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

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

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

There are five key steps to writing a literature review:

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

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

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Table of contents

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

• Quick Run-through
• Step 1 & 2

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

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

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

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

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

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

Download Word doc Download Google doc

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

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

Make a list of keywords

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

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

Search for relevant sources

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

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

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

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

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

For each publication, ask yourself:

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

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

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

Take notes and cite your sources

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

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

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

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

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

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

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

Chronological

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

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

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

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

Methodological

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

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

Theoretical

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

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

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

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

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

As you write, you can follow these tips:

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

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

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

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

Scribbr slides are free to use, customize, and distribute for educational purposes.

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

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

 Statistics

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

Research bias

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

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

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

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

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

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

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

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

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

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How To Structure Your Literature Review

3 options to help structure your chapter.

By: Amy Rommelspacher (PhD) | Reviewer: Dr Eunice Rautenbach | November 2020 (Updated May 2023)

Writing the literature review chapter can seem pretty daunting when you’re piecing together your dissertation or thesis. As  we’ve discussed before , a good literature review needs to achieve a few very important objectives – it should:

• Demonstrate your knowledge of the research topic
• Identify the gaps in the literature and show how your research links to these
• Provide the foundation for your conceptual framework (if you have one)
• Inform your own  methodology and research design

To achieve this, your literature review needs a well-thought-out structure . Get the structure of your literature review chapter wrong and you’ll struggle to achieve these objectives. Don’t worry though – in this post, we’ll look at how to structure your literature review for maximum impact (and marks!).

But wait – is this the right time?

Deciding on the structure of your literature review should come towards the end of the literature review process – after you have collected and digested the literature, but before you start writing the chapter. 

In other words, you need to first develop a rich understanding of the literature before you even attempt to map out a structure. There’s no use trying to develop a structure before you’ve fully wrapped your head around the existing research.

Equally importantly, you need to have a structure in place before you start writing , or your literature review will most likely end up a rambling, disjointed mess. 

Importantly, don’t feel that once you’ve defined a structure you can’t iterate on it. It’s perfectly natural to adjust as you engage in the writing process. As we’ve discussed before , writing is a way of developing your thinking, so it’s quite common for your thinking to change – and therefore, for your chapter structure to change – as you write. 

Need a helping hand?

Like any other chapter in your thesis or dissertation, your literature review needs to have a clear, logical structure. At a minimum, it should have three essential components – an  introduction , a  body   and a  conclusion . 

Let’s take a closer look at each of these.

1: The Introduction Section

Just like any good introduction, the introduction section of your literature review should introduce the purpose and layout (organisation) of the chapter. In other words, your introduction needs to give the reader a taste of what’s to come, and how you’re going to lay that out. Essentially, you should provide the reader with a high-level roadmap of your chapter to give them a taste of the journey that lies ahead.

Here’s an example of the layout visualised in a literature review introduction:

Your introduction should also outline your topic (including any tricky terminology or jargon) and provide an explanation of the scope of your literature review – in other words, what you  will   and  won’t   be covering (the delimitations ). This helps ringfence your review and achieve a clear focus . The clearer and narrower your focus, the deeper you can dive into the topic (which is typically where the magic lies). 

Depending on the nature of your project, you could also present your stance or point of view at this stage. In other words, after grappling with the literature you’ll have an opinion about what the trends and concerns are in the field as well as what’s lacking. The introduction section can then present these ideas so that it is clear to examiners that you’re aware of how your research connects with existing knowledge .

2: The Body Section

The body of your literature review is the centre of your work. This is where you’ll present, analyse, evaluate and synthesise the existing research. In other words, this is where you’re going to earn (or lose) the most marks. Therefore, it’s important to carefully think about how you will organise your discussion to present it in a clear way. 

The body of your literature review should do just as the description of this chapter suggests. It should “review” the literature – in other words, identify, analyse, and synthesise it. So, when thinking about structuring your literature review, you need to think about which structural approach will provide the best “review” for your specific type of research and objectives (we’ll get to this shortly).

There are (broadly speaking)  three options  for organising your literature review.

Option 1: Chronological (according to date)

Organising the literature chronologically is one of the simplest ways to structure your literature review. You start with what was published first and work your way through the literature until you reach the work published most recently. Pretty straightforward.

The benefit of this option is that it makes it easy to discuss the developments and debates in the field as they emerged over time. Organising your literature chronologically also allows you to highlight how specific articles or pieces of work might have changed the course of the field – in other words, which research has had the most impact . Therefore, this approach is very useful when your research is aimed at understanding how the topic has unfolded over time and is often used by scholars in the field of history. That said, this approach can be utilised by anyone that wants to explore change over time .

For example , if a student of politics is investigating how the understanding of democracy has evolved over time, they could use the chronological approach to provide a narrative that demonstrates how this understanding has changed through the ages.

Here are some questions you can ask yourself to help you structure your literature review chronologically.

• What is the earliest literature published relating to this topic?
• How has the field changed over time? Why?
• What are the most recent discoveries/theories?

In some ways, chronology plays a part whichever way you decide to structure your literature review, because you will always, to a certain extent, be analysing how the literature has developed. However, with the chronological approach, the emphasis is very firmly on how the discussion has evolved over time , as opposed to how all the literature links together (which we’ll discuss next ).

Option 2: Thematic (grouped by theme)

The thematic approach to structuring a literature review means organising your literature by theme or category – for example, by independent variables (i.e. factors that have an impact on a specific outcome).

As you’ve been collecting and synthesising literature , you’ll likely have started seeing some themes or patterns emerging. You can then use these themes or patterns as a structure for your body discussion. The thematic approach is the most common approach and is useful for structuring literature reviews in most fields.

For example, if you were researching which factors contributed towards people trusting an organisation, you might find themes such as consumers’ perceptions of an organisation’s competence, benevolence and integrity. Structuring your literature review thematically would mean structuring your literature review’s body section to discuss each of these themes, one section at a time.

Here are some questions to ask yourself when structuring your literature review by themes:

• Are there any patterns that have come to light in the literature?
• What are the central themes and categories used by the researchers?
• Do I have enough evidence of these themes?

PS – you can see an example of a thematically structured literature review in our literature review sample walkthrough video here.

Option 3: Methodological

The methodological option is a way of structuring your literature review by the research methodologies used . In other words, organising your discussion based on the angle from which each piece of research was approached – for example, qualitative , quantitative or mixed  methodologies.

Structuring your literature review by methodology can be useful if you are drawing research from a variety of disciplines and are critiquing different methodologies. The point of this approach is to question  how  existing research has been conducted, as opposed to  what  the conclusions and/or findings the research were.

For example, a sociologist might centre their research around critiquing specific fieldwork practices. Their literature review will then be a summary of the fieldwork methodologies used by different studies.

Here are some questions you can ask yourself when structuring your literature review according to methodology:

• Which methodologies have been utilised in this field?
• Which methodology is the most popular (and why)?
• What are the strengths and weaknesses of the various methodologies?
• How can the existing methodologies inform my own methodology?

3: The Conclusion Section

Once you’ve completed the body section of your literature review using one of the structural approaches we discussed above, you’ll need to “wrap up” your literature review and pull all the pieces together to set the direction for the rest of your dissertation or thesis.

The conclusion is where you’ll present the key findings of your literature review. In this section, you should emphasise the research that is especially important to your research questions and highlight the gaps that exist in the literature. Based on this, you need to make it clear what you will add to the literature – in other words, justify your own research by showing how it will help fill one or more of the gaps you just identified.

Last but not least, if it’s your intention to develop a conceptual framework for your dissertation or thesis, the conclusion section is a good place to present this.

Example: Thematically Structured Review

In the video below, we unpack a literature review chapter so that you can see an example of a thematically structure review in practice.

Let’s Recap

In this article, we’ve  discussed how to structure your literature review for maximum impact. Here’s a quick recap of what  you need to keep in mind when deciding on your literature review structure:

• Just like other chapters, your literature review needs a clear introduction , body and conclusion .
• The introduction section should provide an overview of what you will discuss in your literature review.
• The body section of your literature review can be organised by chronology , theme or methodology . The right structural approach depends on what you’re trying to achieve with your research.
• The conclusion section should draw together the key findings of your literature review and link them to your research questions.

If you’re ready to get started, be sure to download our free literature review template to fast-track your chapter outline.

Psst… there’s more!

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

29 Comments

Great work. This is exactly what I was looking for and helps a lot together with your previous post on literature review. One last thing is missing: a link to a great literature chapter of an journal article (maybe with comments of the different sections in this review chapter). Do you know any great literature review chapters?

I agree with you Marin… A great piece

I agree with Marin. This would be quite helpful if you annotate a nicely structured literature from previously published research articles.

Awesome article for my research.

