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APA Abstract (2020) | Formatting, Length, and Keywords
Published on November 6, 2020 by Raimo Streefkerk . Revised on January 17, 2024.
An APA abstract is a comprehensive summary of your paper in which you briefly address the research problem , hypotheses , methods , results , and implications of your research. It’s placed on a separate page right after the title page and is usually no longer than 250 words.
Most professional papers that are submitted for publication require an abstract. Student papers typically don’t need an abstract, unless instructed otherwise.
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Table of contents
How to format the abstract, how to write an apa abstract, which keywords to use, frequently asked questions, apa abstract example.
Follow these five steps to format your abstract in APA Style:
- Insert a running head (for a professional paper—not needed for a student paper) and page number.
- Set page margins to 1 inch (2.54 cm).
- Write “Abstract” (bold and centered) at the top of the page.
- Do not indent the first line.
- Double-space the text.
- Use a legible font like Times New Roman (12 pt.).
- Limit the length to 250 words.
- Indent the first line 0.5 inches.
- Write the label “Keywords:” (italicized).
- Write keywords in lowercase letters.
- Separate keywords with commas.
- Do not use a period after the keywords.
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The abstract is a self-contained piece of text that informs the reader what your research is about. It’s best to write the abstract after you’re finished with the rest of your paper.
The questions below may help structure your abstract. Try answering them in one to three sentences each.
- What is the problem? Outline the objective, research questions , and/or hypotheses .
- What has been done? Explain your research methods .
- What did you discover? Summarize the key findings and conclusions .
- What do the findings mean? Summarize the discussion and recommendations .
Check out our guide on how to write an abstract for more guidance and an annotated example.
Guide: writing an abstract
At the end of the abstract, you may include a few keywords that will be used for indexing if your paper is published on a database. Listing your keywords will help other researchers find your work.
Choosing relevant keywords is essential. Try to identify keywords that address your topic, method, or population. APA recommends including three to five keywords.
An abstract is a concise summary of an academic text (such as a journal article or dissertation ). It serves two main purposes:
- To help potential readers determine the relevance of your paper for their own research.
- To communicate your key findings to those who don’t have time to read the whole paper.
Abstracts are often indexed along with keywords on academic databases, so they make your work more easily findable. Since the abstract is the first thing any reader sees, it’s important that it clearly and accurately summarizes the contents of your paper.
An APA abstract is around 150–250 words long. However, always check your target journal’s guidelines and don’t exceed the specified word count.
In an APA Style paper , the abstract is placed on a separate page after the title page (page 2).
Avoid citing sources in your abstract . There are two reasons for this:
- The abstract should focus on your original research, not on the work of others.
- The abstract should be self-contained and fully understandable without reference to other sources.
There are some circumstances where you might need to mention other sources in an abstract: for example, if your research responds directly to another study or focuses on the work of a single theorist. In general, though, don’t include citations unless absolutely necessary.
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Streefkerk, R. (2024, January 17). APA Abstract (2020) | Formatting, Length, and Keywords. Scribbr. Retrieved February 22, 2024, from https://www.scribbr.com/apa-style/apa-abstract/
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How do I Write a Literature Review?: #5 Writing the Review
- Step #1: Choosing a Topic
- Step #2: Finding Information
- Step #3: Evaluating Content
- Step #4: Synthesizing Content
- #5 Writing the Review
- Citing Your Sources
WRITING THE REVIEW
You've done the research and now you're ready to put your findings down on paper. When preparing to write your review, first consider how will you organize your review.
The actual review generally has 5 components:
Abstract - An abstract is a summary of your literature review. It is made up of the following parts:
- A contextual sentence about your motivation behind your research topic
- Your thesis statement
- A descriptive statement about the types of literature used in the review
- Summarize your findings
- Conclusion(s) based upon your findings
Introduction : Like a typical research paper introduction, provide the reader with a quick idea of the topic of the literature review:
- Define or identify the general topic, issue, or area of concern. This provides the reader with context for reviewing the literature.
