reasonable adjustments. 82 Co-researchers agreed that there is a lack of accessible health information, particularly about medications, and that diagrams and illustrations are underutilised. There is a critical need for more inclusive and accessible resources to help health professionals support informed consent in a safe and high-quality health system. These resources should be created through methods of inclusive research, such as co-production, actively involving people with intellectual disability in the planning, creation, and feedback process. 53

Strengths and limitations

This systematic review involved two co-researchers with intellectual disability in sense-checking findings and co-creating the easy read summary. Two co-authors who are health professionals provided additional sense-checking of findings from a different stakeholder perspective. In future research, this could be extended by involving people with intellectual disability in the design and planning of the study as per recommendations for best-practice inclusive research. 53 83

The current literature is limited by low use of inclusive research practices in research involving people with intellectual disability, increasing vulnerability to external biases (eg, inaccessible questionnaires, involvement of carers in data collection, overcompliance or acquiescence and absence of researcher reflexivity). Advisory groups or co-research with people with intellectual disability were only used in five studies. 58 60 68 74 76 Other limitations include unclear selection criteria, low sample sizes, missing data, using gatekeepers in patient selection and predominance of UK-based studies—increasing the risk of bias and reducing transferability. Nine studies (out of 15 involving people with intellectual disability) explicitly excluded those with severe or profound intellectual disability, reflecting a selection bias; only one study specifically focused on people with intellectual disability with higher support needs. Studies were limited to a few healthcare contexts, with a focus on consent about sexual health, contraception and medications.

The heterogeneity and qualitative nature of studies made it challenging to apply traditional meta-analysis. However, to promote consistency in qualitative research, the PRISMA and ENTREQ guidelines were followed. 36 37 Although no meta-analyses occurred, the duplication of study populations in McCarthy 2009 and 2010 likely contributed to increased significance of findings reported in both studies. Most included studies (13/23) were published over 10 years ago, reducing the current relevance of this review’s findings. Nonetheless, the major findings reflect underlying systemic issues within the health system, which are unlikely to have been resolved since the articles were published, as the just-released final report of the Australian Royal Commission into Violence, Abuse, Neglect and Exploitation of People with Disability highlights. 84 There is an urgent need for more inclusive studies to explore the recommendations and preferences of people with intellectual disability about healthcare choices.

Informed consent processes for people with intellectual disability should include accessible information and reasonable adjustments, be tailored to individuals’ needs and comply with consent and disability legislation. Resources, guidelines and healthcare education are needed and should cover how to involve carers and support people, address systemic healthcare problems, promote a person-centred approach and ensure effective communication. These resources and future research must use principles of inclusive co-production—involving people with intellectual disability at all stages. Additionally, research is needed on people with higher support needs and in specific contexts where informed consent is vital but under-researched, such as cancer screening, palliative care, prenatal and newborn screening, surgical procedures, genetic medicine and advanced therapeutics such as gene-based therapies.

Ethics statements

Patient consent for publication.

Not applicable.

Ethics approval

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Supplementary materials

Supplementary data.

This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.

• Data supplement 1
• Data supplement 2
• Data supplement 3
• Data supplement 4
• Data supplement 5

Contributors MD, EEP and IS conceived the idea for the systematic review. MD drafted the search strategy which was refined by EEP and IS. MD and EEP completed article screening. MD and IS completed quality assessments of included articles. MD and JH completed data extraction. MD drafted the original manuscript. JL and SS were co-researchers who sense-checked findings and were consulted to formulate dissemination plans. JL and SS co-produced the easy read summary with MD, CM, JH, EEP and IS. MD, JLS, EEP and IS reviewed manuscript wording. All authors critically reviewed the manuscript and approved it for publication. The corresponding author attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted. MD is the guarantor responsible for the overall content of this manuscript.

Funding This systematic literature review was funded by the National Health & Medical Research Council (NHMRC), Targeted Call for Research (TCR) into Improving health of people with intellectual disability. Research grant title "GeneEQUAL: equitable and accessible genomic healthcare for people with intellectual disability". NHMRC application ID: 2022/GNT2015753.

Competing interests None declared.

Provenance and peer review Not commissioned; externally peer reviewed.

Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.

Linked Articles

• Editorial It is up to healthcare professionals to talk to us in a way that we can understand: informed consent processes in people with an intellectual disability Jonathon Ding Richard Keagan-Bull Irene Tuffrey-Wijne BMJ Quality & Safety 2024; 33 277-279 Published Online First: 30 Jan 2024. doi: 10.1136/bmjqs-2023-016830

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Katharine Julia Hurry, Dilhara Karunaratne, Suzanne Westley, Alessandra Booth, Keith C R B Ramesar, Ting Ting Zhang, Michael Williams, David C Howlett, Ultrasound-guided core biopsy in the diagnosis of parotid neoplasia: an overview and update with a review of the literature, British Journal of Radiology , Volume 95, Issue 1130, 1 February 2022, 20210972, https://doi.org/10.1259/bjr.20210972

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Accurate diagnosis of parotid neoplasia is a key to determine the most appropriate patient management choice, including the need for surgery. This review provides an update of the literature on current practice and outcomes of parotid tissue sampling techniques, with an emphasis on ultrasound-guided core biopsy (USCB) and comparison with fine needle aspiration cytology (FNAC).

A literature review of EMBASE, Medline, PubMed and Google Scholar was conducted.

USCB has higher sensitivity, specificity and lower non-diagnostic rates than optimized FNAC. It also has a significantly higher sensitivity for the detection of malignancy. Significant complications post-USCB are uncommon, with only one reported case of tumour seeding and no cases of permanent facial nerve dysfunction. The technique is less operator-dependent than FNAC, with less reported variation in results between institutions.

USCB can be considered as the optimum tool of choice for the diagnosis of parotid neoplasia. This would particularly be the case in centres utilizing FNAC with high non-diagnostic rates or reduced diagnostic accuracy when compared to USCB published data, or in centres establishing a new service.

An update of the role and outcomes of USCB in the diagnosis of parotid gland pathologies.

Research shows that USCB preforms better than FNAC, in terms of sensitivity and specificity, particularly in the case of malignant neoplasia.

Complications following USCB were found to be higher than that of FNAC; however, no long-term major complications following either method have been reported in the literature.

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