I thank you immensely for this wonderful guide

It is indeed thought and supportive work for the futurist researcher and students

Very educative and good time to get guide. Thank you

Great work, very insightful. Thank you.

Thanks for this wonderful presentation. My question is that do I put all the variables into a single conceptual framework or each hypothesis will have it own conceptual framework?

Thank you very much, very helpful

This is very educative and precise . Thank you very much for dropping this kind of write up .

Pheeww, so damn helpful, thank you for this informative piece.

I’m doing a research project topic ; stool analysis for parasitic worm (enteric) worm, how do I structure it, thanks.

comprehensive explanation. Help us by pasting the URL of some good “literature review” for better understanding.

great piece. thanks for the awesome explanation. it is really worth sharing. I have a little question, if anyone can help me out, which of the options in the body of literature can be best fit if you are writing an architectural thesis that deals with design?

I am doing a research on nanofluids how can l structure it?

Beautifully clear.nThank you!

Lucid! Thankyou!

Brilliant work, well understood, many thanks

I like how this was so clear with simple language 😊😊 thank you so much 😊 for these information 😊

Insightful. I was struggling to come up with a sensible literature review but this has been really helpful. Thank you!

You have given thought-provoking information about the review of the literature.

Thank you. It has made my own research better and to impart your work to students I teach

I learnt a lot from this teaching. It’s a great piece.

I am doing research on EFL teacher motivation for his/her job. How Can I structure it? Is there any detailed template, additional to this?

You are so cool! I do not think I’ve read through something like this before. So nice to find somebody with some genuine thoughts on this issue. Seriously.. thank you for starting this up. This site is one thing that is required on the internet, someone with a little originality!

I’m asked to do conceptual, theoretical and empirical literature, and i just don’t know how to structure it

Asking questions are actually fastidious thing if you are not understanding anything fully, but this article presents good understanding yet.

thank you SOOO much it is really helpful ..

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31 Literature Analysis Using PIE Method

The following literature analysis sample is paired with an outline illustrating the organizational strategy of each paragraph in relation to the PIE method, which is:

• Point: The main idea of a paragraph stating your interpretation or opinion
• Information:  Supporting details or examples illustrating the point (quotes, statistics, analysis)
• Explanation:  How the point supports the thesis in relation to the information

What is a Literature Analysis?

The purpose of a literature analysis is to investigate an author’s rhetorical choices in relation to purpose, context, audience, tone, and genre. Examples of such rhetorical choices include literary devices, plot, setting, character, overall structure, and style (word usage, point of view). A literature analysis should contain a thesis statement which presents a clear argument in the introduction paragraph(s). All supporting evidence in the body paragraphs should directly tie back to the main argument as well as the text itself, avoiding unnecessary plot summary when identifying the who, what, when, where, and how. Similarly, the conclusion should reinforce the main argument while summarizing supporting ideas, focusing on the “why” by explaining the importance of the author’s work based on his or her rhetorical strategy.

In this draft, I have underlined examples of direct citation and utilized track markings to identify my overall organizational strategy. Note the progression of my supporting ideas from paragraph to paragraph and how they relate back to my main point (thesis).

Literature Analysis Using PIE Method

This work is licensed under CC BY-NC-SA 4.0. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/4.0/

Writing That Works Copyright © 2021 by The Writing Center at The University of Baltimore is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License , except where otherwise noted.

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• http://orcid.org/0000-0003-0157-5319 Ahtisham Younas 1 , 2 ,
• http://orcid.org/0000-0002-7839-8130 Parveen Ali 3 , 4
• 1 Memorial University of Newfoundland , St John's , Newfoundland , Canada
• 2 Swat College of Nursing , Pakistan
• 3 School of Nursing and Midwifery , University of Sheffield , Sheffield , South Yorkshire , UK
• 4 Sheffield University Interpersonal Violence Research Group , Sheffield University , Sheffield , UK
• Correspondence to Ahtisham Younas, Memorial University of Newfoundland, St John's, NL A1C 5C4, Canada; ay6133{at}mun.ca

https://doi.org/10.1136/ebnurs-2021-103417

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Introduction

Literature reviews offer a critical synthesis of empirical and theoretical literature to assess the strength of evidence, develop guidelines for practice and policymaking, and identify areas for future research. 1 It is often essential and usually the first task in any research endeavour, particularly in masters or doctoral level education. For effective data extraction and rigorous synthesis in reviews, the use of literature summary tables is of utmost importance. A literature summary table provides a synopsis of an included article. It succinctly presents its purpose, methods, findings and other relevant information pertinent to the review. The aim of developing these literature summary tables is to provide the reader with the information at one glance. Since there are multiple types of reviews (eg, systematic, integrative, scoping, critical and mixed methods) with distinct purposes and techniques, 2 there could be various approaches for developing literature summary tables making it a complex task specialty for the novice researchers or reviewers. Here, we offer five tips for authors of the review articles, relevant to all types of reviews, for creating useful and relevant literature summary tables. We also provide examples from our published reviews to illustrate how useful literature summary tables can be developed and what sort of information should be provided.

Tip 1: provide detailed information about frameworks and methods

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Tabular literature summaries from a scoping review. Source: Rasheed et al . 3

The provision of information about conceptual and theoretical frameworks and methods is useful for several reasons. First, in quantitative (reviews synthesising the results of quantitative studies) and mixed reviews (reviews synthesising the results of both qualitative and quantitative studies to address a mixed review question), it allows the readers to assess the congruence of the core findings and methods with the adapted framework and tested assumptions. In qualitative reviews (reviews synthesising results of qualitative studies), this information is beneficial for readers to recognise the underlying philosophical and paradigmatic stance of the authors of the included articles. For example, imagine the authors of an article, included in a review, used phenomenological inquiry for their research. In that case, the review authors and the readers of the review need to know what kind of (transcendental or hermeneutic) philosophical stance guided the inquiry. Review authors should, therefore, include the philosophical stance in their literature summary for the particular article. Second, information about frameworks and methods enables review authors and readers to judge the quality of the research, which allows for discerning the strengths and limitations of the article. For example, if authors of an included article intended to develop a new scale and test its psychometric properties. To achieve this aim, they used a convenience sample of 150 participants and performed exploratory (EFA) and confirmatory factor analysis (CFA) on the same sample. Such an approach would indicate a flawed methodology because EFA and CFA should not be conducted on the same sample. The review authors must include this information in their summary table. Omitting this information from a summary could lead to the inclusion of a flawed article in the review, thereby jeopardising the review’s rigour.

Tip 2: include strengths and limitations for each article

Critical appraisal of individual articles included in a review is crucial for increasing the rigour of the review. Despite using various templates for critical appraisal, authors often do not provide detailed information about each reviewed article’s strengths and limitations. Merely noting the quality score based on standardised critical appraisal templates is not adequate because the readers should be able to identify the reasons for assigning a weak or moderate rating. Many recent critical appraisal checklists (eg, Mixed Methods Appraisal Tool) discourage review authors from assigning a quality score and recommend noting the main strengths and limitations of included studies. It is also vital that methodological and conceptual limitations and strengths of the articles included in the review are provided because not all review articles include empirical research papers. Rather some review synthesises the theoretical aspects of articles. Providing information about conceptual limitations is also important for readers to judge the quality of foundations of the research. For example, if you included a mixed-methods study in the review, reporting the methodological and conceptual limitations about ‘integration’ is critical for evaluating the study’s strength. Suppose the authors only collected qualitative and quantitative data and did not state the intent and timing of integration. In that case, the strength of the study is weak. Integration only occurred at the levels of data collection. However, integration may not have occurred at the analysis, interpretation and reporting levels.

Tip 3: write conceptual contribution of each reviewed article

While reading and evaluating review papers, we have observed that many review authors only provide core results of the article included in a review and do not explain the conceptual contribution offered by the included article. We refer to conceptual contribution as a description of how the article’s key results contribute towards the development of potential codes, themes or subthemes, or emerging patterns that are reported as the review findings. For example, the authors of a review article noted that one of the research articles included in their review demonstrated the usefulness of case studies and reflective logs as strategies for fostering compassion in nursing students. The conceptual contribution of this research article could be that experiential learning is one way to teach compassion to nursing students, as supported by case studies and reflective logs. This conceptual contribution of the article should be mentioned in the literature summary table. Delineating each reviewed article’s conceptual contribution is particularly beneficial in qualitative reviews, mixed-methods reviews, and critical reviews that often focus on developing models and describing or explaining various phenomena. Figure 2 offers an example of a literature summary table. 4

Tabular literature summaries from a critical review. Source: Younas and Maddigan. 4

Tip 4: compose potential themes from each article during summary writing

While developing literature summary tables, many authors use themes or subthemes reported in the given articles as the key results of their own review. Such an approach prevents the review authors from understanding the article’s conceptual contribution, developing rigorous synthesis and drawing reasonable interpretations of results from an individual article. Ultimately, it affects the generation of novel review findings. For example, one of the articles about women’s healthcare-seeking behaviours in developing countries reported a theme ‘social-cultural determinants of health as precursors of delays’. Instead of using this theme as one of the review findings, the reviewers should read and interpret beyond the given description in an article, compare and contrast themes, findings from one article with findings and themes from another article to find similarities and differences and to understand and explain bigger picture for their readers. Therefore, while developing literature summary tables, think twice before using the predeveloped themes. Including your themes in the summary tables (see figure 1 ) demonstrates to the readers that a robust method of data extraction and synthesis has been followed.