- Identify related trends in what has already been published about the topic; or conflicts in theory, methodology, evidence, and conclusions; or gaps in research and scholarship; or a single problem or new perspective of immediate interest.
- Establish your reason (point of view) for reviewing the literature; explain the criteria to be used in analyzing and comparing literature and the organization of the review (sequence); and, when necessary, state why certain literature is or is not included (scope) -
Body : The body of a literature review contains your discussion of sources and can be organized in 3 ways-
- Chronological - by publication or by trend
- Thematic - organized around a topic or issue, rather than the progression of time
- Methodical - the focusing factor usually does not have to do with the content of the material. Instead, it focuses on the "methods" of the literature's researcher or writer that you are reviewing
You may also want to include a section on "questions for further research" and discuss what questions the review has sparked about the topic/field or offer suggestions for future studies/examinations that build on your current findings.
Conclusion : In the conclusion, you should:
Conclude your paper by providing your reader with some perspective on the relationship between your literature review's specific topic and how it's related to it's parent discipline, scientific endeavor, or profession.
Bibliography : Since a literature review is composed of pieces of research, it is very important that your correctly cite the literature you are reviewing, both in the reviews body as well as in a bibliography/works cited. To learn more about different citation styles, visit the " Citing Your Sources " tab.
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What this handout is about
This handout provides definitions and examples of the two main types of abstracts: descriptive and informative. It also provides guidelines for constructing an abstract and general tips for you to keep in mind when drafting. Finally, it includes a few examples of abstracts broken down into their component parts.
What is an abstract?
An abstract is a self-contained, short, and powerful statement that describes a larger work. Components vary according to discipline. An abstract of a social science or scientific work may contain the scope, purpose, results, and contents of the work. An abstract of a humanities work may contain the thesis, background, and conclusion of the larger work. An abstract is not a review, nor does it evaluate the work being abstracted. While it contains key words found in the larger work, the abstract is an original document rather than an excerpted passage.
Why write an abstract?
You may write an abstract for various reasons. The two most important are selection and indexing. Abstracts allow readers who may be interested in a longer work to quickly decide whether it is worth their time to read it. Also, many online databases use abstracts to index larger works. Therefore, abstracts should contain keywords and phrases that allow for easy searching.
Say you are beginning a research project on how Brazilian newspapers helped Brazil’s ultra-liberal president Luiz Ignácio da Silva wrest power from the traditional, conservative power base. A good first place to start your research is to search Dissertation Abstracts International for all dissertations that deal with the interaction between newspapers and politics. “Newspapers and politics” returned 569 hits. A more selective search of “newspapers and Brazil” returned 22 hits. That is still a fair number of dissertations. Titles can sometimes help winnow the field, but many titles are not very descriptive. For example, one dissertation is titled “Rhetoric and Riot in Rio de Janeiro.” It is unclear from the title what this dissertation has to do with newspapers in Brazil. One option would be to download or order the entire dissertation on the chance that it might speak specifically to the topic. A better option is to read the abstract. In this case, the abstract reveals the main focus of the dissertation:
This dissertation examines the role of newspaper editors in the political turmoil and strife that characterized late First Empire Rio de Janeiro (1827-1831). Newspaper editors and their journals helped change the political culture of late First Empire Rio de Janeiro by involving the people in the discussion of state. This change in political culture is apparent in Emperor Pedro I’s gradual loss of control over the mechanisms of power. As the newspapers became more numerous and powerful, the Emperor lost his legitimacy in the eyes of the people. To explore the role of the newspapers in the political events of the late First Empire, this dissertation analyzes all available newspapers published in Rio de Janeiro from 1827 to 1831. Newspapers and their editors were leading forces in the effort to remove power from the hands of the ruling elite and place it under the control of the people. In the process, newspapers helped change how politics operated in the constitutional monarchy of Brazil.
From this abstract you now know that although the dissertation has nothing to do with modern Brazilian politics, it does cover the role of newspapers in changing traditional mechanisms of power. After reading the abstract, you can make an informed judgment about whether the dissertation would be worthwhile to read.
