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Literature Review: A Definition

What is a literature review, then.

A literature review discusses and analyses published information in a particular subject area. Sometimes the information covers a certain time period.

A literature review is more than a summary of the sources, it has an organizational pattern that combines both summary and synthesis. A summary is a recap of the important information of the source, but a synthesis is a re-organization, or a reshuffling, of that information. It might give a new interpretation of old material or combine new with old interpretations. Or it might trace the intellectual progression of the field, including major debates. And depending on the situation, the literature review may evaluate the sources and advise the reader on the most pertinent or relevant.

But how is a literature review different from an academic research paper?

While the main focus of an academic research paper is to support your own argument, the focus of a literature review is to summarize and synthesize the arguments and ideas of others. The academic research paper also covers a range of sources, but it is usually a select number of sources, because the emphasis is on the argument. Likewise, a literature review can also have an "argument," but it is not as important as covering a number of sources. In short, an academic research paper and a literature review contain some of the same elements. In fact, many academic research papers will contain a literature review section. What aspect of the study (either the argument or the sources) that is emphasized determines what type of document it is.

( "Literature Reviews" from The Writing Center, University of North Carolina at Chapel Hill )

Why do we write literature reviews?

Literature reviews provide you with a handy guide to a particular topic. If you have limited time to conduct research, literature reviews can give you an overview or act as a stepping stone.

For professionals, they are useful reports that keep them up to date with what is current in the field.

For scholars, the depth and breadth of the literature review emphasizes the credibility of the writer in his or her field. Literature reviews also provide a solid background for a research paper's investigation.

Comprehensive knowledge of the literature of the field is essential to most research papers.

Journal Articles on Writing Literature Reviews

Some Books from the WU Catalog

The SAGE handbook of visual research methods [electronic resource] by Edited by Luc Pauwels and Dawn Mannay. ISBN: 9781526417015 Publication Date: SAGE Publications, Inc., 2020.

Helpful Websites

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

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:

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?

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

Schools & departments

Literature review

A general guide on how to conduct and write a literature review.

Please check course or programme information and materials provided by teaching staff , including your project supervisor, for subject-specific guidance.

What is a literature review?

A literature review is a piece of academic writing demonstrating knowledge and understanding of the academic literature on a specific topic placed in context. A literature review also includes a critical evaluation of the material; this is why it is called a literature review rather than a literature report. It is a process of reviewing the literature, as well as a form of writing.

To illustrate the difference between reporting and reviewing, think about television or film review articles. These articles include content such as a brief synopsis or the key points of the film or programme plus the critic’s own evaluation. Similarly the two main objectives of a literature review are firstly the content covering existing research, theories and evidence, and secondly your own critical evaluation and discussion of this content.

Usually a literature review forms a section or part of a dissertation, research project or long essay. However, it can also be set and assessed as a standalone piece of work.

What is the purpose of a literature review?

…your task is to build an argument, not a library. Rudestam, K.E. and Newton, R.R. (1992) Surviving your dissertation: A comprehensive guide to content and process. California: Sage, p49.

In a larger piece of written work, such as a dissertation or project, a literature review is usually one of the first tasks carried out after deciding on a topic. Reading combined with critical analysis can help to refine a topic and frame research questions. Conducting a literature review establishes your familiarity with and understanding of current research in a particular field before carrying out a new investigation. After doing a literature review, you should know what research has already been done and be able to identify what is unknown within your topic.

When doing and writing a literature review, it is good practice to:

Conducting a literature review

Focusing on different aspects of your literature review can be useful to help plan, develop, refine and write it. You can use and adapt the prompt questions in our worksheet below at different points in the process of researching and writing your review. These are suggestions to get you thinking and writing.

Developing and refining your literature review (pdf)

Developing and refining your literature review (Word)

Developing and refining your literature review (Word rtf)

Writing a literature review has a lot in common with other assignment tasks. There is advice on our other pages about thinking critically, reading strategies and academic writing. Our literature review top tips suggest some specific things you can do to help you submit a successful review.

Literature review top tips (pdf)

Literature review top tips (Word rtf)

Our reading page includes strategies and advice on using books and articles and a notes record sheet grid you can use.

Reading at university

The Academic writing page suggests ways to organise and structure information from a range of sources and how you can develop your argument as you read and write.

Academic writing

The Critical thinking page has advice on how to be a more critical researcher and a form you can use to help you think and break down the stages of developing your argument.

Critical thinking

As with other forms of academic writing, your literature review needs to demonstrate good academic practice by following the Code of Student Conduct and acknowledging the work of others through citing and referencing your sources.

Good academic practice

As with any writing task, you will need to review, edit and rewrite sections of your literature review. The Editing and proofreading page includes tips on how to do this and strategies for standing back and thinking about your structure and checking the flow of your argument.

Editing and proofreading

Guidance on literature searching from the University Library

The Academic Support Librarians have developed LibSmart I and II, Learn courses to help you develop and enhance your digital research skills and capabilities; from getting started with the Library to managing data for your dissertation.

Searching using the library’s DiscoverEd tool: DiscoverEd

Finding resources in your subject: Subject guides

The Academic Support Librarians also provide one-to-one appointments to help you develop your research strategies.

1 to 1 support for literature searching and systematic reviews

Advice to help you optimise use of Google Scholar, Google Books and Google for your research and study: Using Google

Managing and curating your references

A referencing management tool can help you to collect and organise and your source material to produce a bibliography or reference list.

Referencing and reference management

Information Services provide access to Cite them right online which is a guide to the main referencing systems and tells you how to reference just about any source (EASE log-in may be required).

Cite them right

Published study guides

There are a number of scholarship skills books and guides available which can help with writing a literature review. Our Resource List of study skills guides includes sections on Referencing, Dissertation and project writing and Literature reviews.

Study skills guides

What is a literature review?

If you have to write an undergraduate dissertation, you may be required to begin by writing a literature review. A literature review is a search and evaluation of the available literature in your given subject or chosen topic area. It documents the state of the art with respect to the subject or topic you are writing about.

A literature review has four main objectives:

A literature review shows your readers that you have an in-depth grasp of your subject; and that you understand where your own research fits into and adds to an existing body of agreed knowledge.

Here’s another way of describing those four main tasks. A literature review:

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How to Write a Literature Review

As every student knows, writing informative essay and research papers is an integral part of the educational program. You create a thesis, support it using valid sources, and formulate systematic ideas surrounding it. However, not all students know that they will also have to face another type of paper known as a Literature Review in college. Let's take a closer look at this with our custom essay writer .

Literature Review Definition

As this is a less common academic writing type, students often ask: "What is a literature review?" According to the definition, a literature review is a body of work that explores various publications within a specific subject area and sometimes within a set timeframe.

This type of writing requires you to read and analyze various sources that relate to the main subject and present each unique comprehension of the publications. Lastly, a literature review should combine a summary with a synthesis of the documents used. A summary is a brief overview of the important information in the publication; a synthesis is a re-organization of the information that gives the writing a new and unique meaning.

Typically, a literature review is a part of a larger paper, such as a thesis or dissertation. However, you may also be given it as a stand-alone assignment.

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The Purpose

The main purpose of a literature review is to summarize and synthesize the ideas created by previous authors without implementing personal opinions or other additional information.

However, a literature review objective is not just to list summaries of sources; rather, it is to notice a central trend or principle in all of the publications. Just like a research paper has a thesis that guides it on rails, a literature review has the main organizing principle (MOP). The goal of this type of academic writing is to identify the MOP and show how it exists in all of your supporting documents.

Why is a literature review important? The value of such work is explained by the following goals it pursues:

Here are some example topics for writing literature reviews:

How Long Is a Literature Review?

When facing the need to write a literature review, students tend to wonder, "how long should a literature review be?" In some cases, the length of your paper's body may be determined by your instructor. Be sure to read the guidelines carefully to learn what is expected from you.

Keeping your literature review around 15-30% of your entire paper is recommended if you haven't been provided with specific guidelines. To give you a rough idea, that is about 2-3 pages for a 15-page paper. In case you are writing a literature review as a stand-alone assignment, its length should be specified in the instructions provided.

Literature Review Format: APA, MLA, and Chicago

The essay format you use should adhere to the citation style preferred by your instructor. Seek clarification from your instructor for several other components as well to establish a desired literature review format:

If you want to format your paper in APA style, then follow these rules:

For MLA style text, apply the following guidelines:

Finally, if you are required to write a literature review in Chicago style, here are the key rules to follow:

Structure of a Literature Review

How to structure a literature review: Like many other types of academic writing, a literature review follows a typical intro-body-conclusion style with 5 paragraphs overall. Now, let’s look at each component of the basic literature review structure in detail:

Introduction

You should direct your reader(s) towards the MOP (main organizing principle). This means that your information must start from a broad perspective and gradually narrow down until it reaches your focal point.

Start by presenting your general concept (Corruption, for example). After the initial presentation, narrow your introduction's focus towards the MOP by mentioning the criteria you used to select the literature sources you have chosen (Macbeth, All the King's Men, and Animal Farm). Finally, the introduction will end with the presentation of your MOP that should directly link it to all three literature sources.

Body Paragraphs

Generally, each body paragraph will focus on a specific source of literature laid out in the essay's introduction. As each source has its own frame of reference for the MOP, it is crucial to structure the review in the most logically consistent way possible. This means the writing should be structured chronologically, thematically or methodologically.

Chronologically

Breaking down your sources based on their publication date is a solid way to keep a correct historical timeline. If applied properly, it can present the development of a certain concept over time and provide examples in the form of literature. However, sometimes there are better alternatives we can use to structure the body.

Thematically

Instead of taking the "timeline approach," another option can be looking at the link between your MOP and your sources. Sometimes, the main idea will just glare from a piece of literature. Other times, the author may have to seek examples to prove their point. An experienced writer will usually present their sources by order of strength. For example, in "To Kill A Mockingbird," the entire novel was centralized around racism; in "The Adventures of Huckleberry Finn," racism was one of many themes.

Methodologically

As made obvious by the terminology, this type of structuring focuses on the methods used to present the central concept. For example, in "1984", George Orwell uses the law-and-order approach and shows the dangers of a dystopia for a social species.

In "Frankenstein," Mary Shelley exposes the character's physical traits as repulsive and horrifying, forcing him to suffer in an isolated environment. By showcasing the various methods used to portray the MOP, the writer can compare them based on things like severity, ethicality, and overall impact.

After presenting your key findings in the body paragraphs, there are 3 final objectives to complete in the essay's conclusion. First, the author should summarize the findings they have made or found, in other words, and briefly answer the question: "What have you learned?"