Tip 5: create your personalised template for literature summaries

Often templates are available for data extraction and development of literature summary tables. The available templates may be in the form of a table, chart or a structured framework that extracts some essential information about every article. The commonly used information may include authors, purpose, methods, key results and quality scores. While extracting all relevant information is important, such templates should be tailored to meet the needs of the individuals’ review. For example, for a review about the effectiveness of healthcare interventions, a literature summary table must include information about the intervention, its type, content timing, duration, setting, effectiveness, negative consequences, and receivers and implementers’ experiences of its usage. Similarly, literature summary tables for articles included in a meta-synthesis must include information about the participants’ characteristics, research context and conceptual contribution of each reviewed article so as to help the reader make an informed decision about the usefulness or lack of usefulness of the individual article in the review and the whole review.

In conclusion, narrative or systematic reviews are almost always conducted as a part of any educational project (thesis or dissertation) or academic or clinical research. Literature reviews are the foundation of research on a given topic. Robust and high-quality reviews play an instrumental role in guiding research, practice and policymaking. However, the quality of reviews is also contingent on rigorous data extraction and synthesis, which require developing literature summaries. We have outlined five tips that could enhance the quality of the data extraction and synthesis process by developing useful literature summaries.

• Aromataris E ,
• Rasheed SP ,

Twitter @Ahtisham04, @parveenazamali

Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

Competing interests None declared.

Patient consent for publication Not required.

Provenance and peer review Not commissioned; externally peer reviewed.

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Introduction

Literature reviews take time. here is some general information to know before you start.  .

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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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Utilizing tables, figures, charts and graphs to enhance the readability of a research paper

Department of Pediatrics, College of Medicine and Health Sciences, National University of Science and Technology, Sohar, Sultanate of Oman

1 Department of Pediatrics, Seth G.S. Medical College and KEM Hospital, Mumbai, Maharashtra, India

Introduction

Every author aims to reach the maximum target audience through his/her research publication/s. Our previous editorials have touched upon the process of writing a quality research paper and its successful publication in an appropriate journal.[ 1 , 2 ] Journal-specific ”Instructions for Authors” generally have defined limits to the text and non-textual content for the benefit of space and presentation. Though the aim of a paper is to get its research point across through methodology, results, and discussion, readers often read the summary of data and analysis (only). Thus, the tables, figures, charts, and graphs are time and space-effective tools that not only help to understand the research presented in a simple manner but also engage and sustain the reader's interest.

Why use tables/figures/charts or graphs?

Reading text matter can often get monotonous – for the readers as well as the editors and reviewers. Using Tables/Figures/Charts or Graphs effectively provides a break from textual content monotony as well as provides an opportunity to process and connect information between text and images, promoting deeper learning. It is suggested that one non-textual element should be used for every 1000 words in a manuscript, which generally amounts to two for every three print pages.[ 3 ] The use of tables/figures/charts/graphs not only reduces the word count but also complements the text effectively. Although the text focuses on explaining findings, outlining trends, and providing contextual information, non-textual content allows readers to understand characteristics, distribution, and relationships between data, and visualize statistics/abstract concepts in a powerful manner. High-quality tables and figures also increase the likelihood of a manuscript being accepted for publication.[ 4 ] Note that the figures/artwork needs to be uploaded as separate files for most of the journals.

The CONSORT statement ( www.equator-ntework.org ) provides guidelines on how to report outcome-specific information in a published clinical trial report; however there are no definite recommendations on how to present non-textual elements, and this varies from one journal to another. Authors tend to prepare them based on their own understanding, often without much thought, and repeat the information presented in the main text. Moreover, while some journals have dedicated editors and resources to redraw or edit figures/tables, others simply publish whatever the authors submit. Thus, to improve the readability of the paper, it is primarily the author's responsibility to submit clear and useful tables, figures, charts, and graphs.

The heart of any research lies in its data, and most readers only get a glimpse of the data via the results. The closest one can get to raw statistics is through data presented in tables, figures, graphs, and supplementary material. Tables, figures, and graphs also help to classify and interpret data, highlight key findings, and present maximum data in a concise space. The author should make a deliberate decision on the presentation of his data early in the writing process. Using a sentence as text is more efficient while presenting up to half a dozen numbers in data or if the information can be summarized in three or lesser sentences.[ 5 ] Figures give an overall picture of concept (but without exact numerical data), while tables present exact values (but are less engaging and less interesting).[ 5 ] The final choice of the presentation depends on the type of data, statistical analysis, and relevant message to be delivered.[ 6 ]

General methodology of design and submission

The general structure followed by most non-textual elements is caption/legend/title, content, and footnotes. All data should be verified thoroughly for errors (especially outliers or unexpected spikes) and data sources should be cited in the footnotes/references. The presentation should be simple and clear enough for the reader to understand without any assumptions.[ 7 ] Each exhibit should be labeled clearly with a title and numbers (usually Arabic numerals) that are separate, unique, and consecutive based on their appearance in the text. The title should be self-explanatory and explain the information presented (what, where, and when) briefly. Footnotes should refer to restrictions, assumptions, abbreviations, explanatory notes, and unusual annotations. The formatting should be consistent throughout (across all tables/graphs) for easy comparison.[ 7 ] Design the figures, tables, and graphs to fit in one page on a scale that will be readable in print.[ 8 ] Always use the insert -> (arrow) page break function to ensure that each new Table/Figure/Graph is seen in the document on a new page. Data from the figures and tables should not be repeated in the text. Although tables/figures are often submitted separately or at the end of manuscript based on journal instructions, they should be referred to in the text at appropriate points by location statements i.e. Figures ​ Figures1 1 and ​ and2 2 or Tables ​ Tables1 1 and ​ and2 2 .[ 7 ] One should be careful during editing and proofreading, as contents and columns may get misplaced.[ 9 ] Ensure to follow the journal instructions regarding numbers and formats and glance through published examples in targeted journal. For additional data/tables/figures/graphs that do not fit into the journal's instructions or are still necessary to be displayed outside the word/Table limit, online appendages (or supplementary files) can be created. Do ask for feedback from experienced colleague/s (but not co-author) for the exhibit before final submissions.

A representative table already published in the JPGM earlier (reproduced from Shah S, Deshmukh CT, Tullu MS. The predictors of outcome and progression of pediatric sepsis and septic shock: A prospective observational study from western India. J Postgrad Med 2020;66:67-72 )

Representative figure/s already published in the JPGM earlier (reproduced from Mondkar SA, Tullu MS, Sathe P, Agrawal M. Lane-Hamilton syndrome – Is it really a needle in a haystack? J Postgrad Med 2022;68:162-7 )

Do’s and Don’ts while creating effective Tables.[ 8 , 9 , 12 , 14 , 15 ]

Types of graphical representations and their characteristics.[ 5 , 6 , 7 , 8 , 20 , 21 ]

Copyright issues

Material from government publications/public domain may be used without seeking permission; however, permission is required for all fully borrowed, adapted, or modified tables/figures/graphs not in the public domain, usually from the publishers, with appropriate credit notes in footnotes (as stated for the Journal of Postgraduate Medicine – JPGM).[ 9 , 10 ] All data sources should be identified for tables/figures created using information from other studies.[ 9 ] Authors should seek permissions from publishers early in their writing, as their research cannot be published until all written permissions have been submitted and approved.[ 9 ] It is good practice to maintain a copy of such permissions with the corresponding author in case a dispute arises later on.

