how to do introduction for literature review

How to write a literature review introduction (+ examples)

The introduction to a literature review serves as your reader’s guide through your academic work and thought process. Explore the significance of literature review introductions in review papers, academic papers, essays, theses, and dissertations. We delve into the purpose and necessity of these introductions, explore the essential components of literature review introductions, and provide step-by-step guidance on how to craft your own, along with examples.

Why you need an introduction for a literature review

When you need an introduction for a literature review, what to include in a literature review introduction, examples of literature review introductions, steps to write your own literature review introduction.

A literature review is a comprehensive examination of the international academic literature concerning a particular topic. It involves summarizing published works, theories, and concepts while also highlighting gaps and offering critical reflections.

In academic writing , the introduction for a literature review is an indispensable component. Effective academic writing requires proper paragraph structuring to guide your reader through your argumentation. This includes providing an introduction to your literature review.

It is imperative to remember that you should never start sharing your findings abruptly. Even if there isn’t a dedicated introduction section .

Instead, you should always offer some form of introduction to orient the reader and clarify what they can expect.

There are three main scenarios in which you need an introduction for a literature review:

• Academic literature review papers: When your literature review constitutes the entirety of an academic review paper, a more substantial introduction is necessary. This introduction should resemble the standard introduction found in regular academic papers.
• Literature review section in an academic paper or essay: While this section tends to be brief, it’s important to precede the detailed literature review with a few introductory sentences. This helps orient the reader before delving into the literature itself.
• Literature review chapter or section in your thesis/dissertation: Every thesis and dissertation includes a literature review component, which also requires a concise introduction to set the stage for the subsequent review.

You may also like: How to write a fantastic thesis introduction (+15 examples)

It is crucial to customize the content and depth of your literature review introduction according to the specific format of your academic work.

In practical terms, this implies, for instance, that the introduction in an academic literature review paper, especially one derived from a systematic literature review , is quite comprehensive. Particularly compared to the rather brief one or two introductory sentences that are often found at the beginning of a literature review section in a standard academic paper. The introduction to the literature review chapter in a thesis or dissertation again adheres to different standards.

Here’s a structured breakdown based on length and the necessary information:

Academic literature review paper

The introduction of an academic literature review paper, which does not rely on empirical data, often necessitates a more extensive introduction than the brief literature review introductions typically found in empirical papers. It should encompass:

• The research problem: Clearly articulate the problem or question that your literature review aims to address.
• The research gap: Highlight the existing gaps, limitations, or unresolved aspects within the current body of literature related to the research problem.
• The research relevance: Explain why the chosen research problem and its subsequent investigation through a literature review are significant and relevant in your academic field.
• The literature review method: If applicable, describe the methodology employed in your literature review, especially if it is a systematic review or follows a specific research framework.
• The main findings or insights of the literature review: Summarize the key discoveries, insights, or trends that have emerged from your comprehensive review of the literature.
• The main argument of the literature review: Conclude the introduction by outlining the primary argument or statement that your literature review will substantiate, linking it to the research problem and relevance you’ve established.
• Preview of the literature review’s structure: Offer a glimpse into the organization of the literature review paper, acting as a guide for the reader. This overview outlines the subsequent sections of the paper and provides an understanding of what to anticipate.

By addressing these elements, your introduction will provide a clear and structured overview of what readers can expect in your literature review paper.

Regular literature review section in an academic article or essay

Most academic articles or essays incorporate regular literature review sections, often placed after the introduction. These sections serve to establish a scholarly basis for the research or discussion within the paper.

In a standard 8000-word journal article, the literature review section typically spans between 750 and 1250 words. The first few sentences or the first paragraph within this section often serve as an introduction. It should encompass:

• An introduction to the topic: When delving into the academic literature on a specific topic, it’s important to provide a smooth transition that aids the reader in comprehending why certain aspects will be discussed within your literature review.
• The core argument: While literature review sections primarily synthesize the work of other scholars, they should consistently connect to your central argument. This central argument serves as the crux of your message or the key takeaway you want your readers to retain. By positioning it at the outset of the literature review section and systematically substantiating it with evidence, you not only enhance reader comprehension but also elevate overall readability. This primary argument can typically be distilled into 1-2 succinct sentences.

In some cases, you might include:

• Methodology: Details about the methodology used, but only if your literature review employed a specialized method. If your approach involved a broader overview without a systematic methodology, you can omit this section, thereby conserving word count.

By addressing these elements, your introduction will effectively integrate your literature review into the broader context of your academic paper or essay. This will, in turn, assist your reader in seamlessly following your overarching line of argumentation.

Introduction to a literature review chapter in thesis or dissertation

The literature review typically constitutes a distinct chapter within a thesis or dissertation. Often, it is Chapter 2 of a thesis or dissertation.

Some students choose to incorporate a brief introductory section at the beginning of each chapter, including the literature review chapter. Alternatively, others opt to seamlessly integrate the introduction into the initial sentences of the literature review itself. Both approaches are acceptable, provided that you incorporate the following elements:

• Purpose of the literature review and its relevance to the thesis/dissertation research: Explain the broader objectives of the literature review within the context of your research and how it contributes to your thesis or dissertation. Essentially, you’re telling the reader why this literature review is important and how it fits into the larger scope of your academic work.
• Primary argument: Succinctly communicate what you aim to prove, explain, or explore through the review of existing literature. This statement helps guide the reader’s understanding of the review’s purpose and what to expect from it.
• Preview of the literature review’s content: Provide a brief overview of the topics or themes that your literature review will cover. It’s like a roadmap for the reader, outlining the main areas of focus within the review. This preview can help the reader anticipate the structure and organization of your literature review.
• Methodology: If your literature review involved a specific research method, such as a systematic review or meta-analysis, you should briefly describe that methodology. However, this is not always necessary, especially if your literature review is more of a narrative synthesis without a distinct research method.

By addressing these elements, your introduction will empower your literature review to play a pivotal role in your thesis or dissertation research. It will accomplish this by integrating your research into the broader academic literature and providing a solid theoretical foundation for your work.

Comprehending the art of crafting your own literature review introduction becomes significantly more accessible when you have concrete examples to examine. Here, you will find several examples that meet, or in most cases, adhere to the criteria described earlier.

Example 1: An effective introduction for an academic literature review paper

To begin, let’s delve into the introduction of an academic literature review paper. We will examine the paper “How does culture influence innovation? A systematic literature review”, which was published in 2018 in the journal Management Decision.

The entire introduction spans 611 words and is divided into five paragraphs. In this introduction, the authors accomplish the following:

• In the first paragraph, the authors introduce the broader topic of the literature review, which focuses on innovation and its significance in the context of economic competition. They underscore the importance of this topic, highlighting its relevance for both researchers and policymakers.
• In the second paragraph, the authors narrow down their focus to emphasize the specific role of culture in relation to innovation.
• In the third paragraph, the authors identify research gaps, noting that existing studies are often fragmented and disconnected. They then emphasize the value of conducting a systematic literature review to enhance our understanding of the topic.
• In the fourth paragraph, the authors introduce their specific objectives and explain how their insights can benefit other researchers and business practitioners.
• In the fifth and final paragraph, the authors provide an overview of the paper’s organization and structure.

In summary, this introduction stands as a solid example. While the authors deviate from previewing their key findings (which is a common practice at least in the social sciences), they do effectively cover all the other previously mentioned points.

Example 2: An effective introduction to a literature review section in an academic paper

The second example represents a typical academic paper, encompassing not only a literature review section but also empirical data, a case study, and other elements. We will closely examine the introduction to the literature review section in the paper “The environmentalism of the subalterns: a case study of environmental activism in Eastern Kurdistan/Rojhelat”, which was published in 2021 in the journal Local Environment.

The paper begins with a general introduction and then proceeds to the literature review, designated by the authors as their conceptual framework. Of particular interest is the first paragraph of this conceptual framework, comprising 142 words across five sentences:

“ A peripheral and marginalised nationality within a multinational though-Persian dominated Iranian society, the Kurdish people of Iranian Kurdistan (a region referred by the Kurds as Rojhelat/Eastern Kurdi-stan) have since the early twentieth century been subject to multifaceted and systematic discriminatory and exclusionary state policy in Iran. This condition has left a population of 12–15 million Kurds in Iran suffering from structural inequalities, disenfranchisement and deprivation. Mismanagement of Kurdistan’s natural resources and the degradation of its natural environmental are among examples of this disenfranchisement. As asserted by Julian Agyeman (2005), structural inequalities that sustain the domination of political and economic elites often simultaneously result in environmental degradation, injustice and discrimination against subaltern communities. This study argues that the environmental struggle in Eastern Kurdistan can be asserted as a (sub)element of the Kurdish liberation movement in Iran. Conceptually this research is inspired by and has been conducted through the lens of ‘subalternity’ ” ( Hassaniyan, 2021, p. 931 ).

In this first paragraph, the author is doing the following:

• The author contextualises the research
• The author links the research focus to the international literature on structural inequalities
• The author clearly presents the argument of the research
• The author clarifies how the research is inspired by and uses the concept of ‘subalternity’.

Thus, the author successfully introduces the literature review, from which point onward it dives into the main concept (‘subalternity’) of the research, and reviews the literature on socio-economic justice and environmental degradation.

While introductions to a literature review section aren’t always required to offer the same level of study context detail as demonstrated here, this introduction serves as a commendable model for orienting the reader within the literature review. It effectively underscores the literature review’s significance within the context of the study being conducted.

Examples 3-5: Effective introductions to literature review chapters

The introduction to a literature review chapter can vary in length, depending largely on the overall length of the literature review chapter itself. For example, a master’s thesis typically features a more concise literature review, thus necessitating a shorter introduction. In contrast, a Ph.D. thesis, with its more extensive literature review, often includes a more detailed introduction.

Numerous universities offer online repositories where you can access theses and dissertations from previous years, serving as valuable sources of reference. Many of these repositories, however, may require you to log in through your university account. Nevertheless, a few open-access repositories are accessible to anyone, such as the one by the University of Manchester . It’s important to note though that copyright restrictions apply to these resources, just as they would with published papers.

Master’s thesis literature review introduction

The first example is “Benchmarking Asymmetrical Heating Models of Spider Pulsar Companions” by P. Sun, a master’s thesis completed at the University of Manchester on January 9, 2024. The author, P. Sun, introduces the literature review chapter very briefly but effectively:

PhD thesis literature review chapter introduction

The second example is Deep Learning on Semi-Structured Data and its Applications to Video-Game AI, Woof, W. (Author). 31 Dec 2020, a PhD thesis completed at the University of Manchester . In Chapter 2, the author offers a comprehensive introduction to the topic in four paragraphs, with the final paragraph serving as an overview of the chapter’s structure:

PhD thesis literature review introduction

The last example is the doctoral thesis Metacognitive strategies and beliefs: Child correlates and early experiences Chan, K. Y. M. (Author). 31 Dec 2020 . The author clearly conducted a systematic literature review, commencing the review section with a discussion of the methodology and approach employed in locating and analyzing the selected records.