After discussing that information, the next step is to present the significance of the information about our current world today. In other words, how can the reader take the information and apply it to today's society? From that point, we finish off with a breadcrumb trail.

As the author, you want to leave the readers' trail of thought within the actual essay topic. This provides them with a means of further investigation—meaning that the reader may consider where the discussion will go next.

Writing an Outline for a Literature Review

Students often underestimate the importance of planning the structure of their papers in advance. However, this is not a wise approach. Having a rough APA literature review outline (or other style outlines) will not only help you follow the right format and structure but will also make the writing process simpler and help ensure that you include all of the important information without missing anything.

How to write a literature review outline: As you already know from the Structure section of this guide, every part of your literature review performs its own important role. Therefore, you should create your outline while keeping the general introduction-body-conclusion structure in mind and ensuring that each section meets its own objectives. However, it is important to remember that a literature review outline is slightly different from outlines of other types of essays because it does not provide new information. Instead, it focuses on existing studies relevant to the main topic. ‍

Here is a literature review outline example on the subject of the Ebola virus to help you get it right:

Hopefully, this sample outline will help you to structure your own paper. However, if you feel like you need some more advice on how to organize your review, don’t hesitate to search for more literature review outline examples in APA or other styles on the Web, or simply ask our writers to get a dissertation help .

How to Write a Good Literature Review

Whether you are writing a literature review within the framework of a large research project (e.g. thesis, dissertation, or other) or as a stand-alone assignment, the approach you should take to writing generally remains the same.

Whether you are writing a literature review within the framework of a large research project (e.g., thesis, dissertation, or other) or as a stand-alone assignment, the approach you should take to writing generally remains the same.

Now, as you know about the general rules and have a basic literature review outline template, let's define the steps to take to handle this task right with our service:

Step 1: Identifying the Topic

This is probably the only matter you may approach differently depending on whether your literature review comes within a research paper or a separate assignment altogether. If you are creating a literature review as a part of another work, you need to search for literature related to your main research questions and problems. Respectively, if you are writing it as a stand-alone task, you will have to pick a relevant topic and central question upon which you will collect the literature. Earlier in this guide, we suggested some engaging topics to guide your search.

Step 2: Conducting Research

When you have a clearly defined topic, it is time to start collecting literature for your review. We recommend starting by compiling a list of relevant keywords related to your central question—to make the entire research process much simpler and help you find relevant publications faster.

When you have a list of keywords, use them to search for valid and relevant sources. At this point, be sure to use only trusted sources, such as ones from university libraries, online scientific databases, etc.

Once you have found some sources, be sure to define whether or not they are actually relevant to your topic and research question. To save time, you can read abstracts to get general ideas of what the papers are about instead of the whole thing.

Pro Tip: When you finally find a few valid publications, take a look at their bibliographies to discover other relevant sources as well.

Step 3: Assess and Prioritize Sources

Throughout your research, you will likely find plenty of relevant literature to include in your literature review. At this point, students often make the mistake of trying to fit all the collected sources into their reviews. Instead, we suggest looking at what you've collected once more, evaluating the available sources, and selecting the most relevant ones. You most likely won't be able to read everything you find on a given topic and then be able to synthesize all of the sources into a single literature review. That's why prioritizing them is important.

To evaluate which sources are worth including in your review, keep in mind the following criteria:

Furthermore, as you read the sources, don’t forget to take notes on everything you can incorporate into the review later. And be sure to get your citations in place early on. If you cite the selected sources at the initial stage, you will find it easier to create your annotated bibliography later on.

Step 4: Identify Relationships, Key Ideas, and Gaps

Before you can move on to outlining and writing your literature review, the final step is determining the relationships between the studies that already exist. Identifying the relationships will help you organize the existing knowledge, build a solid literature outline, and (if necessary) indicate your own research contribution to a specific field.

Some of the key points to keep an eye out for are:

Here are a few examples: Common trends may include a focus on specific groups of people across different studies. Most researchers may have increased interest in certain aspects of the topic regarding key themes. Contradictions may include some disagreement concerning the theories and outcomes of a study. And finally, gaps most often refer to a lack of research on certain aspects of a topic.

Step 5: Make an Outline

Although students tend to neglect this stage, outlining is one of the most important steps in writing every academic paper. This is the easiest way to organize the body of your text and ensure that you haven't missed anything important. Besides, having a rough idea of what you will write about in the paper will help you get it right faster and more easily. Earlier in this guide, we already discussed the basic structure of a literature review and gave you an example of a good outline. At this workflow stage, you can use all of the knowledge you've gained from us to build your own outline.

Step 6: Move on to Writing

Having found and created all of your sources, notes, citations, and a detailed outline, you can finally get to the writing part of the process. At this stage, all you need to do is follow the plan you've created and keep in mind the overall structure and format defined in your professor's instructions.

Step 7: Adding the Final Touches

Most students make a common mistake and skip the final stage of the process, which includes proofreading and editing. We recommend taking enough time for these steps to ensure that your work will be worth the highest score. Do not underestimate the importance of proofreading and editing, and allocate enough time for these steps.

Pro Tip: Before moving on to proofreading and editing, be sure to set your literature review aside for a day or two. This will give you a chance to take your mind off it and then get back to proofreading with a fresh perspective. This tip will ensure that you won't miss out on any gaps or errors that might be present in your text.

These steps will help you create a top-notch literature review with ease! Want to get more advice on how to handle this body of work? Here are the top 3 tips you need to keep in mind when writing a literature review:

1. Good Sources

When working on a literature review, the most important thing any writer should remember is to find the best possible sources for their MOP. This means that you should select and filter through about 5-10 different options while doing initial research.

The stronger a piece of literature showcases the central point, the better the quality of the entire review.

2. Synthesize The Literature

Make sure to structure the review in the most effective way possible, whether it be chronologically, thematically, or methodologically. Understand what exactly you would like to say, and structure the source comparison accordingly.

3. Avoid Generalizations

Remember that each piece of literature will approach the MOP from a different angle. As the author, make sure to present the contrasts in approaches clearly and don't include general statements that offer no value.

Literature Review Examples

You can find two well-written literature reviews by the EssayPro writing team below. They will help you understand what the final product of a literature review should ideally look like.

The first literature review compares monolingual and bilingual language acquisition skills and uses various sources to prove its point:

The second literature review compares the impact of fear and pain on a protagonist’s overall development in various settings:

Both reviews will help you sharpen your skills and provide good guidelines for writing high-quality papers.

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Systematic Review | Definition, Example & Guide

Published on June 15, 2022 by Shaun Turney . Revised on December 7, 2022.

A systematic review is a type of review that uses repeatable methods to find, select, and synthesize all available evidence. It answers a clearly formulated research question and explicitly states the methods used to arrive at the answer.

They answered the question “What is the effectiveness of probiotics in reducing eczema symptoms and improving quality of life in patients with eczema?”

In this context, a probiotic is a health product that contains live microorganisms and is taken by mouth. Eczema is a common skin condition that causes red, itchy skin.

What is a systematic review, systematic review vs. meta-analysis, systematic review vs. literature review, systematic review vs. scoping review, when to conduct a systematic review, pros and cons of systematic reviews, step-by-step example of a systematic review, frequently asked questions about systematic reviews.

A review is an overview of the research that’s already been completed on a topic.

What makes a systematic review different from other types of reviews is that the research methods are designed to reduce bias . The methods are repeatable, and the approach is formal and systematic:

Although multiple sets of guidelines exist, the Cochrane Handbook for Systematic Reviews is among the most widely used. It provides detailed guidelines on how to complete each step of the systematic review process.

Systematic reviews are most commonly used in medical and public health research, but they can also be found in other disciplines.

Systematic reviews typically answer their research question by synthesizing all available evidence and evaluating the quality of the evidence. Synthesizing means bringing together different information to tell a single, cohesive story. The synthesis can be narrative ( qualitative ), quantitative , or both.

Systematic reviews often quantitatively synthesize the evidence using a meta-analysis . A meta-analysis is a statistical analysis, not a type of review.

A meta-analysis is a technique to synthesize results from multiple studies. It’s a statistical analysis that combines the results of two or more studies, usually to estimate an effect size .

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A literature review is a type of review that uses a less systematic and formal approach than a systematic review. Typically, an expert in a topic will qualitatively summarize and evaluate previous work, without using a formal, explicit method.

Although literature reviews are often less time-consuming and can be insightful or helpful, they have a higher risk of bias and are less transparent than systematic reviews.

However, a scoping review isn’t a type of systematic review. The most important difference is the goal: rather than answering a specific question, a scoping review explores a topic. The researcher tries to identify the main concepts, theories, and evidence, as well as gaps in the current research.

Sometimes scoping reviews are an exploratory preparation step for a systematic review, and sometimes they are a standalone project.

A systematic review is a good choice of review if you want to answer a question about the effectiveness of an intervention , such as a medical treatment.

To conduct a systematic review, you’ll need the following:

A systematic review has many pros .

Systematic reviews also have a few cons .

The 7 steps for conducting a systematic review are explained with an example.

Step 1: Formulate a research question

Formulating the research question is probably the most important step of a systematic review. A clear research question will:

A good research question for a systematic review has four components, which you can remember with the acronym PICO :

You can rearrange these four components to write your research question:

What is the effectiveness of I versus C for O in P ?

Sometimes, you may want to include a fifth component, the type of study design . In this case, the acronym is PICOT .

Their research question was:

What is the effectiveness of probiotics versus no treatment, a placebo, or a non-probiotic treatment for reducing eczema symptoms and improving quality of life in patients with eczema?

Step 2: Develop a protocol

A protocol is a document that contains your research plan for the systematic review. This is an important step because having a plan allows you to work more efficiently and reduces bias.

Your protocol should include the following components:

If you’re a professional seeking to publish your review, it’s a good idea to bring together an advisory committee . This is a group of about six people who have experience in the topic you’re researching. They can help you make decisions about your protocol.

It’s highly recommended to register your protocol. Registering your protocol means submitting it to a database such as PROSPERO or ClinicalTrials.gov .

Step 3: Search for all relevant studies

Searching for relevant studies is the most time-consuming step of a systematic review.

To reduce bias, it’s important to search for relevant studies very thoroughly. Your strategy will depend on your field and your research question, but sources generally fall into these four categories:

At this stage of your review, you won’t read the articles yet. Simply save any potentially relevant citations using bibliographic software, such as Scribbr’s APA or MLA Generator .

Step 4: Apply the selection criteria

Applying the selection criteria is a three-person job. Two of you will independently read the studies and decide which to include in your review based on the selection criteria you established in your protocol . The third person’s job is to break any ties.

To increase inter-rater reliability , ensure that everyone thoroughly understands the selection criteria before you begin.