Use of tables

Tables are meant to give a systematic overview of the results and provide a richer understanding/comprehension of study participant characteristics and principal research findings.[ 11 ] Since tables deal with larger groups of data, they are suitable when all data requires equal attention and readers can selectively scan the data of interest.[ 6 ] Tables can present precise numerical values and information with different units' side-by-side but may not analyze data trends.[ 6 ] However, due to the sheer amount of data, interpretation may take longer.[ 6 ]

Generally, the first table summarizes key characteristics of the study population allowing readers to assess the generalizability of the findings. Subsequent tables present details of associations/comparisons between variables, often crude findings followed by models adjusted for confounding factors.[ 11 ] Other tables include tables of lists, tables of inclusion/exclusion criteria for review, and summary of characteristics/results of study (systematic reviews) and characteristics of participants in narrative format (qualitative studies).[ 11 ]

A good table draws attention to the data and not the table itself; the reader should be able to express an opinion about results just by looking at it.[ 12 ] It should neither be too long nor wide; designing more rows than columns makes it easier to scan in portrait orientation.[ 9 , 11 ] JPGM guidelines permit a maximum of 10 columns and 25 rows in a table.[ 10 ] They are generally created from word documents as insert table and constructed before writing the content in text.[ 9 ] Most tables consist of five basic components: title, rows, columns, data fields, and footnotes. The title/legend should be concise but sufficiently informative.[ 13 ] The first column generally lists the independent variables in rows while subsequent columns present the dependent data. Column and row headings should include group sizes and measurement units (preferably an international system of units). Stubs (row headings) on the left side of a table describe row contents and should also list numerical definitions for the data i.e. the median ± SD (normal distribution), median with IQR (non-normally distributed data), or percentages (dichotomous data)[ 9 , 14 ] Use fewest decimal points necessary for accurate reporting of data.[ 14 ] Columns should present statistical analysis and significance ( P values) to highlight key findings.[ 14 ] Use well-labeled columns with the same format throughout (mean or percentiles).[ 3 ]

Each cell (data field) should contain only one numerical value and never be blank [use dash (-), ellipsis (…) or designate as “no data”]. Abbreviations should be limited; use abbreviations like “NA” very cautiously as it may be misinterpreted as not applicable/not available/not analyzed.[ 13 ] Combine tables when single variable is cross-tabulated or divide tables with too much of data.[ 7 ]

Footnotes should be brief, define abbreviations, statistical results ( P values and level of significance) and explain restrictions/discrepancies in the data. Footnotes should be ordered starting with the title of the table and working downwards from left to right. Symbols applying to the entire table should be in the title and those applying to the entire row/column should be after the row/column heading.[ 13 ] Most journals prefer superscripted letters instead of numbers. Symbols recommended by JPGM for footnotes (in order) are: *, †, ‡, §, ||, ¶, **, ††, ‡‡.[ 10 ]

Alignment and formatting: All text should be aligned to the left and numbers to the right.[ 7 ] Data fields with decimal points, hyphens/slashes, plus/minus symbols, or parentheses are aligned to these elements. For stubs continuing onto a second line, the corresponding data field should be aligned to the top line of the stub.[ 13 ] Tables can be made more meaningful, by converting data to ratios/percentages and sorting data as per the significance of variables, generally from left to right and top to bottom.[ 7 ] Data included in tables should conform with those in the main text, and percentages in rows and columns should sum up accurately.

Most journals have specific instructions for gridlines – only the top and bottom horizontal lines are used, with no vertical lines as columns are inherently aligned.[ 7 ] If tables are used from other publications, copyright permission should be obtained to reproduce them, and they should be appropriately referenced in the legend. There may be limitations as to the number of tables allowed depending on the Journal instructions and the type of article. Some Do's and Don'ts while creating tables are summarized in Table 1 .[ 8 , 9 , 12 , 14 , 15 ] Also, a representative table already published in the JPGM earlier has been reproduced herewith for better understanding [ Figure 1 ].

Use of figures

Figures are powerful communication tools that display patterns that are not visualized in the text or the tables. They can achieve a high educational impact by sustaining readers' interest and helping them understand trends, patterns, relationships among concepts and sequence of events.[ 3 ] Like tables, figures should be complete and self-explanatory. They should be designed thoughtfully, be relevant and be of good quality.[ 5 ] There may be limitations as to the number of figures allowed depending on the Journal instructions and type of the article. Figures can be statistical (graphs- as explained later) and non-statistical (clinical images, photographs, diagrams, illustrations and textual figures).[ 16 ] Non-statistical figures present visual information without data.[ 16 ] Clinical images and photographs [ultrasonograms, X-rays, computed tomography (CT) scans, magnetic resonance (MR) scans, images of patients, intraoperative photographs, tissue samples or microscopy findings] provide convincing and substantial information through illustrative examples from specific individuals and engage audiences, especially clinical professionals.[ 5 ] Illustrations help to explain structures, mechanisms, and relationships. Diagrams like “flowcharts”, “algorithms”, “pedigree charts”, and “maps” display complex relationships while “textual figures” describe steps of a procedure or summarize guidelines.

Structure: Figure legends (maximum of 40 words excluding credits) should be double-spaced and identified by consecutive Arabic numerals with the corresponding citation in the text. They reflect the data within, and consist of a brief title, experimental/statistical details, definitions of symbols/line or bar patterns and abbreviations/annotations.[ 15 ] Labels, numbers, and symbols should be clear, consistent, of uniform size and large enough to be legible after fitting figures to publication size.[ 15 ] Symbols, arrows, numbers, or letters used to identify parts of illustrations should be clearly identified, properly sized, placed, and explained in the legend. In case of photomicrographs, contrast the symbols/letters or arrows with background, and describe the internal scale (magnification) and method of staining.[ 10 ] If the figure has several parts (”collage”), they should be presented in order from left to right and top to bottom; this should be similarly followed for their description in the legend with labeling done as a, b, c, d, etc.[ 14 ]

Photos should have a minimum resolution of 300 dpi before digital manipulation, the acceptable formats for pictures/photos and figures in various journals being pdf, doc, ppt, jpg, gif, and tiff. Publication of color images may be chargeable which should be checked beforehand.[ 9 ] Often the print version of journal may present black and white images, with color images used in the online version.

Line diagrams: Black and white art with no shading often illustrates content better than a photograph, especially in the case of body anatomy or surgical techniques.[ 9 ] Their line weight should be consistent and not less than 0.25 pt. If scanned, they should be submitted as a tiff/jpeg image of at least 600 dpi and a width of 15 cm/6 inches.[ 14 ] Creating line diagrams may involve expensive professional help with issues of exclusive rights. Simple drawings can be scanned in a conventional office scanner at a minimum resolution of 600 dpi.[ 9 ] Drawings in shades of grey require a resolution of 1200 dpi or more, usually unavailable in regular office scanners.[ 9 ]

X-rays , which are photographic images, often lack good contrast, a problem magnified if the image must be enlarged. The quality of radiographs can be improved using Adobe Photoshop.[ 17 ] Figure captions in radiology should be utilized correctly and mention the modality, imaging plane and relevant technical information for images e.g. projection name on an x-ray, plane of a cross-sectional image, window setting of a CT section, and sequence name of an MR image.[ 17 ]

One may need to crop images to focus on the point of interest and maintain patient anonymity. Editing is usually done in tiff file format in software designed for image editing. Adjustments in brightness/contrast/color balance may help if raw image is not clear; however, it should not alter the meaning.[ 5 ] Colors should be easy to see (avoid yellow) and backgrounds should preferably be white. The tint should be no lower than 15%.[ 14 ] However, all digital modifications or enhancements of photographic images should be documented, step by step and the original raw files of unedited photographs/images should be available as supplementary files .[ 5 ]

Minimum resolution and design: Figures should be of high quality and resolution such that when final images are zoomed to 1600%, they should not blur or pixelate.[ 5 ] In case of reprints, care should be taken about picture quality.[ 3 ] JPGM requires a minimum resolution of 300 dpi or 1800 × 1600 pixels in TIFF format for digital images. Uploaded images should be within 4 MB in size and JPEG format. The JPGM also reserves the right to crop, rotate, reduce, or enlarge the photographs to an acceptable size.[ 10 ] One can use tools while creating figures and exporting data in another software; a few examples of open-source are Matplotlib (python plotting library), R, Inkscape, TikZ, PGF, GIMP, ImageMagick, D3 (Data-Driven-Documents), Cytoscape and Circos.[ 18 ]

Anonymity and Copyright: In the case of images, all unessential patient information or identifiers should be removed (masking or blurring only the eyes is no longer considered sufficient).[ 19 ] It is the author's responsibility to obtain written permission from the patient to use the photograph for educational purposes (whether the subject is identifiable or not) and archive it properly.[ 10 ] For images or descriptions that identify the patient, a statement about obtaining informed patient consent should be specified in the manuscript.[ 10 ] For figures published elsewhere, the original source should be acknowledged (via credit line in the figure legend) and the author should submit permission from copyright holder (usually the publisher) to reproduce the material before his/her manuscript is accepted.[ 3 , 19 ] Representative figure/s already published in the JPGM earlier have been reproduced herewith as an example [ Figure 2 ].

Use of graphs

Graphs allow the reader to visualize and compare data by highlighting patterns and relationships such as changes over time, frequency distribution, correlation, and relative share.[ 7 ] One should be precise with data values and presentation in graphs to avoid misinterpretation. Graphs can be created from data using the same software used for statistical analysis or by special programs. Depending on the results, data can be depicted in several different formats, such as line graphs, bar charts, data plots, maps, and pie charts.