Having absorbed all of this information, let’s recap the essential steps and offer a succinct guide on how to proceed with creating your literature review introduction:

• Contextualize your review : Begin by clearly identifying the academic context in which your literature review resides and determining the necessary information to include.
• Outline your structure : Develop a structured outline for your literature review, highlighting the essential information you plan to incorporate in your introduction.
• Literature review process : Conduct a rigorous literature review, reviewing and analyzing relevant sources.
• Summarize and abstract : After completing the review, synthesize the findings and abstract key insights, trends, and knowledge gaps from the literature.
• Craft the introduction : Write your literature review introduction with meticulous attention to the seamless integration of your review into the larger context of your work. Ensure that your introduction effectively elucidates your rationale for the chosen review topics and the underlying reasons guiding your selection.

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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.

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

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

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

What are Literature Reviews?

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

Goals of Literature Reviews

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

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

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

What kinds of sources require a Literature Review?

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

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

Types of Literature Reviews

What kinds of literature reviews are written?

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

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

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

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

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

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

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

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

Literature Reviews in the Health Sciences

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

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

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

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

What is a literature review? A literature review is a survey of scholarly sources on a specific topic. It provides an overview of current knowledge, allowing you to identify relevant theories, methods, and gaps in the existing research.

There are five key steps to writing a literature review:

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

A good literature review doesn’t just summarise sources – it analyses, synthesises, and critically evaluates to give a clear picture of the state of knowledge on the subject.

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Table of contents

Why write a literature review, examples of literature reviews, step 1: search for relevant literature, step 2: evaluate and select sources, step 3: identify themes, debates and gaps, step 4: outline your literature review’s structure, step 5: write your literature review, frequently asked questions about literature reviews, introduction.

• Quick Run-through
• Step 1 & 2

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

• Demonstrate your familiarity with the topic and scholarly context
• Develop a theoretical framework and methodology for your research
• Position yourself in relation to other researchers and theorists
• Show how your dissertation addresses a gap or contributes to a debate

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

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

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

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

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

Download Word doc Download Google doc

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

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

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

Make a list of keywords

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

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

Search for relevant sources

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

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

You can use boolean operators to help narrow down your search:

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

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

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

For each publication, ask yourself:

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

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

You can find out how many times an article has been cited on Google Scholar – a high citation count means the article has been influential in the field, and should certainly be included in your literature review.

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

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

Take notes and cite your sources

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

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

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

Prevent plagiarism, run a free check.

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

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

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

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

There are various approaches to organising the body of a literature review. You should have a rough idea of your strategy before you start writing.

Depending on the length of your literature review, you can combine several of these strategies (for example, your overall structure might be thematic, but each theme is discussed chronologically).

Chronological

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

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

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

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

Methodological

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

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

Theoretical

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

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

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

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

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

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

As you write, make sure to follow these tips:

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

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

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

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

It is often written as part of a dissertation , thesis, research paper , or proposal .

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

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

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

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

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How To Write A Literature Review - A Complete Guide

Table of Contents

A literature review is much more than just another section in your research paper. It forms the very foundation of your research. It is a formal piece of writing where you analyze the existing theoretical framework, principles, and assumptions and use that as a base to shape your approach to the research question.

Curating and drafting a solid literature review section not only lends more credibility to your research paper but also makes your research tighter and better focused. But, writing literature reviews is a difficult task. It requires extensive reading, plus you have to consider market trends and technological and political changes, which tend to change in the blink of an eye.

Now streamline your literature review process with the help of SciSpace Copilot. With this AI research assistant, you can efficiently synthesize and analyze a vast amount of information, identify key themes and trends, and uncover gaps in the existing research. Get real-time explanations, summaries, and answers to your questions for the paper you're reviewing, making navigating and understanding the complex literature landscape easier.

In this comprehensive guide, we will explore everything from the definition of a literature review, its appropriate length, various types of literature reviews, and how to write one.

What is a literature review?

A literature review is a collation of survey, research, critical evaluation, and assessment of the existing literature in a preferred domain.

Eminent researcher and academic Arlene Fink, in her book Conducting Research Literature Reviews , defines it as the following:

“A literature review surveys books, scholarly articles, and any other sources relevant to a particular issue, area of research, or theory, and by so doing, provides a description, summary, and critical evaluation of these works in relation to the research problem being investigated.

Literature reviews are designed to provide an overview of sources you have explored while researching a particular topic, and to demonstrate to your readers how your research fits within a larger field of study.”

Simply put, a literature review can be defined as a critical discussion of relevant pre-existing research around your research question and carving out a definitive place for your study in the existing body of knowledge. Literature reviews can be presented in multiple ways: a section of an article, the whole research paper itself, or a chapter of your thesis.

A literature review does function as a summary of sources, but it also allows you to analyze further, interpret, and examine the stated theories, methods, viewpoints, and, of course, the gaps in the existing content.

As an author, you can discuss and interpret the research question and its various aspects and debate your adopted methods to support the claim.

What is the purpose of a literature review?

A literature review is meant to help your readers understand the relevance of your research question and where it fits within the existing body of knowledge. As a researcher, you should use it to set the context, build your argument, and establish the need for your study.

What is the importance of a literature review?

The literature review is a critical part of research papers because it helps you:

• Gain an in-depth understanding of your research question and the surrounding area
• Convey that you have a thorough understanding of your research area and are up-to-date with the latest changes and advancements
• Establish how your research is connected or builds on the existing body of knowledge and how it could contribute to further research
• Elaborate on the validity and suitability of your theoretical framework and research methodology
• Identify and highlight gaps and shortcomings in the existing body of knowledge and how things need to change
• Convey to readers how your study is different or how it contributes to the research area

How long should a literature review be?

Ideally, the literature review should take up 15%-40% of the total length of your manuscript. So, if you have a 10,000-word research paper, the minimum word count could be 1500.

Your literature review format depends heavily on the kind of manuscript you are writing — an entire chapter in case of doctoral theses, a part of the introductory section in a research article, to a full-fledged review article that examines the previously published research on a topic.

Another determining factor is the type of research you are doing. The literature review section tends to be longer for secondary research projects than primary research projects.

What are the different types of literature reviews?

All literature reviews are not the same. There are a variety of possible approaches that you can take. It all depends on the type of research you are pursuing.

Here are the different types of literature reviews:

Argumentative review

It is called an argumentative review when you carefully present literature that only supports or counters a specific argument or premise to establish a viewpoint.

Integrative review

It is a type of literature review focused on building a comprehensive understanding of a topic by combining available theoretical frameworks and empirical evidence.

Methodological review

This approach delves into the ''how'' and the ''what" of the research question —  you cannot look at the outcome in isolation; you should also review the methodology used.

Systematic review

This form consists of an overview of existing evidence pertinent to a clearly formulated research question, which uses pre-specified and standardized methods to identify and critically appraise relevant research and collect, report, and analyze data from the studies included in the review.

Meta-analysis review

Meta-analysis uses statistical methods to summarize the results of independent studies. By combining information from all relevant studies, meta-analysis can provide more precise estimates of the effects than those derived from the individual studies included within a review.

Historical review

Historical literature reviews focus on examining research throughout a period, often starting with the first time an issue, concept, theory, or phenomenon emerged in the literature, then tracing its evolution within the scholarship of a discipline. The purpose is to place research in a historical context to show familiarity with state-of-the-art developments and identify future research's likely directions.

Theoretical Review

This form aims to examine the corpus of theory accumulated regarding an issue, concept, theory, and phenomenon. The theoretical literature review helps to establish what theories exist, the relationships between them, the degree the existing approaches have been investigated, and to develop new hypotheses to be tested.

Scoping Review

The Scoping Review is often used at the beginning of an article, dissertation, or research proposal. It is conducted before the research to highlight gaps in the existing body of knowledge and explains why the project should be greenlit.

State-of-the-Art Review

The State-of-the-Art review is conducted periodically, focusing on the most recent research. It describes what is currently known, understood, or agreed upon regarding the research topic and highlights where there are still disagreements.

Can you use the first person in a literature review?

When writing literature reviews, you should avoid the usage of first-person pronouns. It means that instead of "I argue that" or "we argue that," the appropriate expression would be "this research paper argues that."

Do you need an abstract for a literature review?

Ideally, yes. It is always good to have a condensed summary that is self-contained and independent of the rest of your review. As for how to draft one, you can follow the same fundamental idea when preparing an abstract for a literature review. It should also include:

• The research topic and your motivation behind selecting it
• A one-sentence thesis statement
• An explanation of the kinds of literature featured in the review
• Summary of what you've learned
• Conclusions you drew from the literature you reviewed
• Potential implications and future scope for research

Here's an example of the abstract of a literature review

Is a literature review written in the past tense?

Yes, the literature review should ideally be written in the past tense. You should not use the present or future tense when writing one. The exceptions are when you have statements describing events that happened earlier than the literature you are reviewing or events that are currently occurring; then, you can use the past perfect or present perfect tenses.

How many sources for a literature review?

There are multiple approaches to deciding how many sources to include in a literature review section. The first approach would be to look level you are at as a researcher. For instance, a doctoral thesis might need 60+ sources. In contrast, you might only need to refer to 5-15 sources at the undergraduate level.

The second approach is based on the kind of literature review you are doing — whether it is merely a chapter of your paper or if it is a self-contained paper in itself. When it is just a chapter, sources should equal the total number of pages in your article's body. In the second scenario, you need at least three times as many sources as there are pages in your work.

Quick tips on how to write a literature review

To know how to write a literature review, you must clearly understand its impact and role in establishing your work as substantive research material.

You need to follow the below-mentioned steps, to write a literature review:

• Outline the purpose behind the literature review
• Search relevant literature
• Examine and assess the relevant resources
• Discover connections by drawing deep insights from the resources
• Structure planning to write a good literature review

1. Outline and identify the purpose of  a literature review

As a first step on how to write a literature review, you must know what the research question or topic is and what shape you want your literature review to take. Ensure you understand the research topic inside out, or else seek clarifications. You must be able to the answer below questions before you start:

• How many sources do I need to include?
• What kind of sources should I analyze?
• How much should I critically evaluate each source?
• Should I summarize, synthesize or offer a critique of the sources?
• Do I need to include any background information or definitions?