If you’re writing a systematic review as a student for an assignment, you might not have a team. In this case, you’ll have to apply the selection criteria on your own; you can mention this as a limitation in your paper’s discussion.

You should apply the selection criteria in two phases:

It’s very important to keep a meticulous record of why you included or excluded each article. When the selection process is complete, you can summarize what you did using a PRISMA flow diagram .

Next, Boyle and colleagues found the full texts for each of the remaining studies. Boyle and Tang read through the articles to decide if any more studies needed to be excluded based on the selection criteria.

When Boyle and Tang disagreed about whether a study should be excluded, they discussed it with Varigos until the three researchers came to an agreement.

Step 5: Extract the data

Extracting the data means collecting information from the selected studies in a systematic way. There are two types of information you need to collect from each study:

You should collect this information using forms. You can find sample forms in The Registry of Methods and Tools for Evidence-Informed Decision Making and the Grading of Recommendations, Assessment, Development and Evaluations Working Group .

Extracting the data is also a three-person job. Two people should do this step independently, and the third person will resolve any disagreements.

They also collected data about possible sources of bias, such as how the study participants were randomized into the control and treatment groups.

Step 6: Synthesize the data

Synthesizing the data means bringing together the information you collected into a single, cohesive story. There are two main approaches to synthesizing the data:

Generally, you should use both approaches together whenever possible. If you don’t have enough data, or the data from different studies aren’t comparable, then you can take just a narrative approach. However, you should justify why a quantitative approach wasn’t possible.

Boyle and colleagues also divided the studies into subgroups, such as studies about babies, children, and adults, and analyzed the effect sizes within each group.

Step 7: Write and publish a report

The purpose of writing a systematic review article is to share the answer to your research question and explain how you arrived at this answer.

Your article should include the following sections:

To verify that your report includes everything it needs, you can use the PRISMA checklist .

Once your report is written, you can publish it in a systematic review database, such as the Cochrane Database of Systematic Reviews , and/or in a peer-reviewed journal.

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

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

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

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

A systematic review is secondary research because it uses existing research. You don’t collect new data yourself.

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A literature review is an account of what has been published on a...

A literature review is an account of what has been published on a topic (in journal articles, conference proceedings, books and other relevant sources) by recognised researchers. Understanding the prior research on the topic of interest is the basis of most new research. Researchers must know what has been studied, found, discussed and recommended by others in related areas.

In this assignment you will identify and read published research literature on the topic: Use of affective computing in health applications and provide the following 2 deliverables that will synthesize what you have found to provide understanding about what is, and is not, known on the topic :

2. Produce a table with columns that contain the following information for each of the 10 papers:

3. Provide a literature review that synthesises the findings of these 10 papers. After reading each article, you should think about how they all fit together. Your review should be organised by concepts, such as findings, rather than by sources of information. Do not proceed through the articles one-by-one . In addition, you may choose to supplement these articles with a few articles from other sources that do not present the authors' own results if needed to help explain the topic.

Literature review formatting guidelines

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Essay Service Examples Business Leadership Development

Leadership Development: Definition and Literature Review

Introduction

The Learning and Development (L&D) umbrella has many areas that it covers from stress, employee engagement, and talent management to change management. However, this review will focus on the development of leaders through L&D practices and how these can be beneficial for Human Resources (HR) and an organization.

Leadership development is extremely important for any organization wishing to achieve long-term success. With this being said, nearly three-quarters of companies in England reported a deficit of leadership skills in 2012 according to BIS (Department for Business Innovation and Skills) which can lead to a high 56% failures in an organization. Therefore, proving that although improvements in L&D for leadership are made, there is still quite a substantial gap.

The aim of this essay, with the help of the literature on this topic, is to define leadership development as a concept with its processes and supposed outcomes and how this directly impacts Human Resource Management.

Definition of Leadership Development

Leadership development is one of those topics which does not have a set definition, but it is rather defined as it is perceived through the mind of the individual using it. Therefore, finding the right definition can be quite a challenge, however for the purpose of this essay Lynham’s (2000) definition will be used which says LD is a form of growth in the life cycle of a leader and helps the expansion of experience, knowledge, and skills.

When it comes to the methods used to implement LD, these can differ depending on the organization and its needs. According to a study from Megheirkouni (2016), there are four main methods: action learning, feedback methods, coaching/networking, and finally job rotation. These can disputably be categorized into two main sets one being collective LD which includes action learning sets and job rotation. Secondly, Leader Development methods such as feedback and coaching are ultimately more individualized in comparison to the first set (McGurk, 2010). The end goal of each method is eventually the same, to enable more effective organizational performance. The survival of any organization is extremely dependent on the ability to develop future leaders (Amaogh, F 2009).

Although, it is quite worrying that despite having studies and articles on the efficiency of methods for LD and the money invested by organizations which according to the CIPD is £3.2 billion annually, UK organizations still report a deficit of 72% of leadership skills (CIPD,2014).

What are the end goal and outcomes of Leadership Development?

The aim of an LD program is to give people the necessary attributes to be effective leader. Although, the goal will ultimately depend on what the organization wants to achieve through such programs whether that is to increase employee morale, increase retention, improve productivity or build better teams. Because of the outcomes LD brings, it is key for the company’s values, goals, and strategy to be aligned with the program created (Canals, 2014).

Leadership development literature

Most of the Leadership writing up until recently was dominated by style theories of leadership. However, given the new challenges organizations have to deal with in a time of such uncertainty and interdependency where rapid changes in the technology and economy areas are seen, can make such models quite incomplete (Clarke, 2012). These changes in the environment of an organization have shifted LD to move toward a more leader-centric view (Orvis and Ratwani, 2010). Therefore, although in the past a leader was seen as someone good at business, in today’s environment organizations demand many more skills for a leader such as managerial skills, excellent people skills, and creative ideas (Bolman and Deal, 2009). It is more than clear that, to meet such needs leaders need ongoing support and training and it is up to the company to identify the needs and create the best LD program.

Various models can be used for this purpose. Firstly, the Skills Gap Analysis model (SGI) which looks at the gap between existing skills and required skills while aligning these with the company’s needs and the job role. Obviously, the larger the gap is the longer the training is needed. The beauty of this model is that it aids organizations to focus on the areas with the highest priority while also estimating the time needed (Jean Brittain, 2016).

Secondly, the Training Needs Analysis (TNA) which identifies the strengths, weaknesses, opportunities, and threats to understand what is needed in a program (Moore and Dutton, 1978). Both models are used to identify the gap and therefore close this certain gap through learning and development.

However, both models lack continuity once the needs are established. They can be seen as a one-off analysis. According to PMC (Performance Management Consultants), there are seven factors that should be looked at for a successful LD program. The design of the program, good knowledge given to participants prior to starting the program, focus on behavior and not only training skills, management assessment objectives, flexible program design and process (to encourage dynamic), individual accountabilities for growth and lastly remembering that leadership effectiveness is directly related to the organization effectiveness (PMC, n.d.).

Therefore, it can be said that any model applied will need ongoing support to make sure the designed program is appropriate and effective. CIPD suggests that any TNA program should be used alongside an ongoing LNA program (Learning Needs Analysis for a continuous gathering of data and insights on operational demands for skills, new roles, changed roles, and employee capabilities (CIPD, 2020).

Edyn Group combines all the above models to create the most efficient development program for its leaders. The company analyzed the gap and training needs, created the program to align with its strategy and values, and now uses the LNA approach to continuously analyze the needs and get the best results.

Their leadership development program combines action learning, formal training, coaching, feedback, and stepping into the shoes of a higher manager approach. The company made sure the align its values, strategy, and objective with this program to ensure maximum efficiency. The company takes great pride in its L&D practices as well as the leadership development program which is proving to be very efficient according to their HR Director since most of the job promotions are usually done internally. Although, there are no reports to prove this.

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Organizing Your Social Sciences Research Paper

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.

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

Importance of a Good Literature Review

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

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

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

Types of Literature Reviews

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

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

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

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

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

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

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

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

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

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

Structure and Writing Style

I. Thinking About Your Literature Review

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

The critical evaluation of each work should consider :

II. Development of the Literature Review

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

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

III. Ways to Organize Your Literature Review

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

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

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

IV. Writing Your Literature Review

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

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

V. Common Mistakes to Avoid

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

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

Writing Tip

Break Out of Your Disciplinary Box!

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

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

Another Writing Tip

Don't Just Review for Content!

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

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

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

Yet Another Writing Tip

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

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

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

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Literature Review

What is a Literature Review?

As part of their research program, many students are instructed to perform a literature review, without always understanding what a literature review is.

This article is a part of the guide:

Browse Full Outline

Most are aware that it is a process of gathering information from other sources and documenting it, but few have any idea of how to evaluate the information, or how to present it.

A literature review can be a precursor to the introduction of a research paper , or it can be an entire paper in itself, acting as the first stage of large research projects and allowing the supervisor to ascertain that the student is on the correct path.

A literature review is a critical and in depth evaluation of previous research. It is a summary and synopsis of a particular area of research, allowing anybody reading the paper to establish why you are pursuing this particular research. A good literature review expands on the reasons behind selecting a particular research question.

What is a NOT a Literature Review?

A literature review is not simply a chronological catalog of all your sources, but an evaluation. It pulls the previous research together, and explains how it connects to the research proposed by the current paper. All sides of an argument must be clearly explained, to avoid bias, and areas of agreement and disagreement should be highlighted.

A literature review is likewise not a collection of quotes and paraphrasing from other sources. A good literature review should critically evaluate the quality and findings of the research.

A good literature review should avoid the temptation of stressing the importance of a particular research program. The fact that a researcher is undertaking the research program speaks for its importance, and an educated reader may well be insulted that they are not allowed to judge the importance for themselves. They want to be re-assured that it is a serious paper, not a pseudo-scientific sales advertisement.

Whilst some literature reviews can be presented in a chronological order, this is best avoided.

For example, a review of Victorian Age Physics may certainly present J.J. Thomson’s famous experiments in a chronological order. Otherwise, this is usually perceived as being a little lazy, and it is better to organize the review around ideas and individual points.

As a general rule, especially for a longer review, each paragraph should address one point, and present and evaluate all of the available evidence, from all possible differing points of view.

Conducting a Literature Review

Evaluating the credibility of sources is one of the most difficult aspects of a literature review, especially with the ease of finding information on the internet.

The only real way to evaluate is through experience, but there are luckily a few tricks for evaluating information quickly and accurately.

There is such a thing as too much information. Google does not distinguish or judge the quality of results, only how search engine friendly a paper is. This is why it is still good practice to begin research in an academic library. Any journals found there can be regarded as safe and credible.