What to use and when: The graphical format (bar graph, line graph, scatter lot, dot plot) can be decided based on the type of relationship to be shown. For example, line graphs demonstrate trends, bar graphs show magnitudes and pie charts show proportions.[ 9 , 16 ] The preferred graph also depends on the representative value of data – absolute value/fraction/average/median.[ 20 ] Graphs should accurately present findings, scale should start at zero and the axes should not be altered to make data meaningful.[ 15 ] Pie charts and 3D graphs are generally not recommended.[ 5 ] Table 2 summarizes different graphical formats with their brief description and uses.[ 5 , 6 , 7 , 8 , 20 , 21 ]

How to draw/construct: Most statistical programs create graphs with statistical computations. Special programs such as Prism and Sigmaplot can also be used.[ 14 ] Different formats can be visualized in the statistical program, and the one that best depicts the data can be chosen.[ 3 ] Actual numbers from which graphs are drawn should be provided.[ 10 ] Components of graphs include axes, labels, scales, tick/reference marks, symbols, and legends.[ 21 ] Independent variables are plotted on the horizontal axis while dependent variables on vertical axis.[ 4 ] Axis labels should be short, clear and indicate measurement variable/result, units, and number of group subjects (if any).[ 7 ] The axis scale should be proportional to data range so that visual data is not exaggerated/missed and minimum space is wasted.[ 20 ] Length of axes should be visually balanced (ratio of X to Y axis should be 1.0 to 1.3).[ 21 ] Provide explanations if the axis starts from non-zero values, is non-linear (logarithmic/exponential/rate) or scales before and after a break are different.[ 7 , 20 ] Symbols/lines/curves inside the two axes should be the most prominent features, wording in axes labels next prominent and axes and tick mark (outside of axes) least prominent.[ 21 ] Numbers and marks should be large enough to be legible even when compressed for print.[ 5 ] Symbols should be uniform and effectively used to designate important strata in figures. All graphs should be consistent in style and formatting. Footnotes should indicate P values (with appropriate statistical test) and discrepancies in data/items.[ 8 ]

A clear and concise legend (inside/outside) should describe the variables in the graph. It should also include values of lines, symbols and diagrams, abbreviations, acronyms as well as statistical tests, their levels of significance, sampling size, stains used for analysis, and magnification rate.[ 4 , 20 ] Annotations can highlight specific values/statistically significant differences in graphs.[ 20 ]

All unnecessary background lines (such as gridlines) are distracting and should be removed. The background should be the palest possible (preferably white) for the highest contrast and readability. Remove all default pre-styling formats and avoid 3D effects.[ 7 ] Data presentation can be intensified by eliminating clutter and refined in a vector graph editing program (without altering the position of marks representing data).[ 5 ] It is essential to minimize meaningless noise and maximize meaningful signals.[ 5 ]

Algorithms (combination of graph and table) are an excellent aid to demonstrate a decision tree. However, they can be difficult to construct due to decisions based on more than one variable. This presents clinical and technical difficulties in presenting all possible variations in a diagnosis or therapeutic decision.[ 9 ]

A representative graph and chart already published in the JPGM earlier has been reproduced herewith as an example [Figures ​ [Figures3 3 and ​ and4 4 ].

A representative graph already published in the JPGM earlier (reproduced from Bhatia S, Tullu MS, Kannan S, Gogtay NJ, Thatte UM, Lahiri KR. An unusual recurrence of antitubercular drug induced hepatotoxicity in a child. J Postgrad Med 2011;57:147-152 )

A representative chart already published in the JPGM earlier (reproduced from Agarwal S, Divecha C, Tullu MS, Deshmukh CT. A rare case of nephrotic syndrome: ‘Nailed’ the diagnosis. J Postgrad Med 2014;60:179-82 )

Use of supplementary materials

Supplementary materials refer to additional content (tables/graphs/appendices/videos/audios) that are not published in the main article. Scientific publications often come with strict word limits. Additional text or data which lengthens the print version can be accessed via digital supplementary files. Besides overcoming word restrictions, supplementary material provides additional information that is not essential in the main manuscript, but enhances understanding of research. They are available to interested readers to explore or replicate (methods/formulae/statistical models/algorithms/intervention pathways) the study for secondary research or teaching.[ 22 ] Thus, they serve as an online companion, complementing the main text. The most common supplementary files are tables and figures. Some instances of their use in various sections are as follows.[ 23 ]

In introduction: Table of summary of literature from various studies, detailed description of research topic, illustrations of concepts discussed, and glossaries of terms used.

In methodology: Participant details (sources, inclusion/exclusion lists, demography), instrumentation of constructs and variables, data collection techniques (survey questionnaires, participant forms), and data analysis techniques (coding sheets for content analysis, checklists) mathematical formulae used in calculations, data collection schedule.

In results and discussion: Additional results (often tables and figures), detailed analysis of limitations of the study or possible alternative explanations, programming code.

Other material includes references for supplementary files, translations, errata, audio, and video files.[ 23 ]

Examples of video/audio files include echocardiography recordings and ultrasound images. Specific information on the preparation of audio and video clips is available in the author guidelines. Video formats usually used are MPEG-4, QuickTime, or Windows media video. Audio supplements include WAV or MP3 format. Video size should be reduced to <10 MB and clips limited to 15–25 s. The resolution should be optimized by using video frame dimensions of 480 × 360 pixels and 640 × 480 pixels.[ 14 ]

However, supplemental material is available only in the online version- limiting immediate access to many readers.[ 5 ] Moreover, only readers with a strong interest in the research topic will access the online supplementary material.[ 5 ] The information in these files is often very extensive and not integrated with the main text appropriately, thus finding and extracting specific points from a supplement can be tedious.[ 24 ]

The utility of supplementary material varies as per the audience – additional tables and figures are more useful to readers, information about study protocol/data collection to peer reviewers, and completed checklists to journal editors. Due to the lack of guidance from journals (to both authors and reviewers) regarding its necessity or accuracy and due to the extensive nature of the files, supplementary material is rarely read/reviewed (though all the supplementary files are to be uploaded for peer-review with the main article files at the time of submission).[ 24 ] This increases the likelihood of missing errors in methods/analysis (submitted as supplementary files), thus placing the scientific accuracy and validity of the published research at risk.[ 24 ] Moreover, the availability of raw data to third parties via supplementary files raises concerns about security and data permanence.[ 22 ] The supplementary files often describe methods crucial to published research but are not included in references, thus many researchers remain uncited/unrecognized. Citations within supplementary material are also not appropriately tracked by citation indices. This can be overcome by direct hyperlinking sections of supplementary materials with the main manuscript.[ 24 ] Thus, supplementary data can be an asset if used thoughtfully; however, its indiscriminate use can hinder its actual purpose and be detrimental to the peer review process.

Concluding remarks

Tables, figures, graphs, and supplementary materials are vital tools which, when skillfully used, make complex data simple and clear to understand, within journal word restrictions. They engage and sustain interest and provide a brief visual summary narrative of study hypothesis- saving time and energy for readers, reviewers, and editors. They should be self-explanatory, complement the text and provide value to the paper. Producing clear, informative non-textual elements increases the chances of papers being published and read. Thus, the author should plan these elements early during the process of data collection/analysis and not as an afterthought. The author should have a good understanding of the types of data presentations and choose the simplest format that delivers his message best. They should be adapted to the journal's instructions to display and summarize essential content, without focusing too much on making it attractive or showcase one's technical expertise. Titles should be clear and simple, data should be consistent with results, and footnotes should be used effectively. Copyrights permissions, whenever necessary, should be obtained in advance and preserved appropriately.

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: .

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

Frequently asked questions 

What is a literature review .

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

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

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

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

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

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

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

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

Literature review example 

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

Literature Review on Climate Change Impacts on Biodiversity:  

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

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. 

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. 

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. 

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

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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. 

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

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

Conducting a literature review 

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

Choose a Topic and Define the Research Question:  

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

Decide on the Scope of Your Review:  

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

Select Databases for Searches:  

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

Conduct Searches and Keep Track:  

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

Review the Literature:  

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

Organize and Write Your Literature Review:  

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

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How to write a literature review faster with Paperpal?  

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• Cite with Confidence: Paperpal makes it easy to incorporate relevant citations and references in 10,000+ styles into your writing, ensuring your arguments are well-supported by credible sources. This translates to a polished, well-researched literature review. 

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

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

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

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

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

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

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

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

References 

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

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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.

Figures and Charts

What this handout is about.

This handout will describe how to use figures and tables to present complicated information in a way that is accessible and understandable to your reader.

Do I need a figure/table?