Additionally, you should know that the narrower your research topic is, the swifter it will be for you to restrict the number of sources to be analyzed.

2. Search relevant literature

Dig deeper into search engines to discover what has already been published around your chosen topic. Make sure you thoroughly go through appropriate reference sources like books, reports, journal articles, government docs, and web-based resources.

You must prepare a list of keywords and their different variations. You can start your search from any library’s catalog, provided you are an active member of that institution. The exact keywords can be extended to widen your research over other databases and academic search engines like:

• Google Scholar
• Microsoft Academic
• Science.gov

Besides, it is not advisable to go through every resource word by word. Alternatively, what you can do is you can start by reading the abstract and then decide whether that source is relevant to your research or not.

Additionally, you must spend surplus time assessing the quality and relevance of resources. It would help if you tried preparing a list of citations to ensure that there lies no repetition of authors, publications, or articles in the literature review.

3. Examine and assess the sources

It is nearly impossible for you to go through every detail in the research article. So rather than trying to fetch every detail, you have to analyze and decide which research sources resemble closest and appear relevant to your chosen domain.

While analyzing the sources, you should look to find out answers to questions like:

• What question or problem has the author been describing and debating?
• What is the definition of critical aspects?
• How well the theories, approach, and methodology have been explained?
• Whether the research theory used some conventional or new innovative approach?
• How relevant are the key findings of the work?
• In what ways does it relate to other sources on the same topic?
• What challenges does this research paper pose to the existing theory
• What are the possible contributions or benefits it adds to the subject domain?

Be always mindful that you refer only to credible and authentic resources. It would be best if you always take references from different publications to validate your theory.

Always keep track of important information or data you can present in your literature review right from the beginning. It will help steer your path from any threats of plagiarism and also make it easier to curate an annotated bibliography or reference section.

4. Discover connections

At this stage, you must start deciding on the argument and structure of your literature review. To accomplish this, you must discover and identify the relations and connections between various resources while drafting your abstract.

A few aspects that you should be aware of while writing a literature review include:

• Rise to prominence: Theories and methods that have gained reputation and supporters over time.
• Constant scrutiny: Concepts or theories that repeatedly went under examination.
• Contradictions and conflicts: Theories, both the supporting and the contradictory ones, for the research topic.
• Knowledge gaps: What exactly does it fail to address, and how to bridge them with further research?
• Influential resources: Significant research projects available that have been upheld as milestones or perhaps, something that can modify the current trends

Once you join the dots between various past research works, it will be easier for you to draw a conclusion and identify your contribution to the existing knowledge base.

5. Structure planning to write a good literature review

There exist different ways towards planning and executing the structure of a literature review. The format of a literature review varies and depends upon the length of the research.

Like any other research paper, the literature review format must contain three sections: introduction, body, and conclusion. The goals and objectives of the research question determine what goes inside these three sections.

Nevertheless, a good literature review can be structured according to the chronological, thematic, methodological, or theoretical framework approach.

Literature review samples

1. Standalone

2. As a section of a research paper

How SciSpace Discover makes literature review a breeze?

SciSpace Discover is a one-stop solution to do an effective literature search and get barrier-free access to scientific knowledge. It is an excellent repository where you can find millions of only peer-reviewed articles and full-text PDF files. Here’s more on how you can use it:

Find the right information

Find what you want quickly and easily with comprehensive search filters that let you narrow down papers according to PDF availability, year of publishing, document type, and affiliated institution. Moreover, you can sort the results based on the publishing date, citation count, and relevance.

Assess credibility of papers quickly

When doing the literature review, it is critical to establish the quality of your sources. They form the foundation of your research. SciSpace Discover helps you assess the quality of a source by providing an overview of its references, citations, and performance metrics.

Get the complete picture in no time

SciSpace Discover’s personalized suggestion engine helps you stay on course and get the complete picture of the topic from one place. Every time you visit an article page, it provides you links to related papers. Besides that, it helps you understand what’s trending, who are the top authors, and who are the leading publishers on a topic.

Make referring sources super easy

To ensure you don't lose track of your sources, you must start noting down your references when doing the literature review. SciSpace Discover makes this step effortless. Click the 'cite' button on an article page, and you will receive preloaded citation text in multiple styles — all you've to do is copy-paste it into your manuscript.

Final tips on how to write a literature review

A massive chunk of time and effort is required to write a good literature review. But, if you go about it systematically, you'll be able to save a ton of time and build a solid foundation for your research.

We hope this guide has helped you answer several key questions you have about writing literature reviews.

Would you like to explore SciSpace Discover and kick off your literature search right away? You can get started here .

Frequently Asked Questions (FAQs)

1. how to start a literature review.

• What questions do you want to answer?

• What sources do you need to answer these questions?

• What information do these sources contain?

• How can you use this information to answer your questions?

2. What to include in a literature review?

• A brief background of the problem or issue

• What has previously been done to address the problem or issue

• A description of what you will do in your project

• How this study will contribute to research on the subject

3. Why literature review is important?

The literature review is an important part of any research project because it allows the writer to look at previous studies on a topic and determine existing gaps in the literature, as well as what has already been done. It will also help them to choose the most appropriate method for their own study.

4. How to cite a literature review in APA format?

To cite a literature review in APA style, you need to provide the author's name, the title of the article, and the year of publication. For example: Patel, A. B., & Stokes, G. S. (2012). The relationship between personality and intelligence: A meta-analysis of longitudinal research. Personality and Individual Differences, 53(1), 16-21

5. What are the components of a literature review?

• A brief introduction to the topic, including its background and context. The introduction should also include a rationale for why the study is being conducted and what it will accomplish.

• A description of the methodologies used in the study. This can include information about data collection methods, sample size, and statistical analyses.

• A presentation of the findings in an organized format that helps readers follow along with the author's conclusions.

6. What are common errors in writing literature review?

• Not spending enough time to critically evaluate the relevance of resources, observations and conclusions.

• Totally relying on secondary data while ignoring primary data.

• Letting your personal bias seep into your interpretation of existing literature.

• No detailed explanation of the procedure to discover and identify an appropriate literature review.

7. What are the 5 C's of writing literature review?

• Cite - the sources you utilized and referenced in your research.

• Compare - existing arguments, hypotheses, methodologies, and conclusions found in the knowledge base.

• Contrast - the arguments, topics, methodologies, approaches, and disputes that may be found in the literature.

• Critique - the literature and describe the ideas and opinions you find more convincing and why.

• Connect - the various studies you reviewed in your research.

8. How many sources should a literature review have?

When it is just a chapter, sources should equal the total number of pages in your article's body. if it is a self-contained paper in itself, you need at least three times as many sources as there are pages in your work.

9. Can literature review have diagrams?

• To represent an abstract idea or concept

• To explain the steps of a process or procedure

• To help readers understand the relationships between different concepts

10. How old should sources be in a literature review?

Sources for a literature review should be as current as possible or not older than ten years. The only exception to this rule is if you are reviewing a historical topic and need to use older sources.

11. What are the types of literature review?

• Argumentative review

• Integrative review

• Methodological review

• Systematic review

• Meta-analysis review

• Historical review

• Theoretical review

• Scoping review

• State-of-the-Art review

12. Is a literature review mandatory?

Yes. Literature review is a mandatory part of any research project. It is a critical step in the process that allows you to establish the scope of your research, and provide a background for the rest of your work.

But before you go,

• Six Online Tools for Easy Literature Review
• Evaluating literature review: systematic vs. scoping reviews
• Systematic Approaches to a Successful Literature Review
• Writing Integrative Literature Reviews: Guidelines and Examples

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How to Do a Literature Review: Introduction

• Introduction
• Where to Begin
• Organization & Writing

What Is a Literature Review?

A literature review looks at key published material (scholarly articles, books, pamphlets, etc.) on a particular issue, area of research, or theory and provides not only a summary of the source, but also a critical evaluation.  Each source is summarized, synthesized, and often evaluated.  More than a mere summary of the sources, it highlights what is and is not known, identifies controversy surrounding a topic, formulates questions that need further research, linking the known literature to how your research adds to the larger field of study.

A literature review can be part of a larger research project in which the researcher presents a proposal, plan of action, or primary research work (a survey, interviews); or, it can stand alone as an analysis of what the experts say on a given issue or area. 

For a quick overview, watch this excellent video: What is a Literature Review?  by Steely Libraries NKU.

Types of Literature Reviews

Systematic reviews  are literature reviews structured by an explicit purpose and a set of specific parameters regarding the sources reviewed.  They contain:

• a specific problem for which the review is being performed
• one or more research purposes/questions targeting that problem
• the sources of research that will be reviewed
• specifics on the search process
• specific metrics for selecting sources
• techniques used to evaluate the sources
• techniques used to analyze and synthesize the findings in the sources

Meta-analyses:  Systematic reviews which use a quantitative way of statistically summarizing and comparing the results of the studies reviewed.

Argumentative Review :  Literature reviews that support or oppose an argument, assumption, or problem established within the literature

Integrative Review : A review that synthesizes the literature such that new perspectives on the topic are introduced.

Historical Review : Looks at research throughout a time period, examining trends, evolution, developments--often pointing to future direction for research.

Methodological Review : Reviews the method of analyses used in studies--can highlight problems, ethical issues to be aware of in research to be conducted.

Theoretical Review : Looks at theories surrounding a concept/issue/phenomena establishing current thinking, degree of investigation regarding the theories, relationships between them, shortcomings, or emerging research problems unanswered by current theories.

Why Create a Literature Review?

A literature review:

• provides an overview of established knowledge and ideas directly related to and organized around a specific research question
• provides professionals with a guide to the literature
• provides context and background for a research question
• provides credibility for the author's knowledge of the field
• helps to establish underpinnings behind the research are factual
• helps identify previous areas of scholarship to prevent duplication of research

How Is a Literature Review Different from an Annotated Bibliography?

Literature reviews and annotated bibliographies are close cousins, but there are many differences between the two.

This short video gives an excellent account of what an annotated bibliography involves: What's an Annotated Bibliography , Brock University Library.

They have in common that they both focus primarily on published materials, usually scholarly, that present a range of perspectives on a specific topic.

They differ as follows:

Note: Both the literature review and the annotated bibliography are excellent tools for getting the most out of your research. For this reason, your professor may sometimes ask you to complete the literature review section of your Constructive Action (CA) project as an annotated bibliography.

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How to write a superb literature review

Andy Tay is a freelance writer based in Singapore.

You can also search for this author in PubMed   Google Scholar

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

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

Interviews have been edited for length and clarity.