The next stage is to use the internet, and this is where the difficulties begin. It’s challenging to judge the credibility of an online paper. It can be helpful to structure your internet research as if it were conducted on paper. Bookmark papers, which may be relevant, in one folder and make another subfolder for a ‘shortlist.’

The easiest way is to scan the work, using the abstract and introduction as guides. This helps to eliminate the non-relevant work and also some of the lower quality research. If it sets off alarm bells, there may be something wrong, and the paper is probably of a low quality. But be very careful not to fall into the trap of rejecting research just because it conflicts with your hypothesis . Failure to do this will completely invalidate the literature review and potentially undermine the research project. Any research that may be relevant should be moved to the shortlist folder.

The next stage is to critically evaluate the paper and decide if the research is sufficient quality. Think about it this way: the temptation is to try to include as many sources as possible, and assume that a long bibliography equates to a good paper. A smaller number of quality sources is far preferable than a long but irrelevant list.

Check into the credentials of any source which you rely on heavily for the literature review. The reputation of the University or organization is a factor, as is the experience of the researcher. If their name keeps cropping up, and they have written many papers, the source is probably OK.

Look for agreements. Good research should have been replicated by other independent researchers, with similar results, showing that the information is fairly safe to use. If the process is proving to be difficult (and in some fields like medicine and environmental research, there is a lot of poor science ) do not be afraid to ask a supervisor for advice. They should know some trustworthy sources to look at. It may be a little extra work for them, but there will be even more work if they have to tear apart a review because it is built on shaky evidence.

Conducting a good literature review takes patience and is a matter of practice. Take solace that even the best scientists can fall into the trap of using poor evidence. However, it’s all part of the scientific process . If your research program is well constructed, a less-than-perfect literature review will not affect the results.

Martyn Shuttleworth (Sep 16, 2009). What is a Literature Review?. Retrieved Mar 04, 2023 from Explorable.com: https://explorable.com/what-is-a-literature-review

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How To Structure Your Literature Review

3 options to help structure your chapter.

By: Amy Rommelspacher (PhD) | Reviewed By: Dr Eunice Rautenbach | November 2020

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:

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:

Example of literature review outline structure

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 .

Webinar - how to write a literature review

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.

The body section of your literature review is the where you'll present, analyse, evaluate and synthesise the existing research.

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 .

Adopting the chronological structure allows you to discuss the developments and debates in the field as they emerged 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.

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.

The thematic structure allows you to organise your literature by theme or category – e.g. by independent variables.

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

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.

The methodological structure allows you to organise your chapter by the analysis method used - e.g. qual, quant or mixed.

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:

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 theoretical framework for your dissertation or thesis, the conclusion section is a good place to present this.

In the conclusion section, you’ll need to present the key findings of your literature review and highlight the gaps that exist in the literature. Based on this, you'll need to make it clear what your study will add to the literature.

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:

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 (for free)

This post is part of our research writing mini-course, which covers everything you need to get started with your dissertation, thesis or research project.

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How To Read Journal Articles Quickly & Efficiently For Your Literature Review

22 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 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.

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?

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A systematic review of published literature on mosquito control action thresholds across the world

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

Affiliation Anastasia Mosquito Control District, St. Augustine, Florida, United States of America

Roles Data curation, Formal analysis, Investigation, Methodology, Validation, Visualization, Writing – original draft, Writing – review & editing

Roles Methodology, Writing – review & editing

Roles Funding acquisition, Resources, Writing – review & editing

Roles Conceptualization, Funding acquisition, Methodology, Project administration, Resources, Supervision, Writing – review & editing

* E-mail: [email protected]

This is an uncorrected proof.

Despite the use of numerous methods of control measures, mosquito populations and mosquito-borne diseases are still increasing globally. Evidence-based action thresholds to initiate or intensify control activities have been identified as essential in reducing mosquito populations to required levels at the correct/optimal time. This systematic review was conducted to identify different mosquito control action thresholds existing across the world and associated surveillance and implementation characteristics.

Methodology/Principal findings

Searches for literature published from 2010 up to 2021 were performed using two search engines, Google Scholar and PubMed Central, according to PRISMA guidelines. A set of inclusion/exclusion criteria were identified and of the 1,485 initial selections, only 87 were included in the final review. Thirty inclusions reported originally generated thresholds. Thirteen inclusions were with statistical models that seemed intended to be continuously utilized to test the exceedance of thresholds in a specific region. There was another set of 44 inclusions that solely mentioned previously generated thresholds. The inclusions with “epidemiological thresholds” outnumbered those with “entomological thresholds”. Most of the inclusions came from Asia and those thresholds were targeted toward Aedes and dengue control. Overall, mosquito counts (adult and larval) and climatic variables (temperature and rainfall) were the most used parameters in thresholds. The associated surveillance and implementation characteristics of the identified thresholds are discussed here.

Conclusions/Significance

The review identified 87 publications with different mosquito control thresholds developed across the world and published during the last decade. Associated surveillance and implementation characteristics will help organize surveillance systems targeting the development and implementation of action thresholds, as well as direct awareness towards already existing thresholds for those with programs lacking available resources for comprehensive surveillance systems. The findings of the review highlight data gaps and areas of focus to fill in the action threshold compartment of the IVM toolbox.

Author summary

Many different methods are used and new methods are evolving to control nuisance and vector mosquito populations across the world. Implementation of such control methods at the optimal time has been identified as critical to maintaining the populations below unacceptable levels. The establishment of evidenced-based action thresholds is thus encouraged to achieve maximum results under available resources. This review was conducted to identify different action thresholds published worldwide since 2010 and to understand the associated surveillance characteristics. Only 87 publications filtered through the initial database identification of 1,485 publications were included in the review. Thirty inclusions reported originally generated thresholds, 13 inclusions reported a statistical method with a computable action threshold model, and 44 inclusions mentioned only previously generated thresholds that were used in their study. Overall, the inclusions with thresholds that directly related to disease transmission conditions (“epidemiological thresholds”) outnumbered the inclusions with thresholds that directly related to mosquito abundance. The majority of the thresholds originated in Asia targeting dengue and dengue vectors. The review discusses the associated surveillance characteristics such as the possibility of using external data (previously recorded data), spatial and temporal variations in data used, and the importance of an adequate lead time to initiate control interventions that would help guide to plan better surveillance programs for the development of action thresholds.

Citation: Aryaprema VS, Steck MR, Peper ST, Xue R-d, Qualls WA (2023) A systematic review of published literature on mosquito control action thresholds across the world. PLoS Negl Trop Dis 17(3): e0011173. https://doi.org/10.1371/journal.pntd.0011173

Editor: Olaf Horstick, University of Heidelberg, GERMANY

Received: September 14, 2022; Accepted: February 14, 2023; Published: March 3, 2023

This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.

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

Funding: This research project was supported/funded by the Department of the Army, U.S. Army Contracting Command, Aberdeen Providing Ground, Natick, Contracting Division, Ft. Detrick, MD under Deploy War Fighter Protection (DWFP) program W911QY20110004 awarded to AMCD. 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.

Introduction

There are about 3,500 identified mosquito species in different geographic/climatic regions in the world. Some species act as human disease vectors while other species cause only biting nuisance problems. Vector-borne diseases account for more than 17% of all infectious diseases, causing more than 700,000 deaths annually [ 1 ]. More than 80% of the global population is at risk of vector-borne disease, with mosquito-borne diseases (MBDs) being the largest contributor to the human vector-borne disease burden [ 2 ]. MBDs such as dengue, Zika, chikungunya, West Nile virus (WNV), eastern equine encephalitis (EEE), western equine encephalitis (WEE), and malaria cause major public health issues across the world. The global burden of malaria has been estimated to be 219 million cases, with more than 400,000 deaths every year [ 1 ], and a reported 627,000 deaths in 2020 alone [ 3 ]. More than 3.9 billion people in over 129 countries are at risk of contracting dengue, with an estimated 96 million symptomatic cases and an estimated 40,000 deaths every year [ 1 ]. WNV is the most common MBD in the United States [ 4 ]. A total of 21,869 confirmed or probable cases of WNV disease were reported across all 50 states during 2009–2018 [ 5 ]. Chikungunya and Zika have caused the average yearly loss of over 106,000 and 44,000 disability-adjusted life years (DALYs) worldwide, respectively, between 2010 and 2019 [ 6 ]. There is a significant economic burden of MBDs as well. The direct global costs of malaria have been estimated to be at least US $12 billion per year [ 7 ]. The estimated total global cost of dengue was US $8.9 billion in 2013 [ 8 ]. The average cost of WNV in the United States was equivalent to an approximate average of $56 million per year during 1999–2012 [ 9 , 10 ]. There is no specific drug or vaccine available for MBDs such as dengue, chikungunya, etc. [ 11 , 12 ]. Control of vector populations is often the best way, if not the only way, to control the transmission of these diseases. On the other hand, although the major transmission of diseases such as malaria and lymphatic filariasis is controlled by mass drug administration (MDA), the vectors of the diseases are still a human nuisance. For all those reasons, mosquito control is still an integral constituent of the public health infrastructure of many countries.

There are many illustrious instances in history that mosquito control has effectively reduced disease burdens; reduction of malaria in the 1950s-1960s in some countries (in the Americas, Europe and Asia), dengue and yellow fever in the 1950s-1960s in the Americas, dengue in the 1970s-1980s in Singapore and dengue in the1980s-1990s in Cuba [ 13 ]. However, rapid and aggressive changes in mosquito population dynamics imposed by changing influential factors such as the environment, climate, geography, demographics and social culture, have been making mosquito control more challenging in the modern-globalized world. Development of resistance against all major classes of insecticides, and a shortage of effective insecticide innovation, registration, and supply have become another threat to mosquito control [ 14 ]. Compounding all those complexities, mosquito control is often reactive [ 14 ] as it is implemented only in direct response to already increased risk based on vector or disease surveillance results in the present time [ 15 ]. The effects of such control programs would be too late to prevent undesirable levels of human-mosquito contact, and thus the potential for disease explosions. One of the key elements lacking in many mosquito control programs is the use of reliable preemptive indicators to initiate proactive control operations before mosquito populations or disease risks are elevated to undesirable levels. It is widely accepted that Integrated Vector Management (IVM) and Integrated Mosquito Management (IMM) programs that make reliable evidence-based control decisions and that utilize appropriate control tools, can effectively reduce mosquito abundance and disease risk [ 16 ]. Therefore, early warning systems with evidence-based action thresholds that trigger interventions at the optimal time are now becoming critical in operational mosquito control. In addition to being more effective in controlling mosquito populations, such systems would help ensure prioritized allocation of resources, manage insecticide resistance, and hence help manage overall program logistics.