When planning your writing, it is important to consider the best way to communicate information to your audience, especially if you plan to use data in the form of numbers, words, or images that will help you construct and support your argument.  Generally speaking, data summaries may take the form of text, tables or figures. Most writers are familiar with textual data summaries and this is often the best way to communicate simple results. A good rule of thumb is to see if you can present your results clearly in a sentence or two. If so, a table or figure is probably unnecessary. If your data are too numerous or complicated to be described adequately in this amount of space, figures and tables can be effective ways of conveying lots of information without cluttering up your text. Additionally, they serve as quick references for your reader and can reveal trends, patterns, or relationships that might otherwise be difficult to grasp.

So what’s the difference between a table and a figure anyway?

Tables present lists of numbers or text in columns and can be used to synthesize existing literature, to explain variables, or to present the wording of survey questions. They are also used to make a paper or article more readable by removing numeric or listed data from the text. Tables are typically used to present raw data, not when you want to show a relationship between variables.

Figures are visual presentations of results. They come in the form of graphs, charts, drawings, photos, or maps.  Figures provide visual impact and can effectively communicate your primary finding. Traditionally, they are used to display trends and patterns of relationship, but they can also be used to communicate processes or display complicated data simply.  Figures should not duplicate the same information found in tables and vice versa.

Using tables

Tables are easily constructed using your word processor’s table function or a spread sheet program such as Excel. Elements of a table include the Legend or Title, Column Titles, and the Table Body (quantitative or qualitative data). They may also include subheadings and footnotes. Remember that it is just as important to think about the organization of tables as it is to think about the organization of paragraphs. A well-organized table allows readers to grasp the meaning of the data presented with ease, while a disorganized one will leave the reader confused about the data itself, or the significance of the data.

Title: Tables are headed by a number followed by a clear, descriptive title or caption. Conventions regarding title length and content vary by discipline. In the hard sciences, a lengthy explanation of table contents may be acceptable. In other disciplines, titles should be descriptive but short, and any explanation or interpretation of data should take place in the text. Be sure to look up examples from published papers within your discipline that you can use as a model. It may also help to think of the title as the “topic sentence” of the table—it tells the reader what the table is about and how it’s organized. Tables are read from the top down, so titles go above the body of the table and are left-justified.

Column titles: The goal of column headings is to simplify and clarify the table, allowing the reader to understand the components of the table quickly. Therefore, column titles should be brief and descriptive and should include units of analysis.

Table body: This is where your data are located, whether they are numerical or textual. Again, organize your table in a way that helps the reader understand the significance of the data. Be sure to think about what you want your readers to compare, and put that information in the column (up and down) rather than in the row (across). In other words, construct your table so that like elements read down, not across. When using numerical data with decimals, make sure that the decimal points line up. Whole numbers should line up on the right.

Other table elements

Tables should be labeled with a number preceding the table title; tables and figures are labeled independently of one another. Tables should also have lines demarcating different parts of the table (title, column headers, data, and footnotes if present). Gridlines or boxes should not be included in printed versions. Tables may or may not include other elements, such as subheadings or footnotes.

Quick reference for tables

Tables should be:

• Centered on the page.
• Numbered in the order they appear in the text.
• Referenced in the order they appear in the text.
• Labeled with the table number and descriptive title above the table.
• Labeled with column and/or row labels that describe the data, including units of measurement.
• Set apart from the text itself; text does not flow around the table.

Table 1. Physical characteristics of the Doctor in the new series of Doctor Who

Table 2. Physical characteristics of the Doctor in the new series of Doctor Who

Using figures

Figures can take many forms. They may be graphs, diagrams, photos, drawings, or maps. Think deliberately about your purpose and use common sense to choose the most effective figure for communicating the main point. If you want your reader to understand spatial relationships, a map or photograph may be the best choice. If you want to illustrate proportions, experiment with a pie chart or bar graph. If you want to illustrate the relationship between two variables, try a line graph or a scatterplot (more on various types of graphs below). Although there are many types of figures, like tables, they share some typical features: captions, the image itself, and any necessary contextual information (which will vary depending on the type of figure you use).

Figure captions

Figures should be labeled with a number followed by a descriptive caption or title. Captions should be concise but comprehensive. They should describe the data shown, draw attention to important features contained within the figure, and may sometimes also include interpretations of the data. Figures are typically read from the bottom up, so captions go below the figure and are left-justified.

The most important consideration for figures is simplicity. Choose images the viewer can grasp and interpret clearly and quickly. Consider size, resolution, color, and prominence of important features. Figures should be large enough and of sufficient resolution for the viewer to make out details without straining their eyes. Also consider the format your paper will ultimately take. Journals typically publish figures in black and white, so any information coded by color will be lost to the reader.  On the other hand, color might be a good choice for papers published to the web or for PowerPoint presentations. In any case, use figure elements like color, line, and pattern for effect, not for flash.

Additional information

Figures should be labeled with a number preceding the table title; tables and figures are numbered independently of one another. Also be sure to include any additional contextual information your viewer needs to understand the figure. For graphs, this may include labels, a legend explaining symbols, and vertical or horizontal tick marks. For maps, you’ll need to include a scale and north arrow. If you’re unsure about contextual information, check out several types of figures that are commonly used in your discipline.

Quick reference for figures

Figures should be:

• Labeled (under the figure) with the figure number and appropriate descriptive title (“Figure” can be spelled out [“Figure 1.”] or abbreviated [“Fig. 1.”] as long as you are consistent).
• Referenced in the order they appear in the text (i.e. Figure 1 is referenced in the text before Figure 2 and so forth).
• Set apart from the text; text should not flow around figures.

Every graph is a figure but not every figure is a graph. Graphs are a particular set of figures that display quantitative relationships between variables. Some of the most common graphs include bar charts, frequency histograms, pie charts, scatter plots, and line graphs, each of which displays trends or relationships within and among datasets in a different way. You’ll need to carefully choose the best graph for your data and the relationship that you want to show. More details about some common graph types are provided below. Some good advice regarding the construction of graphs is to keep it simple. Remember that the main objective of your graph is communication. If your viewer is unable to visually decode your graph, then you have failed to communicate the information contained within it.

Pie charts are used to show relative proportions, specifically the relationship of a number of parts to the whole. Use pie charts only when the parts of the pie are mutually exclusive categories and the sum of parts adds up to a meaningful whole (100% of something). Pie charts are good at showing “big picture” relationships (i.e. some categories make up “a lot” or “a little” of the whole thing). However, if you want your reader to discern fine distinctions within your data, the pie chart is not for you. Humans are not very good at making comparisons based on angles. We are much better at comparing length, so try a bar chart as an alternative way to show relative proportions. Additionally, pie charts with lots of little slices or slices of very different sizes are difficult to read, so limit yours to 5-7 categories.

The chart shows the relative proportion of fifteen elements in Martian soil, listed in order from “most” to “least”: oxygen, silicon, iron, magnesium, calcium, sulfur, aluminum, sodium, potassium, chlorine, helium, nitrogen, phosphorus, beryllium, and other. Oxygen makes up about ⅓ of the composition, while silicon and iron together make up about ¼. The remaining slices make up smaller proportions, but the percentages aren’t listed in the key and are difficult to estimate. It is also hard to distinguish fifteen colors when comparing the pie chart to the color coded key.

The chart shows the relative proportion of five leisure activities of Venusian teenagers (tanning, trips to Mars, reading, messing with satellites, and stealing Earth cable). Although each of the five slices are about the same size (roughly 20% of the total), the percentage of Venusian teenagers engaging in each activity varies widely (tanning: 80%, trips to Mars: 40%, reading: 12%, messing with satellites: 30%, stealing Earth cable: 77%). Therefore, there is a mismatch between the labels and the actual proportion represented by each activity (in other words, if reading represents 12% of the total, its slice should take up 12% of the pie chart area), which makes the representation inaccurate. In addition, the labels for the five slices add up to 239% (rather than 100%), which makes it impossible to accurately represent this dataset using a pie chart.

Bar graphs are also used to display proportions. In particular, they are useful for showing the relationship between independent and dependent variables, where the independent variables are discrete (often nominal) categories. Some examples are occupation, gender, and species. Bar graphs can be vertical or horizontal. In a vertical bar graph the independent variable is shown on the x axis (left to right) and the dependent variable on the y axis (up and down). In a horizontal one, the dependent variable will be shown on the horizontal (x) axis, the independent on the vertical (y) axis. The scale and origin of the graph should be meaningful. If the dependent (numeric) variable has a natural zero point, it is commonly used as a point of origin for the bar chart. However, zero is not always the best choice. You should experiment with both origin and scale to best show the relevant trends in your data without misleading the viewer in terms of the strength or extent of those trends.

The graph shows the number of male and female spaceship crew members for five different popular television series: Star Trek (1965), Battlestar (1978), Star Trek: TNG (1987), Stargate SG-1 (1997), and Firefly (2002). Because the television series are arranged chronologically on the x-axis, the graph can also be used to look for trends in these numbers over time.