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

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

Article   Google Scholar  

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

Article   PubMed   Google Scholar  

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

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

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Writing a literature review

Find out how to write a lit review.

What is a literature review ?

A literature review explores and evaluates the literature on a specific topic or question. It synthesises the contributions of the different authors, often to identify areas that need further exploration.

You may be required to write a literature review as a standalone document or part of a larger body of research, such as a thesis.

• The point of a standalone literature review is to demonstrate that you have read widely in your field and you understand the main arguments.
• As part of a thesis or research paper, the literature review defines your project by establishing how your work will extend or differ from previous work and what contribution it will make.

What are markers looking for?

In the best literature reviews, the writer:

• Has a clear understanding of key concepts within the topic.
• Clarifies important definitions and terminology.
• Covers the breadth of the specific topic.
• Critically discusses the ideas in the literature and evaluates how authors present them.
• Clearly indicates a research gap for future enquiry.

How do I write a literature review?

This video outlines a step by step approach to help you evaluate readings, organise ideas and write critically. It provides examples of how to connect, interpret and critique ideas to make sure your voice comes through strongly.

Tips for research, reading and writing

You may be given a specific question to research or broad topics which must be refined to a question that can be reasonably addressed in the time and word limit available.

Use your early reading to help you determine and refine your topic.

• Too much literature? You probably need to narrow your scope. Try to identify a more specific issue of interest.
• Not enough literature? Your topic may be too specific and needs to be broader.

Start with readings suggested by your lecturers or supervisors. Then, do your own research - the best place to go is the Library Website .

You can also use the Library Guides or speak to a librarian to identify the most useful databases for you and to learn how to search for sources effectively and efficiently.

Cover the field

Make sure your literature search covers a broad range of views and information relevant to your topic. Focussing on a narrow selection of sources may result in a lack of depth. You are not expected to cover all research and scholarly opinions on your topic, but you need to identify and include important viewpoints. A quality literature review examines and evaluates different viewpoints based on the evidence presented, rather than providing only material that reinforces a bias.

Use reading strategies

Survey, skim and scan to find the most relevant articles, and the most relevant parts of those articles. These can be re-read more closely later when you have acquired an overview of your topic.

Take notes as you read

This helps to organise and develop your thoughts. Record your own reactions to the text in your notes, perhaps in a separate column. These notes can form the basis of your critical evaluation of the text. Record any facts, opinions or direct quotes that are likely to be useful to your review, noting the page numbers, author and year.

Stop reading when you have enough

This depends on the word count required of this literature review. A review of one thousand words can only cover the major ideas and probably less than ten references. Longer reviews that form part of a large research paper will include more than fifty. Your tutor or supervisor should be able to suggest a suitable number.

As you read, ask yourself these questions:

• Have I answered my question without any obvious gaps?
• Have I read this before? Are there any new related issues coming up as I search the literature?
• Have I found multiple references which cover the same material or just enough to prove agreement?

There are many possible ways to organise the material. For example:

• chronologically
• by theoretical perspective
• from most to least important
• by issue or theme

It is important to remember that you are not merely cataloguing or describing the literature you read. Therefore, you need to choose an organisation that will enable you to compare the various authors' treatment of ideas. This is often best achieved by organising thematically, or grouping ideas into sets of common issues tackled in the various texts. These themes will form the basis of the different threads that are the focus of your study.

A standalone literature review

A standalone literature review is structured much like an academic essay.

• Introduction - establish the context for your topic and outline your main contentions about the literature
• Main body - explain and support these inferences in the main body
• Conclusion - summarise your main points and restate the contention.

The main difference between an essay and this kind of literature review is that an essay focuses on a topic and uses the literature as a support for the arguments. In a standalone literature review, the literature itself is the topic of discussion and evaluation. This means you evaluate and discuss not only the informational content but the quality of the author’s handling of the content.

A literature review as part of a larger research paper?

As part of a larger research paper, the literature review may take many forms, depending on your discipline, your topic and the logic of your research. Traditionally, in empirical research, the literature review is included in the introduction, or a standalone chapter immediately following the introduction. For other forms of research, you may need to engage more extensively with the literature and thus, the literature review may spread over more than one chapter, or even be distributed throughout the thesis.

Start writing early. Writing will clarify your thinking on the topic and reveal any gaps in information and logic. If your ideas change, sections and paragraphs can be reworked to change your contentions or include extra information.

Similarly, draft an overall plan for your review as soon as you are ready, but be prepared to rework sections of it to reflect your developing argument.

The most important thing to remember is that you are writing a review . That means you must move past describing what other authors have written by connecting, interpreting and critiquing their ideas and presenting your own analysis and interpretation.

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

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

Table of Contents

• What is the purpose of literature review? 
• a. Habitat Loss and Species Extinction: 
• b. Range Shifts and Phenological Changes: 
• c. Ocean Acidification and Coral Reefs: 
• d. Adaptive Strategies and Conservation Efforts: 
• How to write a good literature review 
• Choose a Topic and Define the Research Question: 
• Decide on the Scope of Your Review: 
• Select Databases for Searches: 
• Conduct Searches and Keep Track: 
• Review the Literature: 
• Organize and Write Your Literature Review: 
• Frequently asked questions 

What is a literature review?

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

What is the purpose of literature review?

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

• Contextualizing the Research Problem: The literature review provides a background and context for the research problem under investigation. It helps to situate the study within the existing body of knowledge. 
• Identifying Gaps in Knowledge: By identifying gaps, contradictions, or areas requiring further research, the researcher can shape the research question and justify the significance of the study. This is crucial for ensuring that the new research contributes something novel to the field. 
• Understanding Theoretical and Conceptual Frameworks: Literature reviews help researchers gain an understanding of the theoretical and conceptual frameworks used in previous studies. This aids in the development of a theoretical framework for the current research. 
• Providing Methodological Insights: Another purpose of literature reviews is that it allows researchers to learn about the methodologies employed in previous studies. This can help in choosing appropriate research methods for the current study and avoiding pitfalls that others may have encountered. 
• Establishing Credibility: A well-conducted literature review demonstrates the researcher’s familiarity with existing scholarship, establishing their credibility and expertise in the field. It also helps in building a solid foundation for the new research. 
• Informing Hypotheses or Research Questions: The literature review guides the formulation of hypotheses or research questions by highlighting relevant findings and areas of uncertainty in existing literature. 

Literature review example

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

Literature Review on Climate Change Impacts on Biodiversity:

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

a. Habitat Loss and Species Extinction:

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

b. Range Shifts and Phenological Changes:

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

c. Ocean Acidification and Coral Reefs:

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

d. Adaptive Strategies and Conservation Efforts:

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

How to write a good literature review

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

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

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

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

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

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

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

Conducting a literature review

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

Choose a Topic and Define the Research Question:

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

Decide on the Scope of Your Review:

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

Select Databases for Searches:

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

Conduct Searches and Keep Track:

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

Review the Literature:

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

Organize and Write Your Literature Review:

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

The literature review sample and detailed advice on writing and conducting a review will help you produce a well-structured report. But remember that a literature review is an ongoing process, and it may be necessary to revisit and update it as your research progresses. 

Frequently asked questions

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

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

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

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

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

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

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

References 

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

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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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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 .

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27 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

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Literature Reviews

Introduction, who & what type, the literature review process, why do you need to do a literature review.

• Define a topic
• Identify keywords
• More search tips
• Understand & Analyse
• More resources
• Accessing help
• Systematic Style Reviews Guide

The A-Z of literature reviews

©  Produced by the University of Manchester

Writing the Literature Review (Part 1)

Note: You can access Parts 2 and 3 of this series from the end of this video.

A literature review is a piece of writing that describes, summarises and evaluates existing information on your topic. It is a critical analysis of the strengths and weaknesses and the theoretical basis of current knowledge.

The literature review highlights relationships, or lack thereof, between resources and helps you identify gaps within the literature. It is designed to find out how much we know about a particular topic according to the research that has been conducted so far.

This guide will assist undergraduate and postgraduate students and researchers with completing this process.

Undergraduate students

Need to do a standalone  literature review which is a single assessment piece. It is used to explore a topic in detail and depth.

Postgraduate students & researchers

Need to do a literature review as  part of a larger body of work  which may be included in theses and dissertations, research articles or research proposals. It is usually used as the justification to support the need for you to do your research and outline the overarching theoretical framework you will use.

• View some example literature reviews
• Defining your topic
• Searching the literature

• Organising resources
• Understanding and analysing resources
• Synthesising resources
• Writing your review

The reasons or purpose(s) for doing literature reviews is to: 

• Next: Define a topic >>
• Last Updated: Apr 26, 2024 10:38 AM
• URL: https://libguides.jcu.edu.au/litreview

How do I Write a Literature Review?: #5 Writing the Review

• Step #1: Choosing a Topic
• Step #2: Finding Information
• Step #3: Evaluating Content
• Step #4: Synthesizing Content
• #5 Writing the Review
• Citing Your Sources

WRITING THE REVIEW 

You've done the research and now you're ready to put your findings down on paper. When preparing to write your review, first consider how will you organize your review.

The actual review generally has 5 components:

Abstract  -  An abstract is a summary of your literature review. It is made up of the following parts:

• A contextual sentence about your motivation behind your research topic
• Your thesis statement
• A descriptive statement about the types of literature used in the review
• Summarize your findings
• Conclusion(s) based upon your findings

Introduction :   Like a typical research paper introduction, provide the reader with a quick idea of the topic of the literature review:

• Define or identify the general topic, issue, or area of concern. This provides the reader with context for reviewing the literature.
• Identify related trends in what has already been published about the topic; or conflicts in theory, methodology, evidence, and conclusions; or gaps in research and scholarship; or a single problem or new perspective of immediate interest.
• Establish your reason (point of view) for reviewing the literature; explain the criteria to be used in analyzing and comparing literature and the organization of the review (sequence); and, when necessary, state why certain literature is or is not included (scope)  - 

Body :  The body of a literature review contains your discussion of sources and can be organized in 3 ways-

• Chronological -  by publication or by trend
• Thematic -  organized around a topic or issue, rather than the progression of time
• Methodical -  the focusing factor usually does not have to do with the content of the material. Instead, it focuses on the "methods" of the literature's researcher or writer that you are reviewing

You may also want to include a section on "questions for further research" and discuss what questions the review has sparked about the topic/field or offer suggestions for future studies/examinations that build on your current findings.

Conclusion :  In the conclusion, you should:

Conclude your paper by providing your reader with some perspective on the relationship between your literature review's specific topic and how it's related to it's parent discipline, scientific endeavor, or profession.