Understanding the relationship between influential factors and the dynamics of mosquito populations and disease transmission through properly planned surveillance systems is fundamental in establishing evidence-based mosquito control action thresholds. The structure of surveillance systems and therefore the data collected by different mosquito control programs are widely varied due to differences in geography, climate, economy, and other logistic factors. Therefore, there could be different action thresholds for the same species or species groups in different geographic/climatic regions as well as in the same region. Given the critical importance of the use of action thresholds in mosquito control, we systematically reviewed the published literature to identify different mosquito control action thresholds existing across the world and associated surveillance and implementation characteristics. The findings will give insights to mosquito control program managers and others, who anticipate developing and establishing their own action thresholds, to plan appropriate surveillance programs. Otherwise, this review will be helpful for those that wish to utilize already developed action thresholds due to the inability to establish comprehensive surveillance systems, especially the routine collection of mosquito data.

The systematic review was conducted following the PRISMA 2020 guidelines [ 17 ]. A protocol was prepared and agreed upon by all authors. An appropriate literature search was conducted from March 2020 to July 2021 using two main public search engines, Google Scholar (GS) and PubMed Central (PMC). The search terms were chosen to encompass a broad range of major vector species, diseases, surveillance/threshold measures, and analogies for “threshold”. Primary search queries involved various combinations of key terms using (i) major vector mosquito genera (“ Anopheles ”, “ Aedes ”, “ Culex ”), followed by AND “mosquito” AND “[] threshold” ([]: risk, epidemic, disease, tolerance, action), (ii) [(disease name) control” (disease name: malaria, dengue, zika, chikungunya, West Nile virus) followed by AND “threshold” /”action threshold”. (iii) “mosquito control”, “mosquito abundance”, “evidence based” with “threshold”/“action threshold”/”tolerance threshold”, and (iv) “control” followed by AND “mosquito” AND some analogous “threshold” terms that were discovered at the initial planning and search stage such as “trigger”/“warning”. For GS searches, all key terms were put in quotation marks to ensure a feasible number of search results (i.e. no more than several hundred). Quotation marks were also used for PMC searches; however, several PMC searches were conducted without quotation marks to instead broaden the search net after receiving any output of “no results found”. Searches were independently conducted by two human reviewers (VSA, MRS) with separate search terms until all planned combinations were exhausted and no new links appeared on the first listed page of results, considered as our point of saturation. Search process and the inclusion/exclusion criteria are summarized in Fig 1 . Any disagreement at each stage was resolved by in-person discussions.

https://doi.org/10.1371/journal.pntd.0011173.g001

Direct control thresholds/operational targets to keep mosquito populations below unaccepted levels of biting nuisance or disease transmission, risk level indicators to guide mosquito control, defined pest levels, and indicators of seasonal mosquito activity were identified as mosquito control action thresholds in this review. Retrieved publications were divided into three inclusion categories to reflect the various circumstances an action threshold was implicated in them; (i) “generated thresholds”- publications with an originally generated action threshold, (ii) “generated-models”—publications with a statistical model that involved a computable trigger/risk assessment with input of dynamic data to indicate if the area under study is over a threshold or within a risk level, and (iii) “mentioned thresholds”–publications with clear mention of a previously generated action threshold/s when the cross-references cited in them were not eligible to be included in (i) or (ii). Within those three categories, two types of action thresholds were identified: “entomological thresholds”- the threshold directly indicates mosquito abundance without connecting it to an epidemiological indication (EI) of a disease (could be associated with either vectors or non-vector nuisance mosquitoes), and “epidemiological thresholds”- the threshold is directly related to an EI (transmission, outbreak, epidemic). Calculation methods of EIs greatly differed between publications, some calling for flexibility dependent on the choices of local government bodies, others using specific calculations. Definitions for EI that were defined and/or justified in publications are included alongside action threshold descriptions in supplemental data tables ( S1 , S2 and S3 Tables). Other data points extracted during the full-text screening included publication type (scientific journal, guidelines, theses/dissertations, etc., geographic origin of the threshold/s (continent, climatic region), spatial unit of analysis (study area size), spatial unit of implementation (suggested/planned area associated with threshold), origin of data (self-sampled data, previously recorded data), time span of used data, data frequency (temporal resolution used data), mosquito species in concern, disease in concern, variables used in the threshold, types of mosquito data (e.g. larval indices, adult trap counts), data frequency, associated proactive lead time from the exceedance of the threshold to its indication, self-assessment of the validity of the threshold, and intended use of the threshold.

GS and PMC produced 1,559 and 2,322 search results, respectively, between the two human reviewers and search query combinations. The quantitative value of unique search results was revealed by the removal of replicates through the compilation of all citations from recorded search queries. Replicate overlap between the two search engines was minimal and the total number of initial unique search manually screened for abstracts was 1,485. The abstract screening reduced the initial unique 1,485 publications to 233 publications for the next screening (i.e., reading the full text) and data extraction process. Combined with the 4 cross-references of “mentioned thresholds” which met all the inclusion criteria, the final screening identified 87 publications to be included in the review (inclusions, hereafter) ( Fig 2 ).

https://doi.org/10.1371/journal.pntd.0011173.g002

There were 30 inclusions with “generated thresholds” (hereafter GTs, S1 Table ) [ 18 – 47 ], 13 inclusions with “generated-models” (hereafter GMs, S2 Table ) [ 48 – 60 ], and 44 inclusions with “mentioned thresholds” (hereafter MTs, S3 Table ) [ 61 – 104 ]. Some of the MTs were evidence-based generations of previously (before 2010) published studies while a few did not discuss how they were generated. As per the respective inclusions, they were still in use and therefore, worthwhile looking into available relevant data points. Outcomes of extracted data points were presented as percentages of all inclusions or GTs/GMs and MTs as appropriate.

1. Publication type

The majority of inclusions were retrieved from scientific journals (89.7% [78/87]) [18–47 (GT); [ 48 – 59 ] (GM); 61–96 (MT)] and there were three program guidelines (3.4% [3/87]) [97–99 (MT)], three technical reports (3.4% [3/87]) [100–102 (MT)], two conference proceedings (2.3% [2/87]) [103,104 (MT)], and one thesis/dissertation (1.1% (1/87)] [60 (GM)].

2. Geographic origin of the threshold

Inclusions with thresholds were identified in broadly defined two climatic regions: tropical/sub-tropical (71.3% [62/87]) [18–44 (GT);49,51–60 (GM); 61,64,65,67,69,71,75,76,77,80,82,83,85,87–90, 92–98 (MT)], and temperate (24% [21/87]) [45–47 (GT); 48,50 (GM); 62,63,66,68,70,72–74,78,86,99–104 (MT)]. There were a few inclusions (5.7% [5/87]) that reported (i) a threshold developed from data of different climatic regions [48 (GM)], (ii) different thresholds from different regions [81 (MT)], and (iii) those that did not specify the geographic origin of the threshold [79,84,91 (MT)].

The highest number of inclusions were from Asia (36.7% [32/87]) [22–27,29,30,33–38,41–44 (GT); 56–59 (GM); 71,75,77,82,85,87,89,90,93,98 (MT)], followed by North America (27.5% [24/87]) [28,45,46 (GT); 48–51 (GM); 61–63,68,70,72,74,78,80,83,86,92,96,97,99,103,104 (MT)], and South America (14% [12/87]) [19,40 (GT); 52–55 (GM); 64,65,67,69,75,81 (MT)].

3. Threshold types and epidemiological indication (EI)

The majority of inclusions reported “epidemiological thresholds” (77% [67/87]) [20–44 (GT); 49–60 (GM); 61–65,67,69,71,73,75,76,77,79,81–84,87–91,93–95,97,98,101–104 (MT)], while only 19 inclusions reported “entomological thresholds” (21.8% [19/87]) [18,19,45–47 (GT); 48 (GM); 66,68,70,72,74,78,80,85,83,86,96,99,100 (MT)]. There was one inclusion that reported both types (1.1% [1/87]) [92 (MT)].

Disease transmission was the expected EI of most of the “epidemiological threshold” inclusions (56% [38/68]) [27–35,38,39,42–44 (GT); 50,55,58,59 (GM); 62,63,65,67,69,73,75,76,79,81,87,89,90–95,98,101 (MT)] followed by epidemics (28% [19/68]) [20,21,24,41 (GT); 49,52–54,57 (GM); 48,71,77,82,84,88,97,102–104 (MT)] and outbreaks (14.7% [10/68]) [22,23,26,36,39,40 (GT); 51,56,60 (GM); 64 (MT)]. There was one inclusion that reported thresholds for both disease transmission and outbreaks [25 (GT)]. However, it is noteworthy that the definition of the EI of those thresholds could be greatly varied between different inclusions.

4. Targeted mosquito species and diseases

Aedes aegypti Linn. and/or Aedes albopictus Skuse were the most reported mosquito species (80.5% [71/87]) [18,19,21–28,30,31,33–36,38–44,47 (GT); 49–60 GM), 61–64,66–71,73,75–95,98,99,102 (MT)]. Twelve inclusions mentioned Culex species (13.8% [12/87]) [20,29,45,46 (GT); 48 (GM); 63,72,74,97,100,103,104 (MT)] and two inclusions reported thresholds for Anopheles species (2.3% [2/87]) (32 GT); 101 (MT)]. Other Aedes species were considered in five inclusions (5.7% [5/87]) [20 (GT); 48 (GM); 79,94,100 (MT)]. There were four inclusions (4.6% [4/87]), three “epidemiological thresholds” [37 (GT)]; 62,65 (MT)] and one “entomological threshold” [96 (MT)] that did not specify any mosquito species.

In parallel with the most reported mosquito species, dengue was the most reported disease (61% [53/87]) [19,22–27,30,33–36,38–44 (GT); 51–60 (GM); 61,64,65,67,69,71,73,75,-77,79,82,84,87–91,93–95,98,99,102 (MT)] followed by chikungunya (10.3% [9/87]) [21,28,31 (GT); 73,81,83,95,99,102 (GM)] and Zika (9.2% [8/87]) [49,50 (GM); 80,81,88,92,95,102 (MT)]. There were eight inclusions for WNV (9.2% [8/87]) (45,46 (GT); 62,63,74,97,103,104 (MT)], three for malaria (3.4% [3/87]) [32,37 (GT); 101 (MT)], two for yellow fever (2.3% [2/87]) 79,91 (MT)], two for Ross river virus (RRV) (2.3% [2/87]) [20 (GT); 100 (MT)], one for Japanese encephalitis (1.1% [1/87]) [29 (GT)], and one for other viral diseases (1.1% [1/87]) [100 (MT)]. Eleven “entomological threshold” inclusions did not specify any disease (12.6% [11/87]) [18,47 (GT); 48 (GM); 66,68,70,72,78,85,86,96 (MT)].