Although the number of crew members for each show is similar (ranging from 9 to 11), the proportion of female and male crew members varies. Star Trek has half as many female crew members as male crew members (3 and 6, respectively), Battlestar has fewer than one-fourth as many female crew members as male crew members (2 and 9, respectively), Star Trek: TNG has four female crew members and six male crew members, Stargate SG-1 has less than one-half as many female crew members as male crew members (3 and 7, respectively), and Firefly has four female and five male crew members.

Frequency histograms/distributions

Frequency histograms are a special type of bar graph that show the relationship between independent and dependent variables, where the independent variable is continuous, rather than discrete. This means that each bar represents a range of values, rather than a single observation. The dependent variables in a histogram are always numeric, but may be absolute (counts) or relative (percentages). Frequency histograms are good for describing populations—examples include the distribution of exam scores for students in a class or the age distribution of the people living in Chapel Hill. You can experiment with bar ranges (also known as “bins”) to achieve the best level of detail, but each range or bin should be of uniform width and clearly labeled.

XY scatter plots

Scatter plots are another way to illustrate the relationship between two variables. In this case, data are displayed as points in an x,y coordinate system, where each point represents one observation along two axes of variation. Often, scatter plots are used to illustrate correlation between two variables—as one variable increases, the other increases (positive correlation) or decreases (negative correlation). However, correlation does not necessarily imply that changes in one variable cause changes in the other. For instance, a third, unplotted variable may be causing both. In other words, scatter plots can be used to graph one independent and one dependent variable, or they can be used to plot two independent variables. In cases where one variable is dependent on another (for example, height depends partly on age), plot the independent variable on the horizontal (x) axis, and the dependent variable on the vertical (y) axis. In addition to correlation (a linear relationship), scatter plots can be used to plot non-linear relationships between variables.

The scatter plot shows the relationship between temperature (x-axis, independent variable) and the number of UFO sightings (y-axis, dependent variable) for 53 separate data points. The temperature ranges from about 0°F and 120°F, and the number of UFO sightings ranges from 1 to 10. The plot shows a low number of UFO sightings (ranging from 1 to 4) at temperatures below 80°F and a much wider range of the number of sightings (from 1 to 10) at temperatures above 80°F. It appears that the number of sightings tends to increase as temperature increases, though there are many cases where only a few sightings occur at high temperatures.

XY line graphs

Line graphs are similar to scatter plots in that they display data along two axes of variation. Line graphs, however, plot a series of related values that depict a change in one variable as a function of another, for example, world population (dependent) over time (independent). Individual data points are joined by a line, drawing the viewer’s attention to local change between adjacent points, as well as to larger trends in the data. Line graphs are similar to bar graphs, but are better at showing the rate of change between two points. Line graphs can also be used to compare multiple dependent variables by plotting multiple lines on the same graph.

Example of an XY line graph:

The line graph shows the age (in years) of the actor of each Doctor Who regeneration for the first through the eleventh regeneration. The ages range from a maximum of about 55 in the first regeneration to a minimum of about 25 in the eleventh regeneration. There is a downward trend in the age of the actors over the course of the eleven regenerations.

General tips for graphs

Strive for simplicity. Your data will be complex. Don’t be tempted to convey the complexity of your data in graphical form. Your job (and the job of your graph) is to communicate the most important thing about the data. Think of graphs like you think of paragraphs—if you have several important things to say about your data, make several graphs, each of which highlights one important point you want to make.

Strive for clarity. Make sure that your data are portrayed in a way that is visually clear. Make sure that you have explained the elements of the graph clearly. Consider your audience. Will your reader be familiar with the type of figure you are using (such as a boxplot)? If not, or if you’re not sure, you may need to explain boxplot conventions in the text. Avoid “chartjunk.” Superfluous elements just make graphs visually confusing. Your reader does not want to spend 15 minutes figuring out the point of your graph.

Strive for accuracy. Carefully check your graph for errors. Even a simple graphical error can change the meaning and interpretation of the data. Use graphs responsibly. Don’t manipulate the data so that it looks like it’s saying something it’s not—savvy viewers will see through this ruse, and you will come off as incompetent at best and dishonest at worst.

How should tables and figures interact with text?

Placement of figures and tables within the text is discipline-specific. In manuscripts (such as lab reports and drafts) it is conventional to put tables and figures on separate pages from the text, as near as possible to the place where you first refer to it. You can also put all the figures and tables at the end of the paper to avoid breaking up the text. Figures and tables may also be embedded in the text, as long as the text itself isn’t broken up into small chunks. Complex raw data is conventionally presented in an appendix. Be sure to check on conventions for the placement of figures and tables in your discipline.

You can use text to guide the reader in interpreting the information included in a figure, table, or graph—tell the reader what the figure or table conveys and why it was important to include it.

When referring to tables and graphs from within the text, you can use:

• Clauses beginning with “as”: “As shown in Table 1, …”
• Passive voice: “Results are shown in Table 1.”
• Active voice (if appropriate for your discipline): “Table 1 shows that …”
• Parentheses: “Each sample tested positive for three nutrients (Table 1).”

Works consulted

We consulted these works while writing this handout. This is not a comprehensive list of resources on the handout’s topic, and we encourage you to do your own research to find additional publications. Please do not use this list as a model for the format of your own reference list, as it may not match the citation style you are using. For guidance on formatting citations, please see the UNC Libraries citation tutorial . We revise these tips periodically and welcome feedback.

American Psychological Association. 2010. Publication Manual of the American Psychological Association . 6th ed. Washington, DC: American Psychological Association.

Bates College. 2012. “ Almost everything you wanted to know about making tables and figures.” How to Write a Paper in Scientific Journal Style and Format , January 11, 2012. http://abacus.bates.edu/~ganderso/biology/resources/writing/HTWtablefigs.html.

Cleveland, William S. 1994. The Elements of Graphing Data , 2nd ed. Summit, NJ: Hobart Press..

Council of Science Editors. 2014. Scientific Style and Format: The CSE Manual for Authors, Editors, and Publishers , 8th ed. Chicago & London: University of Chicago Press.

University of Chicago Press. 2017. The Chicago Manual of Style , 17th ed. Chicago & London: University of Chicago Press.

You may reproduce it for non-commercial use if you use the entire handout and attribute the source: The Writing Center, University of North Carolina at Chapel Hill

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Literature Review Chart

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Usage Notes

Learning goals and assessments.

Learning Goal(s):

• Students will be able to articulate the themes or concepts shared in common across a body of scholarly literature and use these ideas to draft a competent mini-literature review.

Goal Assessment(s):

• After completing the template included in this resource, students should be asked to draft a 2-3 page literature review. A rubric for evaluating literature review drafts is included.

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How to Write a Stellar Literature Review

When you’re conducting academic research, a literature review is a survey of the scholarly sources you’ve consulted in your research. Typically, literature reviews are only necessary when you’re doing a significant academic project, such as a dissertation , research paper, or a  thesis . For shorter pieces of academic writing, including essays , your works cited page is sufficient. 

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When would I write a literature review?

As we mentioned above, writing a literature review is part of writing an academic paper. The purpose of writing a literature review is to present the  sources you’ve used in your research to your work’s readers. By doing this, you’re communicating several things:

• Research methodology: In other words, you’re explaining the type of research you conducted, how you conducted your research and collected your data, your reasons for choosing the sources you chose, and how you analyzed the data you collected.
• Theoretical framework you established : This is essentially a map of your research showing where you started, which concepts you chose to dive into deeply, and where following those concepts brought you. Generally, these concepts are theories and models established by academics in your field. 
• Where your work fits into the bigger picture: Here, you explain how your findings connect to the existing body of research on your topic. This means how it relates to other pieces of research, any existing gaps it fills, any debates to which it contributes, and where you fit in among others in your field. 

Writing a literature review is no small undertaking! But then again, neither is writing your thesis, dissertation, or even a lengthy, comprehensive research paper. 

In many cases, you’re required to write a literature review and submit it to your academic supervisor before getting started on your paper. This gives your supervisor the opportunity to see what you’re researching, how you’re conducting that research, and, if necessary, provide feedback and suggestions to make your research stronger. This could mean suggesting alternative sources or redirecting your research’s scope.

A literature review is not the same thing as an  abstract . Both are critical parts of a research project, but while an abstract summarizes your work, a literature review summarizes the research you conducted to complete your work. In many cases, an abstract’s goal is to engage readers and help researchers and cataloguers determine whether your work is a relevant source for their work and whether it’s a good fit for a specific collection or academic journal. A literature review’s goal is to provide a “behind the scenes” look at how you did your research, underpinning it as a valid piece of scholarly research. 