Bibliography :   Since a literature review is composed of pieces of research, it is very important that your correctly cite the literature you are reviewing, both in the reviews body as well as in a bibliography/works cited. To learn more about different citation styles, visit the " Citing Your Sources " tab.

• Writing a Literature Review: Wesleyan University
• Literature Review: Edith Cowan University
• << Previous: Step #4: Synthesizing Content
• Next: Citing Your Sources >>
• Last Updated: Aug 22, 2023 1:35 PM
• URL: https://libguides.eastern.edu/literature_reviews

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Literature Reviews

Introduction

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Critical reading, writing your review, citing and referencing.

• Further assistance

What is a Literature Review?

A literature review investigates and appraises existing knowledge, research, material and sources that have been published on a particular topic.  It can serve as a framework that informs the development and focus of an ensuing study, such as a thesis, article or research report. It can also be a stand-alone piece of research, such as an essay or conceptual article.

Literature reviews provide analyses that demonstrate a deep understanding of the existing literature, and commonly identify gaps and areas for future research to examine.  Importantly, literature reviews are diverse in their format and purpose:

• A literature review may be undertaken with a strong focus on critical evaluation, while others may adopt a more descriptive and exploratory approach.
• Some reviews concentrate on data, findings and methodologies, others examine ideas, themes, and theories.
• A review may aim to be summative in comprehensively synthesising all known literature on a topic. Other reviews may attempt to be more integrative in exploring related and interdisciplinary literatures.

This guide recognises the diversity of literature reviews. Rather than listing prescriptive advice, it aims to provide general guidance on the literature review process and share resources with you to help you get started.

Writing an Annotated Bibliography?

An annotated bibliography is a list of citations (articles, books, or other resources), each followed by a short descriptive paragraph that summarises the source's content and evaluates its relevance to the topic in question. For more information on how to write an annotated bibliography:

Visit the Academic Skills resource "Writing an annotated bibliography"

Writing a Systematic Review?

A systematic review appraises the literature in relation to a clearly-formulated question. It generally follows a strict protocol, with well-defined inclusion and exclusion criteria for the literature, data or studies assessed in the review, to ensure the transparency and reproducibility of the conclusions drawn by the review. To find out more about systematic reviews:

Visit the Systematic Reviews library guide

Strategies for an effective and comprehensive literature search

Maximise the quality, scope and appropriateness of the literature you review. When commencing a search:

• Determine key concepts and issues surrounding them
• Establish terminology so you can develop lists of key words and synonyms to use in your search
• Encyclopedias and key articles will often introduce topics and provide lists of key references

Reviewing a good range of the available literature on your topic is an important consideration. The tips below may be useful in helping you search for literature, and decide what literature to include in the scope of your review: 

• Consider the age of resources as appropriate for your review
• Use a variety of resources - books, journal articles, theses, conference papers and reports
• Search by keyword, subject, and also author
• Evaluate the information - is a journal refereed (peer-reviewed)? Is a source authoritative?
• Develop good referencing skills
• You can broaden your search by looking laterally for literature in related fields

Online guides that may help with your literature search

Research Essentials

Want to revisit the fundamentals of library research? The Research Essentials guide is a good starting point.

Finding Theses

Looking for examples of other theses to learn from and be inspired? The Finding Theses guide is highly recommended, especially for PhD students.

Staying Current

Want to keep up-to-date with the latest research? Visit the Staying Current guide for tips and tricks to setup alerts and manage information flows for you as a researcher.

Some things to consider before you start reading

• Keep your purpose in mind when you read
• Don't let the arguments in the text distract you
• Before beginning to read, take a few moments to think about what it is you are expecting from the article or chapter
• Skim-read the abstract, headings, conclusion, and the first sentence of each paragraph. Do you need to read everything with equal attention? Can you see where the arguments are headed?

Suggested critical questions to ask as you read

• What were the authors trying to discover?
• Why is this piece of research important?
• What was measured?
• What information do you have on the sample?
• How was the data collected?
• What were the results?
• What do the authors conclude and to what do they attribute their findings?
• Can you accept the findings as true?
• How can you apply these findings to your own work?

When results are conflicting, you might find it useful to ask the following questions:

• How similar were the programs used?
• Were different measurement instruments used?
• How were the programs evaluated?

Looking to improve your critical reading and notetaking skills?

Visit the Academic Skills "Reading and notetaking resources"

Structure of the review

The structure of your literature review will be based largely on your discipline and your topic. Your review is also influenced by how you decide to organise your argument(s):

• Chronological/historical
• Major authors/key studies
• Perspectives or positions taken on the topic under study
• Issues or debates (key issues/related issues)
• Methodological focus, etc.

Suggestions for structure

Organise your literature review according to an approach that best fits your topic. This means that you should not be too attached to an idea or template of how the literature review should ‘look’; instead, seek out effective models of literature reviews written in your discipline area. Broadly, the structure of a review may comprise the following elements:

• Provide an overview of the contents of the review. What is the significance and importance of the review?

Body (i.e. where you critically analyse the relevant literature)

• Synthesise the essence of literature that has dealt with your topic
• Consider any gaps or deficiencies, any inconsistencies or conflicting viewpoints and the broader implications of all this knowledge for your topic
• Draw together the important points and briefly explain how the information you have found addresses your original research question
• Indicate if more research is needed.

Important considerations

• Set parameters (e.g. inclusion and exclusion criteria for the literature referred to, date range)
• Make sure your literature review is a critical synthesis of the information you have discovered, and not just a summary
• Organise the material logically
• Make your purpose clear
• Emphasise recent/current research and developments
• Amount of detail around an issue is proportional to its importance
• Your own voice needs to be strong throughout the literature review - it needs to introduce and guide the reader through the research that is presented in the literature
• Provide commentary on design, methodology, conflicting arguments, and lack of conclusions
• Make sure citations and references are correct and accurate.

Any material you get from a source, even if you write it in your own words, needs to have a citation or footnote. Check the guidelines for your literature review, or speak to your supervisor, to determine which citation style you should be using.

Need help with your referencing? Click on the button below:

Visit the Re:Cite guide to referencing

Learn how reference management software can help you with referencing:

Visit the Options for Managing References guide

This section helps you find books and other resources which will help you write literature reviews.

Visit the Academic Skills "Reviewing the literature" page to find additional resources

Searching the resources

Use the following platforms to find resources on literature reviews:

Library Catalogue

Google Scholar

SAGE Knowledge

SAGE Research Methods Core

Search with keyword combinations such as:

"literature review*"

Create more searches by combining these keywords with the name of your discipline or subject area. For example:

(business OR economics)

writ* AND "literature review*"

architecture

writing  AND  "literature review*"

Also click on the following subject heading searches in the library catalogue:

Research - Methodology - Handbooks, Manuals, etc

Research - Evaluation

Suggested texts on academic writing

Other web-based resources

Academic skills  .

Contact Academic Skills for help with academic writing, critical reading and assessment planning.

The Library 

Contact the Library for help with finding research resources.

• Last Updated: Apr 8, 2024 4:21 PM
• URL: https://unimelb.libguides.com/lit_reviews

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• v.9(7); 2013 Jul

Ten Simple Rules for Writing a Literature Review

Marco pautasso.

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

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

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

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

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

Rule 1: Define a Topic and Audience

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

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

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

Rule 2: Search and Re-search the Literature

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

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

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

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

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

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

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

Rule 3: Take Notes While Reading

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

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

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

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

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

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

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

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

Rule 6: Be Critical and Consistent

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

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

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

Rule 7: Find a Logical Structure

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

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

Rule 8: Make Use of Feedback

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

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

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

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

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

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

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

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

Acknowledgments

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

Funding Statement

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

The Literature Review: 1. Introduction

• 1. Introduction
• 2. Why Do a Literature Review?
• 3. Methods for Searching the Literature
• 4. Analysing the Literature
• 5. Organizing the Literature Review

6. Writing the Review

1. About This Guide

This guide provides an introduction to the literature review process:

1. Introduction 1. About This Guide | 2. What is the Literature? | 3. What is a Literature Review? | 4. What a Literature Review is Not! | 5. Literature Reviews: An Overview for Graduate Students

2. Why Do a Literature Review? 1. Reasons for Doing a Literature Review | 2. Purposes of a Literature Review | 3. Components of a Literature Review

3. Methods for Searching the Literature 1. Tasks Involved in a Literature Review | 2. Skills Required for Conducting a Literature Search | 3. Searching Techniques | 4. Sorting the Literature | 5. Notetaking | 6. Questions to Keep in Mind

4. Analysing the Literature 1. Recording the Literature | 2. The Evolving Literature Review | 3. Questions to Ask

5. Organizing the Review 1. Organizing Principles | 2. Structure of the Literature Review | 3. Tips on Structure | 4. Selected Online Resources | 5. A Final Checklist

1. Writing the Literature Review Part 1: Step-by-Step Tutorial for Graduate Students | 2. Writing the Literature Review Part 2: Step-by-Step Tutorial for Graduate Students | 3. Tips for Effective Literature Reviews | 4. Literature Review Samples | 5. Resources @ UWISA Libraries

2. What is the "Literature"?

The works you consult in order to identify the ideas and knowledge that have been established on your topic:

Journal articles are the most common sources of materials for literature reviews. They provide:

• concise and up-to-date information
• some guarantee of the quality of the work they publish

Books are usually less up-to-date than journal articles. They are:

• useful for providing overall summaries of the state of knowledge in an area
• a starting point for finding more detailed information sources

Conference proceedings may contain research not yet published in journals.

Reports of government and international agencies

Theses and dissertations can be valuable sources of original research

Newspapers and magazines may inlcude news stories on research that you can follow up to find more detail

Web pages/documents on the Internet

3. What is a Literature Review?

Definitions

" The analysis, critical evaluation and synthesis of existing knowledge relevant to your research problem, thesis or the issue you are aiming to say something about " (Hart, 2018, p. 3 & 4)

"A literature review uses as its database reports of primary or original scholarlship and does not report new primary scholarship itself.... Second, a literature review seeks to describe, summarize, evaluate, clarify and/or interrogate the content of primary reports." (Cooper, 1998, p. 7)

"A literature review is a written document that presents a logically argued case founded on a comprehensive understanding of the current state of knowledge about a topic of study. This case establishes a convincing thesis to answer a study's question." (Machi & McEvoy, 2016, p. 5)

• Writing a Literature Review A useful guide with respect to the where, when, why, what and how of the literature review.

4. What a Literature Review is Not!

It is not an annotated bibliography!