Besides selection, the other main purpose of the abstract is for indexing. Most article databases in the online catalog of the library enable you to search abstracts. This allows for quick retrieval by users and limits the extraneous items recalled by a “full-text” search. However, for an abstract to be useful in an online retrieval system, it must incorporate the key terms that a potential researcher would use to search. For example, if you search Dissertation Abstracts International using the keywords “France” “revolution” and “politics,” the search engine would search through all the abstracts in the database that included those three words. Without an abstract, the search engine would be forced to search titles, which, as we have seen, may not be fruitful, or else search the full text. It’s likely that a lot more than 60 dissertations have been written with those three words somewhere in the body of the entire work. By incorporating keywords into the abstract, the author emphasizes the central topics of the work and gives prospective readers enough information to make an informed judgment about the applicability of the work.
When do people write abstracts?
- when submitting articles to journals, especially online journals
- when applying for research grants
- when writing a book proposal
- when completing the Ph.D. dissertation or M.A. thesis
- when writing a proposal for a conference paper
- when writing a proposal for a book chapter
Most often, the author of the entire work (or prospective work) writes the abstract. However, there are professional abstracting services that hire writers to draft abstracts of other people’s work. In a work with multiple authors, the first author usually writes the abstract. Undergraduates are sometimes asked to draft abstracts of books/articles for classmates who have not read the larger work.
Types of abstracts
There are two types of abstracts: descriptive and informative. They have different aims, so as a consequence they have different components and styles. There is also a third type called critical, but it is rarely used. If you want to find out more about writing a critique or a review of a work, see the UNC Writing Center handout on writing a literature review . If you are unsure which type of abstract you should write, ask your instructor (if the abstract is for a class) or read other abstracts in your field or in the journal where you are submitting your article.
A descriptive abstract indicates the type of information found in the work. It makes no judgments about the work, nor does it provide results or conclusions of the research. It does incorporate key words found in the text and may include the purpose, methods, and scope of the research. Essentially, the descriptive abstract describes the work being abstracted. Some people consider it an outline of the work, rather than a summary. Descriptive abstracts are usually very short—100 words or less.
The majority of abstracts are informative. While they still do not critique or evaluate a work, they do more than describe it. A good informative abstract acts as a surrogate for the work itself. That is, the writer presents and explains all the main arguments and the important results and evidence in the complete article/paper/book. An informative abstract includes the information that can be found in a descriptive abstract (purpose, methods, scope) but also includes the results and conclusions of the research and the recommendations of the author. The length varies according to discipline, but an informative abstract is rarely more than 10% of the length of the entire work. In the case of a longer work, it may be much less.
Here are examples of a descriptive and an informative abstract of this handout on abstracts . Descriptive abstract:
The two most common abstract types—descriptive and informative—are described and examples of each are provided.
Abstracts present the essential elements of a longer work in a short and powerful statement. The purpose of an abstract is to provide prospective readers the opportunity to judge the relevance of the longer work to their projects. Abstracts also include the key terms found in the longer work and the purpose and methods of the research. Authors abstract various longer works, including book proposals, dissertations, and online journal articles. There are two main types of abstracts: descriptive and informative. A descriptive abstract briefly describes the longer work, while an informative abstract presents all the main arguments and important results. This handout provides examples of various types of abstracts and instructions on how to construct one.
Which type should I use?
Your best bet in this case is to ask your instructor or refer to the instructions provided by the publisher. You can also make a guess based on the length allowed; i.e., 100-120 words = descriptive; 250+ words = informative.
How do I write an abstract?
The format of your abstract will depend on the work being abstracted. An abstract of a scientific research paper will contain elements not found in an abstract of a literature article, and vice versa. However, all abstracts share several mandatory components, and there are also some optional parts that you can decide to include or not. When preparing to draft your abstract, keep the following key process elements in mind:
- Reason for writing: What is the importance of the research? Why would a reader be interested in the larger work?
- Problem: What problem does this work attempt to solve? What is the scope of the project? What is the main argument/thesis/claim?
- Methodology: An abstract of a scientific work may include specific models or approaches used in the larger study. Other abstracts may describe the types of evidence used in the research.