How to write a literature review

Literature review structure.

A literature review is  structured similarly to an essay . It begins with an introduction that states the research question and explains how you tackled it. Following are body paragraphs that explain your research in further detail. Then, it ends with a conclusion section that reiterates the research question while summarizing the insights you had through your research. 

A literature review’s length depends largely on the type of research it’s being written for. For a short paper, it might only be a few pages long, but for a lengthy work like a thesis or dissertation, it’s often an entire chapter. 

Literature review style

A literature review requires the same style as any other piece of  academic writing . That means no contractions or colloquialisms, concise language, formal tone, and an objective perspective at all times. 

To distinguish between your analysis and prior scholarly work in the field, use the past tense when discussing the previous research conducted on your topic and the present tense when discussing your point of view. For example, you might write that a specific author conducted research or that they had been influenced by earlier researchers in the field, but also that you are exploring different research methods and that you are posing certain questions. 

Writing a literature review, step-by-step

Define your research scope.

If you haven’t yet narrowed your research focus down to a specific, answerable question, do that before you move forward with finding sources. Once you have a clear, specific thesis for your work, write a list of keywords related to that thesis you can use to streamline your source-gathering process. 

Find relevant literature

Using the keywords you listed, search for relevant sources through your university library and/or databases like Google Scholar, JSTOR, EBSCO, and field-specific databases like Project Muse and EconLit. 

As you find potential sources, read their abstracts to determine whether they are within your research’s scope. By reading a quick preview of each source (and taking note of recurring authors, contributors, and citations) you can pare down your list to a collection of works that provide the data, insights, and additional content you need to conduct your research. 

Identify themes, patterns, and gaps within your body of sources

Read your pared-down body of sources. As you conduct your research, take note of the themes present in them and ask questions: 

• Do different authors agree with each other on these themes? 
• Where do they disagree? 
• How does each author support their position?

Examine the research methods each author used in their work. If your sources involve studies or experiments, note whether the results were replicated and where, if at all, the studies’ results varied from each other. 

Write down your key insights and how each source you consult contributes to the existing pool of knowledge on its subject. Explore how the sources challenge and contradict each other and where they agree or expand upon each other. 

Create a literature review outline

Writing an outline is an important part of the writing process . Once you’ve read your sources and you understand their themes, patterns, and connections to each other, it’s time to organize your strategy for writing about how you’ve used them in your research by creating an outline. 

There are a few different ways you can organize your outline. You can organize it chronologically , listing and discussing the oldest sources you’ve consulted and working up to the latest pieces. You can also organize your sources according to their themes , creating a section for each shared theme you encountered and discussing it there. Another way to organize your sources in your outline is to group them according to the research methods used by their authors. 

The best way to organize your literature review often depends on your subject area. In the humanities, presenting your sources chronologically or according to their themes can effectively highlight how existing research on your subject has evolved, whereas in the hard sciences, organizing your sources according to their research methods can enable you to highlight why the current scholarly consensus (if there is one!) is what it is. 

Write your literature review

Once your outline is complete, it’s time to start writing. In nearly all cases, literature reviews are written in the third person. For example, you might discuss a scholarly article by stating “this paper argues . . .” or “in her work, the author elaborates on . . .” However, there are cases where first person is appropriate in a literature review, such as when you’re referencing your own research. For example, if you’re citing an earlier paper you’ve written or data collected from a study you conducted, you may use phrases like “I argue,” “I propose,” and “through my research, I found that . . .”

Remember to follow the style you’re using for your research paper, whether that’s MLA , APA , or Chicago Manual of Style format. Similarly, use the same objective academic tone you’ll use in your research paper. Don’t just list and describe the sources you’ve read; respond to them, interpret them, and critically evaluate them. Keep in mind that you don’t have to agree with every source you use—in fact, exploring where your findings diverge from a source’s findings can be a strong point in your literature review and your research as a whole.  

Don’t forget to write an annotated bibliography of all your sources. Failing to cite your sources correctly can get you in trouble for plagiarism , which can potentially result in having your work discredited or even being expelled from your university. 

Literature review examples

Reading others’ literature reviews, especially literature reviews for research in your academic field, can be a very helpful way for you to understand how they work and see what you need to include in yours. 

Read the literature reviews of the sources you read in your own research. Your university might also have a resources page of literature review examples you can read. University of West Florida is one university that publishes literature review examples online .

Get academic writing just right

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That’s also why it’s so important to strike the right tone in your academic writing—and it’s a tone you don’t find in many other kinds of work. Grammarly does more than catch your grammar mistakes and unclear writing; it detects your tone and offers valuable suggestions you can use to polish your writing into its final, submission-ready version. 

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Statistics By Jim

Making statistics intuitive

Pie Charts: Using, Examples, and Interpreting

By Jim Frost 1 Comment

Use pie charts to compare the sizes of categories to the entire dataset. To create a pie chart, you must have a categorical variable that divides your data into groups. These graphs consist of a circle (i.e., the pie) with slices representing subgroups. The size of each slice is proportional to the relative size of each category out of the whole.

These charts can use proportions or summary statistics to determine the sizes of the slices. For example, you can create a pie chart that shows the proportion of each sales type (electronics, software, accessories, etc.). Or create one that displays total sales by those categories.

Pie charts shine when you need to assess the relative sizes of categories to the entire dataset.

At a minimum, pie charts require one categorical variable. To learn about other graphs, read my Guide to Data Types and How to Graph Them .

Example Pie Chart

A company wants to determine the proportion of employees in each job category.

Pie charts typically contain the following elements:

• Circle (“pie”) representing all observations.
• Circle segment (“pie slice”) for each category.
• Optionally, slices can have labels indicating their relative (percentage) or absolute size (count or summary statistic).

For the company, the largest category is manufacturing, followed by R&D.  The smallest group is janitorial.

Interpreting Pie Charts

Pie charts provide a broad overview of the categories you’re studying. By comparing and contrasting the size of the slices, you can evaluate the relative magnitude of each group. In the chart below, four colors (white, silver, black, and grey) comprise nearly three-quarters of all new car colors in 2012.

When assessing more than one pie chart, compare the sizes of the categories between charts. Understanding how the slices for the same groups change between pie charts can help you recognize the relationships in your data. The graph below displays total sales by category for two locations. The East location has relatively more Laptop sales and fewer Desktop sales than the West location. The two locations are approximately equal for Mobile and Software sales.

Limitations of Pie Charts and Comparing Them to Bar Charts

Pie charts effectively illustrate the different sizes for parts of the whole. However, these graphs have shortcomings that can limit their usage. To use a pie chart, consider the following:

• Use when your primary goal is to compare the parts to the whole.
• The category totals must add up to the overall total.
• Pie charts are best for simple data arrangements.

When these three points are true, pie charts are a compelling choice. People viewing them will understand the data easily. However, if these three points don’t apply to your data, consider a different graph. Pie charts require categorical data. Consequently, bar charts are an excellent alternative because they also use categorical data and have greater formatting flexibility.

Let’s explore a couple of these limitations in more detail.

Related post : Guide to Bar Charts

Parts Must Add Up to the Whole

Pie charts can display summary statistics for the categories, but the parts must sum up to the whole. For example, they can display total sales by group because the group sales add up to the total sales.

However, if you want to graph the average sales price per transaction by category, you can’t use a pie chart. Average sales by category do NOT add up to the average for all sales. In other words, average category sales are not parts of a whole and, therefore, inappropriate for pie charts.

Fortunately, category averages are just fine for bar charts because those graphs do not assume the variable function (i.e., average) represents parts of the whole.

Bar charts provide greater flexibility for choosing metrics to compare across groups because they don’t need to sum to the total value.

Too Many Categories and Too Few Formatting Options

Even when you have appropriate data where you are comparing parts to a whole, you might need to use a bar chart instead.

Maybe your data have many groups, and the slices become too small to identify. Perhaps you have two categorical variables and want to explore the relationship between them. Or your categories have subcategories.

Pie charts provide relatively few formatting options to handle more complex data arrangements. However, bar charts allow you to stack, cluster, and otherwise organize the bars in ways that can handle more complex data and many categories.

In short, pie charts are a fantastic option for comparing parts to a whole when you have a simple data arrangement with a reasonable number of categories. Unfortunately, various data issues can either be invalid or create pie charts that are hard to interpret. In these cases, consider using a bar chart, which is more flexible on all those fronts.

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July 23, 2024 at 1:56 pm

I’d be curious to see a pie chart of employment statistics. Broad catagories. Travel. Mfg. Fed govt. State govt. Local govt. Self Emp. And any other broad catagory. Another good stat. I wrote the OMB once and requested they send to me a pie chart of where and what my tax dollars were spent on. It was fascinating, but also disappointing.

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A Pie Chart displaying the distribution of reviewed articles by the journal database.

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