An annotated bibliography "is a list of citations to books, articles, and documents. Each citation is followed by a brief (usually about 150 words) descriptive and evaluative paragraph, the annotation. The purpose of the annotation is to inform the reader of the relevance, accuracy, and quality of the sources cited." Definition from Cornell University Library, available at http://guides.library.cornell.edu/annotatedbibliography

Major Differences

Literature Review

• Written in essay style and organized around a central idea or thesis
• A single source may be referred to numerous times depending on its importance in the field or its relationship to other sources

Annotated Bibliography

• An alphabetical list of sources accompanied by summaries
• A single source appears just once

5. Literature Reviews: An Overview for Graduate Students - NCSU Video

Acknowledgement

Research guide updated and maintained by petronetta pierre - robertson indexer/documentalist.

Sincere thanks to Jennifer Warburton of the University of Melbourne for permission to draw on some of the content of her Guide .  

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Open Access

Peer-reviewed

Research Article

Identifying factors that influence electric vehicle charging station performance in expanding networks

Roles Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Validation, Visualization, Writing – original draft, Writing – review & editing

* E-mail: [email protected]

Affiliation Department of Urban Technology, Faculty of Technology, Amsterdam University of Applied Sciences, Amsterdam, The Netherlands

• Rick Wolbertus

• Published: April 26, 2024
• https://doi.org/10.1371/journal.pone.0302132
• Reader Comments

Charging infrastructure deployment has taken off in many cities with the rise of the number of electric vehicles on the road. Expansion of infrastructure is a matter of prioritisation of resources to optimise the infrastructure. This paper explores how to measure charging station performance, to address the challenges that policy makers face. These performance indicators are used in a regression model, based upon current utilisation of the network, to predict which charging stations perform best. The results show that a model based on available geographical data and performance metrics of the current network are best combined to predict infrastructure performance. The variability between public charging stations is however big, as frequent user characteristics do determine the performance to a large extent.

Citation: Wolbertus R (2024) Identifying factors that influence electric vehicle charging station performance in expanding networks. PLoS ONE 19(4): e0302132. https://doi.org/10.1371/journal.pone.0302132

Editor: Maurizio Fiaschetti, UCL: University College London, UNITED KINGDOM

Received: July 31, 2023; Accepted: March 28, 2024; Published: April 26, 2024

Copyright: © 2024 Rick Wolbertus. This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: All relevant data are within the manuscript and its Supporting Information files.

Funding: This research is a part of the Future Charging project funded by SIA RAAK (NWO). Project number: RAAK.PRO03.128. https://regieorgaan-sia.nl/v I am grateful for the collaboration and data provision from all partners involved. Partner cities Amsterdam, Utrecht, The Hague and Rotterdam have provided the relevant data and have thought along with relevant predictor variables and provided feedback on early results. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.

1. Introduction

Electric vehicles (EVs) have reached significant market shares in a multitude of countries in recent years. The market develops from early adopters to mainstream consumers as the range of vehicles increases and prices decrease [ 1 ]. Increasingly stringent regulations in markets such as the European Union push most Original Equipment Manufacturers (OEMs) to announce more electric models to be launched in the near future [ 2 ]. OEMs make plans to completely phase out their gasoline portfolio within a decade [ 3 ]. Alongside the rise of electric vehicles, charging infrastructure has been developed in many countries to accommodate for the growth in the number of vehicles. Despite initial infrastructure development, there are still significant worries if the roll out can keep up pace with the adoption pace of vehicles.

Sufficient charging infrastructure is considered the major bottleneck for a swift transition to electric mobility [ 4 , 5 ]. EV charging is known to mostly take place at home, workplace and public locations [ 6 , 7 ]. For those without a private charging opportunity, public on-street charging is a substitute for home and workplace charging. Especially dense urban areas need sufficient public charging infrastructure as the majority of parking is done on-street [ 8 ]. Realisation of charging infrastructure in cities requires to balance different aspects such as public space, parking, business cases and electricity grid integration [ 9 , 10 ]. Policy makers face the problem that the definition of charging infrastructure success is not one-dimensional, which in turn makes it difficult to capture and assess its performance.

Research on the topic of charging infrastructure networks has mainly focussed on optimisation [ 11 , 12 ], which assume the city as a blank page in which the infrastructure must be realised. These studies often rely on driving patterns from gasoline driven cars or geographical information such as income, urban density etc. in combination with assumptions about charging strategies and EV adoption [ 13 , 14 ]. In reality, the realisation and expansion of infrastructure is much more complex, continuous operation in which local circumstances play a major role. Government incentives vary, which creates temporal dynamics in the EV adoption rate. Technological developments lead to new patterns in charging behaviour, which have been difficult to predict [ 15 ]. Charging point operators (CPOs) do not operate in a blank page, but continuously expand the current infrastructure in which they decide where and when to install the next station, instead of installing a multitude of chargers at once. From a CPO and policy maker perspective, a prioritisation is required, as funding and capacity of sufficiently qualified personnel are limiting factors. Strategies for expanding charging infrastructure in already existing networks have been missing so far.

This paper aims to fill this gap in two steps. First, the paper aims to define a measure of charging infrastructure success that copes with the multidimensionality of the problem at hand. To this end, the literature on charging infrastructure planning is reviewed with respect to performance indicators. Following this analysis, a new multi-dimensional standard for charging infrastructure success is proposed. Secondly, the paper develops a model to identify the variables that influence the success of charging infrastructure in existing networks with the use of data from the use of charging stations. This is done by using a large database with 1708 charging stations and 8.5 million charging sessions recorded from 2016 to 2020 in the Netherlands.

2. Literature review on electric vehicle charging station performance

A large part of the literature on electric vehicle charging infrastructure focuses on charging infrastructure planning. Reviews on the literature on this topic [ 16 – 18 ] show that the planning studies can be divided into node [ 19 ], tour [ 20 ] and path-based studies. Most studies, although not all, assume the city (or country) as a blank page in which charging infrastructure should be realised. Charging infrastructure is optimised according to a different set of parameters or optimisation.

The work from Motoaki shows that such planning studies however often do not resemble practice as local circumstances and policies play a major role in investment decisions as well as the historic development of charging infrastructure roll-out. Other studies take a broader look by not simply looking at actual locations but include business decisions [ 21 – 23 ] or look at stakeholder interests in general [ 24 ]. More recent work uses initial roll-out of charging infrastructure in frontrunner cities as a proxy to estimate infrastructure demand [ 20 ]. These studies show that geographic information systems (GIS) can be used for planning by using factors such as the built environment and income at the neighbourhood level [ 12 , 25 ]. Adenaw & Lienkamp [ 26 ] use these GIS models, which are now widely used in practice, as an input into a 4-step process which agent-based modelling and a heuristic-based approach for location decisions to match more commonly used practices.

Charging station performance is used as a condition in charging station planning studies [ 14 , 27 ]. Performance at the charging station level is measured as energy transferred to match requirements of a positive business case for the charging station owner [ 22 , 28 , 29 ]. Charging stations success is however secondary to the broader goal of meeting transportation needs from EV drivers in most of these studies. Gnann, Plötz, et al., for example try to minimize the number of charging stations to facilitate all charging sessions but include in their model that charging stations must be profitable for them to be actively operated. Islam et al. [ 30 ] try to minimize detour times for drivers using public data from travel times from Google maps. Other studies that focus on the charging point operator side also focus on the business case of charging points, trying to calculate the turnover needed in different scenarios or tariff settings [ 31 – 33 ]. These latter studies have a purely economic approach to the matter, while measuring performance could benefit from a broader perspective.

A similar trend is seen in descriptive studies on charging infrastructure use or charging behaviour. The focus is on the electric driver, partly because the data collected is from a drivers’ perspective [ 34 – 36 ] but also studies that collect data at the charging point translate this into the user behaviour [ 37 – 39 ] Other studies do focus on the charging point perspective such as Morissey, Weldon & Mahony [ 40 ] the heterogeneity in charging needs across different types of infrastructure. Gnann et al. [ 41 ] combine data from fast charging stations with travel data to develop a queuing model. They include the user perspective by examining the average queuing time but also include charging station metrics such as occupancy and profitability of the charging station. The vantage point for charging station success varies between EV drivers and the CPO across the different studies.

Charging station success is discussed in most studies regarding charging infrastructure but has so far been the focus point in only a limited number. Work by Helmus et al. [ 42 ] focusses on comparing success for different roll-out strategies among multiple performance indicators such as occupation, unique users and charging time. Helmus & van den Hoed [ 43 ] looked at a wide array of performance indicator and discussed their implications for policy makers. Straka et al. [ 44 ] tried to predict charging station success based on contextual factors. Success was defined with seven different indicators such energy consumed and the number of different cars charging at a charging station. Similar work was done by Almaghrebi et al. [ 45 ] which compared different machine learning techniques to predict success. Success was defined one-dimensional in terms of energy drawn from the charging station. A general definition of success has been missing so far in literature and has not been a specific focus point of research.

2.1 Contributions

The review on charging infrastructure performance has shown that current research on charging station performance has been limited and that an analysis of how current charging station performance influences future performance is missing. As well the review has shown that roll-out simulation studies that include charging station performance as a metric, mainly focus on the business case of the charging station and therefore the energy drawn from the station. The multidimensionality of the problem which many policy makers and charging point operators face has not been translated in the relevant Key Performance Indicators (KPIs) in literature.

This paper aims to fill the research gaps as identified as above. A systematic analysis of charging station performance indicators is proposed based upon a literature review and a reflection on the pros and cons of these indicators is given in the section Key performance indicators for charging stations (Section 2) . This results in a proposal on how to systematically evaluate charging station performance. In the section Predicting charging station success (Section 3) , this paper aims to provide insight into the relationship between current charging station network performance and the performance of newly installed stations. This contributes to the body of knowledge on how to expand charging station networks while many studies have focused on building a network from scratch.

3. Key performance indicators for charging stations

3.1 methodology to determine kpis.

Literature on charging station deployment and performance is used to derive the most used KPIs. Literature was found using Web of Science with the key words Electric vehicle charging infrastructure in the title of the paper. The search focussed on papers from 2016 to 2020 to only include more recent papers. This choice was made as a rapid development in electric vehicle adoption and strategies for charging station placement has taken place during this time. This resulted in 108 papers. An overview of the number of papers in the database over time is given in Fig 1 , which shows a clear increase in the number of papers published over the years.