- Results: Again, an abstract of a scientific work may include specific data that indicates the results of the project. Other abstracts may discuss the findings in a more general way.
- Implications: What changes should be implemented as a result of the findings of the work? How does this work add to the body of knowledge on the topic?
(This list of elements is adapted with permission from Philip Koopman, “How to Write an Abstract.” )
All abstracts include:
- A full citation of the source, preceding the abstract.
- The most important information first.
- The same type and style of language found in the original, including technical language.
- Key words and phrases that quickly identify the content and focus of the work.
- Clear, concise, and powerful language.
Abstracts may include:
- The thesis of the work, usually in the first sentence.
- Background information that places the work in the larger body of literature.
- The same chronological structure as the original work.
How not to write an abstract:
- Do not refer extensively to other works.
- Do not add information not contained in the original work.
- Do not define terms.
If you are abstracting your own writing
When abstracting your own work, it may be difficult to condense a piece of writing that you have agonized over for weeks (or months, or even years) into a 250-word statement. There are some tricks that you could use to make it easier, however.
This technique is commonly used when you are having trouble organizing your own writing. The process involves writing down the main idea of each paragraph on a separate piece of paper– see our short video . For the purposes of writing an abstract, try grouping the main ideas of each section of the paper into a single sentence. Practice grouping ideas using webbing or color coding .
For a scientific paper, you may have sections titled Purpose, Methods, Results, and Discussion. Each one of these sections will be longer than one paragraph, but each is grouped around a central idea. Use reverse outlining to discover the central idea in each section and then distill these ideas into one statement.
Cut and paste:
To create a first draft of an abstract of your own work, you can read through the entire paper and cut and paste sentences that capture key passages. This technique is useful for social science research with findings that cannot be encapsulated by neat numbers or concrete results. A well-written humanities draft will have a clear and direct thesis statement and informative topic sentences for paragraphs or sections. Isolate these sentences in a separate document and work on revising them into a unified paragraph.
If you are abstracting someone else’s writing
When abstracting something you have not written, you cannot summarize key ideas just by cutting and pasting. Instead, you must determine what a prospective reader would want to know about the work. There are a few techniques that will help you in this process:
Identify key terms:
Search through the entire document for key terms that identify the purpose, scope, and methods of the work. Pay close attention to the Introduction (or Purpose) and the Conclusion (or Discussion). These sections should contain all the main ideas and key terms in the paper. When writing the abstract, be sure to incorporate the key terms.
Highlight key phrases and sentences:
Instead of cutting and pasting the actual words, try highlighting sentences or phrases that appear to be central to the work. Then, in a separate document, rewrite the sentences and phrases in your own words.
Don’t look back:
After reading the entire work, put it aside and write a paragraph about the work without referring to it. In the first draft, you may not remember all the key terms or the results, but you will remember what the main point of the work was. Remember not to include any information you did not get from the work being abstracted.
Revise, revise, revise
No matter what type of abstract you are writing, or whether you are abstracting your own work or someone else’s, the most important step in writing an abstract is to revise early and often. When revising, delete all extraneous words and incorporate meaningful and powerful words. The idea is to be as clear and complete as possible in the shortest possible amount of space. The Word Count feature of Microsoft Word can help you keep track of how long your abstract is and help you hit your target length.
Example 1: Humanities abstract
Kenneth Tait Andrews, “‘Freedom is a constant struggle’: The dynamics and consequences of the Mississippi Civil Rights Movement, 1960-1984” Ph.D. State University of New York at Stony Brook, 1997 DAI-A 59/02, p. 620, Aug 1998
This dissertation examines the impacts of social movements through a multi-layered study of the Mississippi Civil Rights Movement from its peak in the early 1960s through the early 1980s. By examining this historically important case, I clarify the process by which movements transform social structures and the constraints movements face when they try to do so. The time period studied includes the expansion of voting rights and gains in black political power, the desegregation of public schools and the emergence of white-flight academies, and the rise and fall of federal anti-poverty programs. I use two major research strategies: (1) a quantitative analysis of county-level data and (2) three case studies. Data have been collected from archives, interviews, newspapers, and published reports. This dissertation challenges the argument that movements are inconsequential. Some view federal agencies, courts, political parties, or economic elites as the agents driving institutional change, but typically these groups acted in response to the leverage brought to bear by the civil rights movement. The Mississippi movement attempted to forge independent structures for sustaining challenges to local inequities and injustices. By propelling change in an array of local institutions, movement infrastructures had an enduring legacy in Mississippi.