5. Variables used in action thresholds/model inputs

Different studies have used different variables to generate thresholds. Mosquito data were the most used (63.2% [55/87]) [21–26,28,30,31,35,36,38,41,43,44 (GT); 55,59 (GM); 61,64,66–89,91–96,98–101,103,104 (MT)] and most of those thresholds were for Ae . aegypti and/or Ae . albopictus for the control of dengue (63.6% [35/55]) [22–26,30,35,36,38,41,43,44 (GT); 55,59 (GM); 61,64,67,69,71,73,75–77,79,82,84,87–89,91,93,94,95,98,99 (MT)], chikungunya (14.5% [8/55]) [21,28,31 (GT); 73,81,83,95,99 (MT)], Zika (9% [5/55]) [ 80 , 81 , 88 , 92 , 95 ], yellow fever (3.6% [2/55]) [ 79 , 91 ]. Some of the MTs used mosquito data for thresholds of WNV (5.5% [3/55]) [ 74 , 103 , 104 ], malaria (1.8% [1/55]) [ 101 ], RRV and other diseases (1.8%) [1/55]) [ 100 ]. Larval indices (Stegomyia indices- Breteau index, house index, and container index) were the most used mosquito data variable (41.8% [23/55]) [23–26,30,35,36,41,43 (GT); 61,64,71,77,79,82,84,87,88,89,91,92,94,95 (MT)] followed by adult mosquito trap counts (31% [17/55]) [28,44 (GT); 66–68,70,78,80,81,83,86,96,99–101,103,104 (MT)]. The presence of larvae (9% [5/55]) [38 (GT); 59 (GM); 72,74,92 (MT)], pupal index (3.6% [2/55]) [ 69 , 75 ], presence of eggs/egg density (11% [6/55]) [21,31 (GT); 73,76,85,93 (MT)], biting density (1.8% [1/55]) [27 (GT)], resting density (1.8% [1/55]) [24 (GT)], and virus screening (1.8% [1/55]) [55 (GM)] were the other mosquito data variables used. Two other GMs [ 48 , 58 ] used mosquito data only for the development of their climate-based risk prediction models while all other GMs entirely disregarded mosquitoes as either model parameters or output in the development of models.

All the GT “entomological thresholds” and all except Ong et al. [ 59 ] of GMs primarily relied on climate variables while none of the MTs reported the use of climate data. Thirty percent of all inclusions (30% [26/87]) [18–20,27,29,32–34,37,39,42,45–47 (GT); 48–58,60 (GM)] used climate variables, mainly temperature (88.5% [23/26]) [18,19,25,27,29,33,39,42,45–47 (GT); 48–58,60 (GM)] and rainfall (53.8% [14/26]) [20,32,34,37,45,46 (GT); 48,52–54,56–58,60 (GM)]. One of those studies [25 (GT)] reported thresholds with several climatic variables; temperature, relative humidity (RH), wind speed, and sunshine duration, and another [57 (GM)] used RH in the final model.

Fifteen of all inclusions (17.2% [15/87]) [40 (GT); 49, 51–57,59,60 (GM); 63,65,90,102 (MT)] used human case data in their thresholds/model inputs with indications of preemptive use of the threshold.

In addition, two inclusions discussed the use of a special index of several variables [63,97 (MT)], and another one used the number of dead birds [62 (MT)]. Geographic location was important in several GMs; Foley and Pecor [ 50 ] relied on geo-referencing US military facilities onto published vector and virus habitat suitability maps, while Lowes et al. [ 52 – 54 ] compartmentalized risk to micro-region resolution in Brazil with environmental variables of biome and altitude. One GM that involved spatial environmental parameters in creating risk maps used vegetation, connectivity, and residential coverage [ 49 ] while another used terrain height [ 58 ]. Zhang et al. [ 57 ] stood out because the climate and epidemiological surveillance parameters of one city were modeled to predict the extension of disease transmission risk to a neighboring city. There was a unique GM that approached utilizing social media platform data -Twitter tweets [ 55 ].

6. Statistical procedures used in GMs

All GMs incorporated a threshold as the dividing value for a binary classification system, i.e., the model output—estimated mosquito count [ 48 ], estimated disease cases [ 51 – 54 , 56 , 57 , 59 , 60 ], probability of epidemic/outbreak [ 49 ], probability of exceeding a defined number of disease cases [ 51 – 54 ] that will trigger a warning if the estimate exceeds the binary divider value and thus the area enters a higher category of risk. Some studies involved two or more binary classification schemes that led to multiple risk warning categories (38.5% [5/13]) [ 50 , 52 – 54 , 59 ]. Most studies (61.5% [8/13]) directly stated a specific number or rate of disease cases as their chosen EI [ 51 – 57 , 60 ].

The models vary in complexity and the majority (69.2% [9/13]) involved a generalized linear model or generalized linear mixed model [ 48 , 51 – 58 ]. A common paradigm was to develop a model that predicted the Y% probability of exceeding the X number of disease cases (i.e., EI). Comparatively, Foley and Pecor [ 50 ] created an excel spreadsheet calculator that entailed a monthly review. It ranked Zika transmission risk based on the temperature and habitat suitability of virus and mosquito vectors, meaning four separate binary classifications had to be performed to determine the (forecast) final risk code status for the upcoming month. Other studies utilized Random Forest machine learning [ 59 , 60 ] or developed a risk-assessment framework involving stochastic simulations [ 49 ]. A series of inclusions of the same author group detailed the advancing development of a Bayesian spatio-temporal hierarchical model to predict dengue risk in Brazil by microregion [ 52 , 53 ], later tailored to proactively forecast risk for the 2014 World Cup [ 54 ], and finally validated after the tournament’s conclusion [ 64 ]. The advanced model was also implemented for the island country of Barbados [ 51 ]. Interestingly, the advanced model incorporated a pre-defined threshold of cases and a probability threshold that could be optimized to reduce false warnings while aiding policymakers to effectively allocate control resources and activities, a priority also discussed in another GM [ 49 ].

7. Surveillance and implementation characteristics

Associated surveillance and implementation characteristics reported by GTs/GMs (n = 43) were analyzed. Analysis of MT data were included whenever available. Species-wise analysis was not appropriate due to the very low number of inclusions of other species except Ae . aegypti/Ae . albopictus (80% [36/43]). Hence the analysis was conducted collectively for all inclusions.

a. The origin and time span of data.

The origin of data used to generate action thresholds varied in different inclusions. All except one inclusion (97.7% [42/43]) used external data sources (previously recorded data) for at least one variable used. Thirty studies (69.8% [30/43]) relied exclusively on external data sources [20, 22–24,27,29,30,32–34,37–40,42–46 (GT); 49–54, 56–60 (GM)] while 13 studies (30.2% [13/43]) [18,21,25,26,28,31,35,36,40,41,47 (GT); 48,55 (GM)] collected self-sampled data. All the self-sampled data were on mosquito data of which 3 collected virus screening data (23% [3/13]) [28,47 (GT); 55 (GM)] and one collected climate data (7.7% [1/13]) [47 (GT)] as well. External data were retrieved on human cases (67.4% [29/43]) [20,23–27,29,30,32,33–39,41,42,44 (GT); 49,51–59 (GM)], climate variables (65% [28/43]) [18–21,24,27–34,37,39,45,46 (GT); 48,50–58,60 (GM)], mosquito data (30.2% [13/43]) [22–24,35,38,41,42,44–46 (GT); 55,58,59 (GM)], and other data such as demographic data, spatial data, tweets (37.2% [10/43]) [49–51,53–55,57–60 (GM)].

More than half of those inclusions (52.2% [23/43]) used >5 years’ data [20,24,27,29–33,35,38–42 (GT); 49,51–54,56,57,59,60 (GM)] with half of them (50% [12/24]) used >10 years’ data [20,29,30,32,38,40 (GT); 49,51,54,56,57,60 (GM)]. Seven studies used 2–5 years’ data (16.3% [7/43]) [34,36,37,46,47 (GT); 48,54 (GM)] and 12 studies (28% [12/43] used data spanning less than two years [18,19,21–23,26,28,31,43,44 (GT); 50,58 (GM)]. The majority of MTs originated before 2010 (52.3% [23/44]) [ 61 – 65 , 67 – 69 , 71 , 75 , 76 , 79 , 81 , 82 , 84 , 87 , 88 , 89 , 91 – 93 , 95 , 100 , 104 ] while the time of origination was not clear in other MTs.

b. Data frequency.

The majority of GTs and GMs that used mosquito data relied mostly on daily/weekly data (35.3% [6/17]) [21,23,28,31,44 (GT); 55 (GM)] or bi-weekly/monthly data (35.3% [6/17]) [24,25,30,35,36,41 (GT)]. Two inclusions used yearly data (11.8% [2/17]) [38 (GT); 59 (GM)], one inclusion used only one-time data to generate action thresholds for two city parks (6% [1/17]) [22 (GT)], and there were two inclusions with no clear mention of the data frequency (11.8% [2/17]) [26,43 (GT)]. Inclusions that used climatic variables relied mostly on daily/weekly data (61.5% [16/26]) [18,19,27,33,34,42,45–47 (GT); 48,49,55–58,60 (GM)] over monthly data (38.5% [10/26]) [20,29,32,37,39 (GT); 50–54 (GM)]. Daily/weekly data frequency was the most used (50% [5/10]) [49,55–57,60 (GM)] in GTs and GMs that used human case data.

c. Spatial unit of analysis and intended spatial implementation of thresholds.

The spatial assessment level (data collection units) of GTs/GMs varied from 1x1 km grid cells in neighborhoods to district blocks, to represent the same or larger spatial units of analysis (study area). Town/city (28% [12/43]) [21,24,27,30,33,40,44 (GT);55–57,59,60 (GM)], country (14% [6/43]) [29,32,42 (GT); 51,52,54 (GM)], municipality (9.3% [4/43]) [18,25,26,47 (GT)], district (9.3% [4/43]) [23,36,37,43 (GT)], and region (9.3% [4/43]) [34,45,46 (GT): 53 (GM)] were the most studied spatial units of analysis.

Those thresholds were generated with the intention of implementing them in the study area itself (69.7% [30/43]) [22,23,25–27,29,31–34,36–46 (GT); 49–51,54,56–60 (GM)] or a larger area including the study area (28% [12/43]) [18,19,21,24,28,30,35,47 (GT); 48,52,53,55 (GM)]. Only one inclusion intended to implement the threshold in a smaller area than the study area (2.3% [1/43]) [20 (GT)].