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https://doi.org/10.1371/journal.pone.0302132.g001

To be able to make a sound review of the KPIs used in this paper only the top 25 cited papers were used for this analysis. Citations were reviewed as average citations per year to prevent a bias towards older papers. Abstracts were reviewed to see if these papers were about charging infrastructure planning or performance. This review resulted in omitting papers which sole focus was on shared or autonomous vehicles or purely focussed on electricity grid integration. The 25 papers that were reviewed can be found in Appendix A in S1 Appendix . Several papers also included KPIs that focussed on different actors such as the EV driver or the grid operator. We have excluded these KPIs from this analysis to only focus on KPIs that are related to charging infrastructure performance. The number of papers was limited to 25, to make a thorough review of these papers. Also, it was noted during the evaluation that after the initial top 15 papers, no new KPIs were found.

3.2 Results

The results of the analysis ( Table 1 ) shows that ‘Energy (kWh)’ is seen as the most used performance indicator for charging infrastructure, highly related with the turnover at these charging stations. Turnover is however sometimes explicitly mentioned as a different indicator as this could depend on the tariff system used at these stations or from different sources such as advertisement. The energy drawn is closely related to the power of the charging stations at a specific time. Although papers exclusively aimed at grid integration were excluded from the analysis, this topic has a high priority among researchers in this field. Peak power, or ways to reduce this, are a prominent indicator for charging station performance.

https://doi.org/10.1371/journal.pone.0302132.t001

The second most mentioned performance indicator is the time connected or charging at a station. These sometimes overlap, especially in case of DC fast charging stations, but are also sometimes explicitly different in case of slower charging at AC charging stations. EV drivers park at these charging stations and time connected leads to unutilised connection time. A different measure related to connection time often mentioned is the occupancy rate displayed as % of the time connected. The studies relate this occupancy rate to parking issues as fears over underutilisation compared to regular parking spots is an issue for policy makers.

Broader indicators for charging station success include the number of charging sessions and unique users at these stations. The number of charging sessions and unique users are different KPIs for serving the demand from EV drivers. In different areas these can have different implications. A high number of different users might indicate an area with a lot of visitors, which could in turn lead to a lot of charging sessions. Locations outside these areas might have a few frequent users but still have a similar or even higher number of charging sessions. Social costs parameter studies try to include aspects such as impact on the local environment and equality issues, but its application varies across the papers.

Based on this analysis, this paper focuses on four KPIs of EV charging which cover the broad aspects of EV charging. These are: Energy (kWh), time connected to the charging station, number of charging sessions and number of unique users. The factor of turnover is left out as this highly correlates with energy drawn, assuming a per kWh/charge or a time connected charge. Analysing this separately would not yield new results. Similarly, occupancy rate is not included as it is a different way of measuring time connected to a charging station. The KPI of power is limited due to the nature of the charging stations analysed in this aspect, maximum 11kW. Social costs were found to be varying in definition across the papers and therefore not suitable in this analysis. Turnover from advertisement is not related to roll-out strategy and given the diverse nature of this income any analysis would not lead to generalisable conclusions. This leaves four relevant KPI’s to be included in this research.

4. Predicting charging station success

4.1 approach.

The approach proposed in this paper builds upon the idea that the success of newly placed charging stations depends on the performance of charging stations in the surroundings in the time leading up to the placement of this newly placed station. This would allow CPOs to assess the placement of new charging stations not only based upon parameters of the built and social environment, on which most models rely, but also incorporate actual charging network performance in their decision-making process. This concept would better fit with the daily operation and prioritisation within the decision-making process of charging stations. This idea and timeline of measurement has been visualised in Fig 2 .

https://doi.org/10.1371/journal.pone.0302132.g002

To assess which charging stations perform well, the four Key performance indicators for charging stations are used and an additional performance indicator for general success. This overall performance indicator encompasses the four performance indicators as one (see section 4.2 on the calculation).

To predict which charging stations are a success the same four KPIs of the surrounding charging stations are used with an addition of a social network performance indicator, which allows to not only view the performance of individual charging stations in the surrounding of the newly placed charging station, but also the social network effects between them. This is measured by the number of users that must deviate from their favourite charging station (close to home or workplace) to one in the surrounding. This behaviour indicates that charging station have more demand than station can handle and therefore users must search for other available stations. This cannot be directly measured by the four proposed KPIs and therefore this new parameter is created.

4.2 Methodology predicting success

To predict charging station success data from public charging stations from four Dutch cities are used (Amsterdam, Rotterdam, Utrecht, The Hague). Data from level 2 charging stations (2 sockets each up to 11kW) were collected from 2014 up to and including February 2020. Collection of the data was done through a collaboration with CPOs that operate in these cities within the Future Charging research program. Data collection methods have varied throughout the years and depending on the CPO. Most recently, data is being collected through a direct connection with OCPI protocol. Data is stored in a MS SQL database. Data beyond February 2020 was also collected but not considered due to the impact of the Covid-19 lockdown. Data from 1708 charging stations and 8.5 million charging sessions were collected. Data as in Table 2 were collected for each charging session. More on the data collection, processing and storage etc. can be found in Wolbertus et al. [ 46 ].

https://doi.org/10.1371/journal.pone.0302132.t002

To measure charging station success data was transformed to create a single datapoint per KPI per charging station each week of which in the average was taken to create a single datapoint per charging station (1708 in total). The timeframe of a week is used as it is consistent in length (compared to months) and has a regular pattern in terms of work and weekend days. KPIs are a sum of the number of kWh charged, unique users, time connected and number of charging sessions (see section 3.2 for the selection of these KPIs). To compare success, the KPIs are normalised in comparison to charging stations within the same city in the same week. Data is normalised by dividing the KPI by the average of all charging stations in the same city in that respective week. Hence, the score will be 1 if the charging station performs exactly the average. As an example, if at the charging station 100 kWh is charged in week 1 and the average across all charging station in week 1 is 200 kWh, the score is 0.5 (for easier interpretation this is later multiplied with 100). The average of this score across 2 years (12–36 months after installation) is used in the model, this results in a single data point per station. This comparison overcomes differences in adoption levels over time. Data normalisation allows to combine the four KPIs into a single parameter for charging station success. A fifth KPI is therefore calculated that is again normalised after normalised scores from each KPI are averaged. This fifth parameter (average score) is the general performance of charging station. Data is also reviewed considering the age of the charging station. The placement date is considered the first time a charging station is used, as charging stations are tested on site after installation. A single data point, the average performance per week for each charging station is entered into the model. This is the average of the weeks in year 2 and 3 after the installation (see section 4.3 on why only these weeks are considered in the model). In total 1708 charging stations were included in the analysis. Table 3 provides and overview of the dependent variables.

https://doi.org/10.1371/journal.pone.0302132.t003

Charging station success is modelled using a linear regression model on each of the KPIs (Model specification is given in Appendix D in S1 Appendix ). Predictor variables include a summary of several statistics from surrounding charging stations that were there prior to the installation of the new charging station. Charging stations within 500 meters (as-the-crow-flies distance) were selected. Different radiuses were tried, but either resulted in a lack of data or no significant differences between the models could be found. Data was collected from six to up to three months prior to the installation of the charging station. This period was selected in consultation with policy makers and charging station operators. The period resembles the real-world decision period for expansion of charging networks. Three months are needed on average to arrange permits, grid connection and placement of the charging station. A three-month observation period was chosen to prevent incidental outliers in the data to inform decisions.

Predictor variables include number of sessions, energy charged (kWh), unique users, time connected (hours) and the number of charging stations in the given radius. Additionally, a variable is added to express the convenience in finding a charging station (see section 4.1 for an elaborate explanation). This is expressed as the share of charging sessions that do not take place at favourite charging station of the EV driver. The favourite charging station is determined by selecting the most used charging station of the EV driver which is identified by its RFID ID. Only EV drivers that charge at least 5 times in the same area are taken into consideration, as the favourite charging station cannot be determined for visitors.

To control for effects of the area in which the charging station is placed, geographical information on the sub-district level on income, type of built environment and paid parking is added [ 47 ]. Information about the facilities in the surrounding are retrieved from the OSRM database using the nominatim package in R. Given that charging stations provide a maximum of 11kW these stations are mostly used for charging while being parked for a longer time. The research focusses on facilities that would allow for longer parking times and not necessarily attract traffic for stop & go charging (e.g. fast charging > 50kW). The number of facilities is counted within a 500-meter range (as-the-crow-flies distance) of each charging station. Other distances (see Appendix B in S1 Appendix ) were tried as well, but 500 meters provided the best fit. Data was retrieved only once (2020) and has been kept constant for the charging stations across time. A dummy variable is added to indicate the year in which the charging station was first used, 2014 is the reference level. Controlling for these factors also gives the opportunity to compare the model based on charging data to those models that solely rely on geographical information. The added value of including current charging stations performance can be estimated. Table 4 provides an overview of all independent variables used.

https://doi.org/10.1371/journal.pone.0302132.t004

The model was tested for multicollinearity using VIF scores. There was a significant correlation between number of sessions and other charging station related predictor variables (ranges between 0.7–0.8, see Fig 3 , Appendix C in S1 Appendix ). Yet, as these variables are central to the research question at hand these were not discarded. To test the impact on the results, the same model was tested with a stepwise regression. The stepwise regression results kept including all the different charging station variables across all models and therefore it was decided to include in the final model. To test for heteroskedasticities the Breugsch-Pagan test was used. Results were insignificant with exception for the model of connection time. A model on the log results of connection time were tested but this did not solve the heteroscedasticity. Given the similar results across all models, results are still considered useful. Results for multicollinearity and heteroskedasticities for each model can be found in Appendix C in S1 Appendix . Although no correlation of the error-terms was expected a Durbin-Watson test was performed for each model. Results (p = 0.4791) showed no correlation.

https://doi.org/10.1371/journal.pone.0302132.g003

4.3 Descriptive results

Table 5 has descriptive statistics for the charging data used in this research across all years. It shows that on average nearly 10 kWh is charged per session, amounting to 117 kWh per charging station (2 points) in 12 charging sessions per week. These charging sessions are done by more than 6 different users per station each week, although there is a large variability in this number. Average power is below 1kW far below the rated power (3.7-11kW) of the stations indicating sufficient idle time during the charging sessions.

https://doi.org/10.1371/journal.pone.0302132.t005

Fig 4 shows the development of the KPIs over time given per week. This shows a strong growth for most KPIs. This corresponds both the increased adoption of EVs in the Netherlands as well the shift from plug-in hybrid vehicles to full electric, due to a change in government incentives [ 48 ]. This increased the average energy per charging session dramatically, from 8.4 kWh in 2014 to 15.8 kWh in early 2020. All other factors show a smaller increase, indicating increased utilisation of the charging stations as a result of a larger number of EVs on the road. These are however limited in their increase due to the rival nature of charging stations; once occupied they cannot be used by others.