More than half of the MTs (66% [29/44]) [ 61 – 65 , 66 – 68 , 70 , 72 – 74 , 76 – 78 , 80 , 83 , 85 – 87 , 89 , 90 , 93 , 96 , 97 , 100 , 101 , 103 , 104 ] mentioned thresholds that originated in the same country or at least in the same region [ 102 ] and of these, nine originated from the same individual state within the United States [ 63 , 68 , 72 , 74 , 78 , 86 , 96 , 97 , 103 ]. Eight inclusions (18.2% [8/44]) [ 66 , 78 , 86 , 90 , 96 , 100 – 102 ] mentioned thresholds that originated from the same program. One inclusion (2.3% [1/44]) [ 75 ] mentioned a threshold with a different country origin while four inclusions (9% [4/44]) [ 69 , 88 , 92 , 94 ] mentioned thresholds from different continental regions. Only one inclusion (2.3% [1/44]) [ 81 ] mentioned different thresholds either with the same country origin or different country origin and one inclusion (2.3% [1/44]) [ 98 ] did not cite a cross-reference or mention the origin of the mentioned threshold. Globally recognized thresholds were mentioned in six inclusions (11.4% [5/44]) [ 71 , 79 , 84 , 91 , 95 ].

d. Lead time and validation of the threshold.

The most reported lead time that used mosquito data (41.2% [7/17]) [24,30,35,36,41,44 (GT); 55 (GM)], as well as climate data (46.2% [12/26]) [20,27,33,37,39,42,45 (GT); 51,54,55,57,60 (GM)], was 1–3 months. Three inclusions with mosquito data (11.8% [2/17]) [24 (GT); 55 (GM)] and three inclusions with climate data (11.5% [3/26]) [18 (GT); 55,58 (GM)] reported 1–3 weeks lead time. Using climate data, four other inclusions (15.4% [4/26]) [52,53,56,57 (GM)] reported a lead time of more than 3 months while Smith et al. [32 (GT)] reported a different lead time. However, ten mosquito data inclusions (58.8% [10/17]) [21–23,25,26,28,31,38,43 (GT); 59 (GM)] did not report any lead time. Notably, several GMs utilized or made suggestions to utilize a specific climate forecasting resource to optimize the proactive lead time for control interventions [ 50 – 54 ]. Others developed models that used climate data at time points prior to the time point of model predictions, although lead-time would only be as long as the shortest time-lagged variable [ 49 , 56 , 57 ].

Most inclusions (60.5% [26/43]) analyzed performance statistics for GT/GM validation purposes. Of those, the majority used only training data (57.7% [15/26]) [20,23–25,27,31,32,38,40,41,45 (GT); 51,52,54,57 (GM)] while only eleven inclusions (42.3% [11/26]) [21,36,43,46 (GT); 48,53,55,56,58–60 (GM)] used testing data worth 6 weeks to 5 years. Of all GTs/GMs seventeen (39.5% [17/43]) [18,19,22,26,28–30,33–35,37,39,42,44,47 (GT); 49,50 (GM)] did not report on validation of GT/GM performance. However, some of those GTs were validated in subsequent studies which were included in the review as MTs [ 61 – 65 ].

8. Intended use of the threshold

Two broad categories of intended uses were identified from the inclusions. Direct intentions included those that stated direct utility for initiating mosquito control operations by setting an operational target threshold to keep populations below unaccepted levels of biting nuisance/disease transmission and others that determined different risk levels to guide a mosquito control response and/or effective resource allocation. Indirect intentions involved inclusions that mentioned mosquito/vector control at least once but discussed the utility of the action threshold within the wider expanse of a public health response without a specific discussion of focused implementation in mosquito control.

The majority of inclusions (88.5% [77/87]) [18–23,25–28,31,34–36,38,40–47 (GT); 48,50,52–60 (GM); 61–64, 66–104 (MT)] indicated the direct use of the threshold in mosquito control. Seven inclusions (11.5% [10/87]) 24,29,30,32,33,37,39 (GT); 49,51 (GM); 65 (MT)] intended to use the thresholds in initiating or guiding public health responses to control disease spread indirectly indicating their use in mosquito control.

Although the establishment of action thresholds has become critically important to achieve the maximum cost-effective benefit of mosquito control interventions, there is no formulated guidelines on the development of thresholds in different environmental settings. This review attempted to identify publications with mosquito control action thresholds across the world during the last 10 years and the basic surveillance and implementation characteristics associated with those thresholds. We hope the findings of the review will help guide mosquito control program managers and any other personnel who are interested in developing/using action thresholds to be included in their programs.

The 87 inclusions of the review were categorized into three broad categories; originally generated thresholds, generated models, and mention of previously generated thresholds. General information and surveillance/implementation characteristics of the three categories were examined to understand the structure of their surveillance systems.

More than 90% of the inclusions were from scientific journals/conference proceedings indicating the scientific/academic interest on developing action thresholds. However, the very low number (6.8%) of inclusions from program guidelines/technical reports could not be considered due to the scarcity of thresholds being used practically in mosquito control programs. There could be established thresholds that have already been in the specific IMM toolboxes of mosquito control programs but not disseminated in publications or in publications that fall into our inclusion criteria. We have planned and already initiated to identify those action thresholds through individual discussions with program managers/authorities in another study.

Overall, 77% of identified thresholds were “epidemiological thresholds and thus, indicate that the need to establish mosquito control action thresholds has been driven mainly by the transmission dynamics of mosquito-borne diseases rather than by biting nuisance. The majority of epidemiological thresholds here were to indicate transmission of disease although there is a chance of overlapping as the used epidemiological indication terms were not based on strict definitions. It is evidence for the need of more promising proactive mosquito control as discussed by Eisen et al. [ 105 ] rather than waiting for the transmission to transform into outbreaks or epidemics. Although mosquitoes are widely distributed in different climatic regions in the world, they thrive in regions with warm temperatures, humid conditions, and high rainfall, and thus tropical and sub-tropical areas are ideal for their survival [ 106 ]. Most of the identified action thresholds (>70%) being generated in tropical and sub-tropical climatic regions indicate their relevance to the burden of mosquitoes and mosquito-borne diseases in those regions, compared to others. The fact that the highest number of thresholds, were originated in Asia and associated most with dengue and dengue vectors should have a link with recent increases in the incidences of major dengue outbreaks and epidemics reported mainly in the Asian region [ 107 , 108 ]. However, recent studies show the geographical distribution of Ae . aegypti and Ae . albopictus is now extensive in all human inhabited continents; Europe and North America [ 109 ], South America [ 110 ], Oceania [ 111 , 112 ], and Africa [ 113 ].

Overall, the majority of inclusions have used mosquito data in thresholds. However, some of the recently developed entomological thresholds have moved on to use climate data, mainly temperature, rather than using mosquito data itself as done previously (before 2010). It is a good step forward to proactively inform the need to initiate mosquito control and thus help bring about more effective prevention of unacceptable levels of mosquito abundance. Despite controversy on the association with the number of disease cases [ 36 , 41 , 114 – 122 ], the majority of epidemiological thresholds for dengue and chikungunya were generated using Stegomyia larval indices.

The data collection duration is a substantial characteristic in the process of action threshold development. A sufficient time span would allow identifying any time sensitive variations in the identified correlations, thus in the generated action thresholds. Therefore, thresholds developed using historic data would be more reliable than those generated using only current data or one-time data. Davis et al. [ 123 ] suggested the inconsistent reliability and questionable validity of the thresholds generated in the study by using <3 years data would be refined with additional years of data. Using <5 years’ historic data in their study, Bowman et al. [ 124 ] suggested that data of a greater number of historic years would have generated more reliable results. Other studies which reported alert thresholds for malaria based on disease case numbers discuss the need of at least 5 years of historical data [ 125 , 126 ]. The majority of studies reviewed here being used carried out over more than 5 years have allowed the possible temporal variations to be considered and compromised. Studies conducted in less than 2 years might not be able to catch time sensitive variations in the variables used thus making the threshold less reliable to use over the years. Likewise, mosquito abundance and disease transmission dynamics may change over time due to many reasons such as environmental/climatic changes, human mobility, etc. Most of the “mentioned thresholds” being developed more than ten years ago might need assessments and necessary updates before using in current mosquito control programs. Notably, almost all identified studies have used external data sources mainly from relevant government entities to generate thresholds. The use of external data sources requires careful selection and matching of data in the temporal and spatial units in concern to generate reliable thresholds. The distribution of mosquitoes and hence the mosquito-borne diseases are clustered in nature based on different ecological niches they use [ 127 ]. However, the demarcation of spatial units of those studies is based on man-made administrative boundaries rather than on ecological or geographical determinants. Therefore, the use of a particular action threshold in the spatial unit of its origin is more reasonable than using it in an area with different geographical, climatic, environmental, demographic, socio-economic, and other relevant characteristics. Stegomyia house index (HI) of less than 1% indicates no risk of a dengue outbreak in Brazil [ 128 ] but outbreaks occurred in Singapore when the national overall HI was less than 1% [ 129 ]. Researchers have shown that the geographical level heterogeneity affects the performance of thresholds with the thresholds developed for smaller units performing best [ 120 ]. The thresholds varied among different spatial units such as different districts in the same country [ 37 , 41 ] as well as among different climatic zones in the same country [ 39 ]. Romiti et al. [ 130 ] report a significant difference in Ae . albopictus development threshold temperature among municipalities. In contrast, some studies report the same threshold for the seasonal emergence of Ae . albopictus in two countries [ 18 , 47 ]. Bowman et al. [ 124 ] report the predictive ability of certain meteorological and epidemiological alarm variables of dengue across all countries studied. Hence, there could not be universally reliable thresholds and there is no definitive fact that the same threshold cannot be used elsewhere. The majority of the publications analyzed here have action thresholds intended to be used in the same spatial unit as its origin. However, locations with similar determinant characteristics but yet unable to collect required surveillance data would need to consider using an already developed appropriate threshold after confirming with initial environmental assessments/validations.

Temporal resolution of data collection and analysis plays an important role in the development of reliable action thresholds. Smaller scale resolutions (e.g. weekly data) would reveal more precise relationships between variables compared to higher scale resolutions (e.g. monthly/yearly data) [ 131 ]. Realistically, the available resources and other logistics will be deterministic factors of the temporal resolution of data collection. However, most of the studies included in this review achieved at least a monthly resolution.

One of the main purposes of establishing mosquito control action thresholds is to provide sufficient time for planning, organizing, and implementing appropriate control activities at the optimal time. Sufficient lead time from the established threshold to the exceedance of its indication would help mosquito control program managers to plan, organize and implement appropriate control measures for effective reduction of mosquito populations. Entomological thresholds seem to have shorter lead time (mentioned in only 2 studies) than epidemiological thresholds. Epidemiological thresholds which used climatic variables have longer lead times than those using mosquito data variables. Hii et al. [ 132 ] discuss the importance of the optimal lead time which would give sufficient time for successful implementation of mosquito control. They suggest that an average of 2 months with maximum 3 months lead time is typically required for effective mitigation of dengue transmission in Singapore in both non-epidemic and epidemic years. The development of a reliable mosquito control action threshold/s is a very complex process due to the interplay of several tangential factors, such as frequency and amount of virus importation, and herd immunity [ 133 ] and human-mosquito contact rates [ 134 ]. However, those thresholds should be accurate enough not to provide too many false warnings which would lead to issues such as wastage of resources and development of insecticide resistance. Validation of generated thresholds is important before establishing to confirm their performance in operational settings. Validation studies have confirmed the effectiveness of thresholds generated in the same study [ 36 ] as well as previous thresholds [ 49 ]. After field validation of previous thresholds by Sanchez et al. [ 120 ], the performance of overall neighborhood Breteau Index (BI) ≥ 1.3 was denied and the most straight forward performance of BI max ≥ 4 was confirmed as an indicator for predicting dengue transmission [ 48 ]. MacCormack-Gelles et al. [ 51 ] showed that the HI threshold imposed by the Brazilian Ministry of Health was not in compliance with increasing dengue risk in Fortaleza, Brazil. Most of the thresholds included in this review still need to be field validated, before establishing to inform the need of initiation of mosquito control activities.

Limitations

Pertaining to the restrictions of available time and resources, the systematic review has several limitations which might have eliminated some important publications: (i) the literature search was limited only to two search engines (Google scholar and PubMed), (ii) the search was limited to 2010–2021, (iii) language restricted to English only, and (iv) grey literature not used.

Conclusions

Supporting information

S1 checklist. prisma checklist for abstracts..

https://doi.org/10.1371/journal.pntd.0011173.s001

S2 Checklist. PRISMA checklist.

https://doi.org/10.1371/journal.pntd.0011173.s002

S1 Table. Generated mosquito control action thresholds (“generated thresholds”) found in publications included in the review.

https://doi.org/10.1371/journal.pntd.0011173.s003

S2 Table. Generated models for mosquito control action thresholds (“generated-models”) found in publications included in the review.

https://doi.org/10.1371/journal.pntd.0011173.s004

S3 Table. Mentioned mosquito control action thresholds (“mentioned thresholds”) found in publications included in the review.

https://doi.org/10.1371/journal.pntd.0011173.s005

Acknowledgments

The authors acknowledge all the support by Anastasia Mosquito Control District, St. Augustine, Florida.

The Financial Express

A treasure trove, in verse and prose | Book Review – The Book of Bihari Literature by Abhay K

In an attempt to trace the journey of his state’s literary legacy, the author goes on his own, bringing to the fore the best of known and not-so-known poets and storytellers..

By Amitabh Ranjan

Free, fabulously free… free from three trifles… pounder, pounding bowl and my wicked lord… free from endless births and deaths… the chains that fettered me down are suddenly no more

Penned in the 6th century BCE by Mutta, a Buddhist nun, it is the first poem in The Book of Bihari Literature edited by Abhay K. The contemporaneousness of the theme is a refreshing surprise when you realise the antiquity of the composition.

Here's how many Crores Nithin Kamath and his wife Seema Patil take home as their salary

Literature does not merely chronicle a people’s history and culture. The ink that recounts a tale, one of evolution, emancipation, beauty, ugliness, courage, frailty or passion, also breathes life into characters and their surroundings. The word picture thus created brings you up close and personal with your bygone, or the present.

That’s exactly what the book achieves. An anthology of English translation of poems and short stories written over centuries, it mirrors the aspiration of the Bihari society, its contradictions, its reformist zeal, its perseverance in coming to terms with the changing times down the ages. By selecting works from a range of languages—from the ancient Pali, Prakrit and Sanskrit to Hindi, Maithili, Bhojpuri, Magahi and lesser known Bajjika and Angika—the book has managed to capture between its covers a kind of literary legacy that is not commonly found.

In the range of themes, too, Abhay K has been impressive. So, while Mutta writes about women’s emancipation, Vidyapati sings an ode to the woman’s body in his inimitable style. While Kautilya offers you some worldly wisdom, Vatsyayana guides you in the art of love-making. While an excerpt from Ramdhari Singh Dinkar’s ‘mahakavya’ Rashmirathi leaves you wanting for more, his short story Through the Prism of Time makes you aware about a changing social equation.

Jankavi Nagarjun’s poem Famine and After comprises just eight lines. Written during a phase in his life when his theme shifted from lyrical romanticism to rebellion, it’s about famine, hunger, anguish and government apathy. The translation of Chalni ke Chalal Dulha, a poem composed by Bhikhari Thakur, who earned the sobriquet Shakespeare of Bhojpuri, is about how a bridegroom is welcomed when he reaches the bride’s home.

Also read: Bernard Arnault to Elon Musk: Educational qualifications of the richest people in the world

Fish by Rajkamal Chaudhary comes with the message that love has the power to bridge cultural chasm. Mithilesh’s Chilled to the Bone is a heart-rending account of an old destitute couple in mortal combat with biting cold on a winter night. The following morning only one wakes up.

The book ends with the editor’s twin Nalanda Poems—one of despair arising out of the loss of a priceless heritage, the other of hope and determination of rising from the ashes phoenix-like.

These are just a glimpse of a very rich fare that awaits you in case you decide to partake of this delectable potpourri.

Also read: How technology can augment the Union Budget’s Green Growth Goals

It is well-neigh impossible to capture within a span of 350-odd pages the literary accomplishments of a land as ancient and as diverse as that of Bihar . Some may miss names like Gopal Singh Nepali (Hindi), Harimohan Jha and Upendranath Jha (Maithili) and Dharikshan Mishra (Bhojpuri) among others. The book nevertheless has done a commendable job of bringing together the works of authors and poets, many of whom remain unknown and, therefore, unsung. It has also shown light on quite a few figures from Bihar who can claim a seat in the country’s literary pantheon with equal ease. An addition to this volume would be an idea worth undertaking.

If you are literary inclined and a proud Bihari, this is a kaleidoscope you can’t afford to miss.

The Book of Bihari Literature

HarperCollins

Pp 408, Rs 699

A former journalist, Amitabh Ranjan teaches at Patna Women’s College

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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).
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A literature review is a comprehensive summary of previous research on a topic. The literature review surveys scholarly articles, books, and other sources relevant to a particular area of research. The review should enumerate, describe, summarize, objectively evaluate and clarify this previous research.
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A literature review is much more than an annotated bibliography or a list of separate reviews of articles and books. It is a critical, analytical summary and synthesis of the current knowledge of a topic. Thus it should compare and relate different theories, findings, etc, rather than just summarize them individually.
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Literature Review is a comprehensive survey of the works published in a particular field of study or line of research, usually over a specific period of time, in the form of an in-depth, critical bibliographic essay or annotated list in which attention is drawn to the most significant works.
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A literature review discusses published information in a particular subject area, and sometimes information in a particular subject area within a certain time period. A literature review can be just a simple summary of the sources, but it usually has an organizational pattern and combines both summary and synthesis.
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A Literature Review surveys scholarly source materials that are relevant to a person's research thesis/problem and/or a particular issue or theory. It also provides a critical analysis that summarizes and synthesizes the source materials while also demonstrating how a person's research pertains to or fits within the larger discipline of study.
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What is a literature review? The word "literature review" can refer to two related things that are part of the broader literature review process. The first is the task of reviewing the literature - i.e. sourcing and reading through the existing research relating to your research topic.
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Literature reviews are a form of academic writing commonly used in the sciences, social sciences, and humanities. However, unlike research papers, which establish new arguments and make original contributions, literature reviews organize and present existing research.
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A literature or narrative review is a comprehensive review and analysis of the published literature on a specific topic or research question. The literature that is reviewed contains: books, articles, academic articles, conference proceedings, association papers, and dissertations.
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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
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A literature review is more than a summary of the sources, it has an organizational pattern that combines both summary and synthesis. A summary is a recap of the important information of the source, but a synthesis is a re-organization, or a reshuffling, of that information. It might give a new interpretation of old material or combine new with ...
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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.
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According to the definition, a literature review is a body of work that explores various publications within a specific subject area and sometimes within a set timeframe. This type of writing requires you to read and analyze various sources that relate to the main subject and present each unique comprehension of the publications.
Systematic Review
A literature review is a survey of scholarly sources (such as books, journal articles, and theses) related to a specific topic or research question. It is often written as part of a thesis, dissertation, or research paper, in order to situate your work in relation to existing knowledge.
[Solved] A literature review is an account of what has been published
A literature review is an account of what has been published on a topic (in journal articles, conference proceedings, books and other relevant sources) by recognised researchers. Understanding the prior research on the topic of interest is the basis of most new research. Researchers must know what has been studied, found, discussed and ...
Leadership Development: Definition and Literature Review
Leadership development literature. Most of the Leadership writing up until recently was dominated by style theories of leadership. However, given the new challenges organizations have to deal with in a time of such uncertainty and interdependency where rapid changes in the technology and economy areas are seen, can make such models quite incomplete (Clarke, 2012).
Literature review
A literature review is an overview of the previously published works on a topic. The term can refer to a full scholarly paper or a section of a scholarly work such as a book, or an article. Either way, a literature review is supposed to provide the researcher/author and the audiences with a general image of the existing knowledge on the topic ...
The goal of the literature review is to review what others have
The goal of the literature review is to review what others have said about the problem, issue, concern, or need you identified and promising solutions. How will you search for appropriate scholarly literature? Share strategies you will use to assure your literature review is connected to your action research.
5. The Literature Review
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. Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper. Fourth edition. Thousand Oaks, CA: SAGE, 2014.
What is a Literature Review?
A literature review is a critical and in depth evaluation of previous research. It is a summary and synopsis of a particular area of research, allowing anybody reading the paper to establish why you are pursuing this particular research. A good literature review expands on the reasons behind selecting a particular research question.
How To Structure A Literature Review (Free Template)
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.
A systematic review of published literature on mosquito control action
The review uncovers (i) the gap in the literature on action thresholds for mosquito nuisance, other mosquito-borne- diseases than dengue in Asia, mosquito-borne diseases in other geographic regions and (ii) the need to update previous action thresholds in space and time.
A treasure trove, in verse and prose
Literature does not merely chronicle a people's history and culture. The ink that recounts a tale, one of evolution, emancipation, beauty, ugliness, courage, frailty or passion, also breathes ...