Black line shows actual measurement, blue line shows rolling average. The analysis therefore focuses on the performance of charging stations relative to each other in the same week of time, but also takes into account the age of the charging station. The performance relative to the age (compared to charging stations in the same week) is shown in Fig 5 . This figure shows that for all four considered KPIs that newly placed charging stations take up to a year to perform at the same level as other charging stations within the same city. Normalisation compared to the age of the station shows that the KPIs all follow a similar pattern which allows them to be included in a general overall indicator. In the regression model only performance in year two and three after placement of the charging station is therefore considered. Beyond this the number of charging stations drops significantly as most stations were placed in the period 2017–2018. Analysis of such figures is therefore no longer considered reliable.

https://doi.org/10.1371/journal.pone.0302132.g004

Black line shows actual measurement, blue line shows rolling average.

https://doi.org/10.1371/journal.pone.0302132.g005

Regression models are estimated for all different KPIs and results for all shown in Table 6 . R 2 is displayed for each model, and p-values for each variable. Bold font indicates significance at 0.05 level for each of the variables. The predictor variables are split into three categories, intercept and dummy variables for year of charging station placement, variables related to the surrounding charging stations and geographical factors.

https://doi.org/10.1371/journal.pone.0302132.t006

In general, the predictive value of the models is relatively low, varying from a R 2 -value of as low as 0.096 for the energy model to as high as 0.303 for the unique user model. Dummy variables for the year of installation are significant in all models, but the relative importance of these dummies is rather low (~5% of the explained variance). The dummy variables for year installed follow the trend as shown in Fig 4 that older charging stations perform better on all variables, hence all year-dummies are negative as they compare to the oldest stations installed in 2014. In general, it is found that variables related to the charging stations have the highest relative importance (45–55% of explained variance) followed by geographical factors (35–45% of explained variance).

4.5 Variables related to charging stations in the surrounding

As it comes to predictors of the measured performance of neighbouring charging stations it can be found that the number of charging sessions is significant parameter in all of the models. The number of sessions is also the parameter with the highest relative importance among the factors related to surrounding charging stations (13.3% of explained variance in the average score model and 19.4% in the model for sessions). The number of sessions is best predictor for charging station success for all relevant KPIs, implying that simply counting sessions is a good indicator for charging demand.

Current occupation of charging stations, measured in the connection time is a significant parameter in all models. The predictive value, is much less than parameter that represents the number of charging sessions. This is because in some parts of the cities charging stations are mainly used for overnight charging. This leads to high occupation but a lower score on other factors such as energy, number of sessions and unique users. Some of these charging stations are only used by a few frequent users which use the charging station as substitute for home or office charging which results in high occupation but lower scores for other KPIs. A similar trend is seen for the energy parameter, results are significant, but the relative importance is very low. This can be explained by the fact that the energy parameter input is also highly dependent on the battery size of frequent users of the charging stations. Frequent plug-in hybrid users could lead to a high number of sessions and high occupation but low energy, compared to a full electric vehicle with a large battery. A newly installed charging station is not likely to attract the frequent users of already existing stations, and the battery size of new users is hard to predict. This is more likely dependent on government incentives for type of vehicles (e.g., PHEV vs FEV subsidies).

Remarkable is the finding that a high number of unique users leads to lower performance across all parameters (except the number of users). The interpretation is that a high number of unique users indicates a place suitable for a lot of infrequent visitors to city (e.g., for shopping, commercial visits, tourists). A similar trend is observed in the No. of businesses parameter. These stations do not have frequent users which perform better on the other KPIs as they often make daily use of the charging stations. Infrequent users are also likely to only stay for a shorter time (impact on connection time and energy).

The share of charging sessions not at the favourite charging station is a significant factor in 2 out of 5 models. Current users cruising to find an available charging station are a relevant predictor for charging station success in the future. Remarkable is that the current performance in terms of energy, and thus business case, is only significant in the energy model itself and has a high relative importance in this model as well (18.4% of variance explained). This also indicates that users from the same neighbourhood will make use of new charging stations in the surroundings, leading to a higher turnover. The actual number of stations within the 500-meter radius is a significant parameter in most models, but its relative importance is low, explaining only a few percent of the variance in each of the models.

4.6 Geographical factors

The geographical variables have a significant contribution to the model’s performance showing that a combination of current performance and geographical based factors can complement each other in predictions of charging station success. This is relevant for all models with a relative importance varying between 27% (Number of sessions) and 43% (Unique users) across the different predicted KPIs.

The models show that paid parking and the income level in a neighbourhood are the best predictors for charging station success. Especially paid parking is a good predictor for the number of different unique users, in line with expectations. Paid parking areas are mostly close to the city centre and therefore will attract different EV drivers that do not charge their EV regularly in the area. In the model used to predict the number of unique users, this is parameter accounts for 27.4% of the explained variance. However, it is not only a good predictor for the number of unique users, but also for other factors such as energy which was less in line with expectations. This could be explained by the fact that these users have relative short charging sessions in which most of the time is used for actual charging instead of idle connection time.

The income level is also a highly significant parameter in most models. Income levels are known to be a good predictor for EV adoption as purchase prices of these models are higher than gasoline equivalents. As well, higher income levels are more likely to purchase or lease new cars than relative lower income levels. Yet, it is striking that this also results in a better charging station performance, as the number of charging stations should grow alongside the number of EVs. Possible explanation is that in neighbourhoods with higher income levels a larger network of charging stations is present. This leads to network effects in which charging stations are better used as a whole, while the EV driver does not experience a reduced availability.

Housing and business density have little predictive value for charging station success. In general, the parameters could indicate general charging demand, but this does not influence charging station performance, or this is captured by the income variables. Only the number of businesses is a significant parameter for the number of unique users as it indicates, just as paid parking, city centres with a lot of visitors.

More specific parameters on the neighbourhood facilities such as the number of shops, restaurants show that these can be of some influence but are often insignificant. Only the number of restaurants and number of public transport stops seems to have a small positive significant impact. The number of public transports stops has the highest impact of the number of unique users which has a relation with shared free floating electric cars which are seen as an extension of public transport. Shared electric cars are more likely to be charged near public transport stops. Given that free floating shared vehicle operators have a large fleet, of which the users can drive and park the car anywhere in the city, this could generate a lot of different users (as measured by looking at the ID of the car) at a charging station. The general lack of significance of these parameters could be explained by the idea that most public charging stations have mostly been placed to accommodate the inhabitants or visiting workers in mind. This than also presents most charging at these stations. The facilities included in this model would mainly be related to visitors in the city, which represent a fraction of the charging sessions and thus does not influence the performance of these stations.

5. Conclusions

Charging station performance is a multi-dimensional problem from a policy maker perspective. And should therefore be defined as such. This research proposes to analyse and predict success alongside four factors: energy, charging sessions, occupation and unique users. These factors should be compared to the performance of stations which operate in the same time span as the temporal aspects, due for example shifting incentives and battery developments at OEMs, are key factors that determine this performance. The proposed factors are also currently used in different ways to assess charging station performance in literature, although a structured approach to measuring success was missing.

With the use of the relevant KPIs this paper has assessed which factors could help predict charging station performance of new charging stations in current networks. Such a methodology is an addition to current models that predict EV uptake based on geographical based models and would allow CPOs and policy makers to prioritise resources on a relative short term. Results show that indicators of current charging station performance add to the prediction power of geographical-based models, although general predictability of charging station performance is relatively low (maximum R 2 of 0.259).

The number of charging sessions, occupation and share of charging sessions at non-favourite locations were found to the best predictors of charging stations success in a broad sense. In terms of business case, related to energy sold, the models showed poor predictability. Analysis of the same data as used in this paper showed that most charging stations are used by a limited number of frequent users [ 49 ]. The charging behaviour and battery capacity of those EV drivers have been found to highly correlate with performance in terms of energy charged. A charging station mostly used by two plug-in hybrid vehicles compared to two full electric vehicles will perform less in that respect but will show good performance in terms of occupation and charging sessions. This type of model is however not able to predict what type of vehicle new EV drivers purchase. This is however a dominant factor, especially in this case as the Netherlands switched incentives for PHEVs and BEVs radically over time. The model should therefore be expanded with a parameter that includes market segmentation.

5.1 Limitations

This paper is used data from charging stations in the Netherlands to calculate the impact of past charging station performance on future performance. The data that is used comes from dense urban areas in which many users rely on on-street parking facilities. As such, this research should also be interpreted on a case study for similar urban areas in which cities are asked to (co-)develop public infrastructure which elsewhere would be resolved by private and workplace charging.

The performance of charging stations, as shown by the results, is also very time dependent. Outside factors such incentives for placement and purchase subsidies can play a significant role. This research has included factors to account for such factors but not all variance is likely to be captured. Any application of these results should always be interpreted in the context of local circumstances. This research should be used to give indication on which factors, in which direction and the approximate size of the effect of these factors.

5.2 Policy and practical implications

Results show that a combination of geographical and current network performance complement each other in terms of forecasting charging station performance. As a result, policy makers and charge point operators would have to look for best practices to combine these. A recommendation would be to use geographical parameters in long term planning as these are best be suited to predict EV adoption and therefore infrastructure need on a larger scale. Based on this initial planning, prioritisation of resources is best done with use of the current network performance added with information on sales of electric vehicles in the neighbourhood. Frequent users still largely determine the performance of charging stations. However, if charge point operators look at performance on a more network level, information on network performance is highly relevant and placement strategies should also include network effects and not solely look at single point performance.

In general, this research shows that due to the high variability among the use of charging stations, the dominance of the type of user on level 2 charging infrastructure performance (due to the rival nature of a charging station) and variations in purchase policies overtime, charging station performance is difficult to model with a high certainty at the level of a single charging station. Future work could have a closer look at the influence of network size on the relevance of each indicator although interactions between these variables did not lead to increased performance of the models at hand. As well, due to low predictability at a single station level, further work could be done on the performance of the network as a whole or in certain neighbourhoods. This would moderate some of the effects found at the single station level.

Supporting information

S1 data. the data file contains information about each charging location used to build the models..

It contains information about the charging station performance and the explanatory variables that are used. Data can be used to recreate the model.

https://doi.org/10.1371/journal.pone.0302132.s001

S1 Appendix.

https://doi.org/10.1371/journal.pone.0302132.s002

Acknowledgments

I am grateful for the collaboration and data provision from all partners involved.

Partner cities Amsterdam, Utrecht, The Hague and Rotterdam have provided the relevant data and have thought along with relevant predictor variables and provided feedback on early results.

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