Now let’s break down this abstract into its component parts to see how the author has distilled his entire dissertation into a ~200 word abstract.
What the dissertation does This dissertation examines the impacts of social movements through a multi-layered study of the Mississippi Civil Rights Movement from its peak in the early 1960s through the early 1980s. By examining this historically important case, I clarify the process by which movements transform social structures and the constraints movements face when they try to do so.
How the dissertation does it The time period studied in this dissertation includes the expansion of voting rights and gains in black political power, the desegregation of public schools and the emergence of white-flight academies, and the rise and fall of federal anti-poverty programs. I use two major research strategies: (1) a quantitative analysis of county-level data and (2) three case studies.
What materials are used Data have been collected from archives, interviews, newspapers, and published reports.
Conclusion This dissertation challenges the argument that movements are inconsequential. Some view federal agencies, courts, political parties, or economic elites as the agents driving institutional change, but typically these groups acted in response to movement demands and the leverage brought to bear by the civil rights movement. The Mississippi movement attempted to forge independent structures for sustaining challenges to local inequities and injustices. By propelling change in an array of local institutions, movement infrastructures had an enduring legacy in Mississippi.
Keywords social movements Civil Rights Movement Mississippi voting rights desegregation
Example 2: Science Abstract
Luis Lehner, “Gravitational radiation from black hole spacetimes” Ph.D. University of Pittsburgh, 1998 DAI-B 59/06, p. 2797, Dec 1998
The problem of detecting gravitational radiation is receiving considerable attention with the construction of new detectors in the United States, Europe, and Japan. The theoretical modeling of the wave forms that would be produced in particular systems will expedite the search for and analysis of detected signals. The characteristic formulation of GR is implemented to obtain an algorithm capable of evolving black holes in 3D asymptotically flat spacetimes. Using compactification techniques, future null infinity is included in the evolved region, which enables the unambiguous calculation of the radiation produced by some compact source. A module to calculate the waveforms is constructed and included in the evolution algorithm. This code is shown to be second-order convergent and to handle highly non-linear spacetimes. In particular, we have shown that the code can handle spacetimes whose radiation is equivalent to a galaxy converting its whole mass into gravitational radiation in one second. We further use the characteristic formulation to treat the region close to the singularity in black hole spacetimes. The code carefully excises a region surrounding the singularity and accurately evolves generic black hole spacetimes with apparently unlimited stability.
This science abstract covers much of the same ground as the humanities one, but it asks slightly different questions.
Why do this study The problem of detecting gravitational radiation is receiving considerable attention with the construction of new detectors in the United States, Europe, and Japan. The theoretical modeling of the wave forms that would be produced in particular systems will expedite the search and analysis of the detected signals.
What the study does The characteristic formulation of GR is implemented to obtain an algorithm capable of evolving black holes in 3D asymptotically flat spacetimes. Using compactification techniques, future null infinity is included in the evolved region, which enables the unambiguous calculation of the radiation produced by some compact source. A module to calculate the waveforms is constructed and included in the evolution algorithm.
Results This code is shown to be second-order convergent and to handle highly non-linear spacetimes. In particular, we have shown that the code can handle spacetimes whose radiation is equivalent to a galaxy converting its whole mass into gravitational radiation in one second. We further use the characteristic formulation to treat the region close to the singularity in black hole spacetimes. The code carefully excises a region surrounding the singularity and accurately evolves generic black hole spacetimes with apparently unlimited stability.
Keywords gravitational radiation (GR) spacetimes black holes
We consulted these works while writing this handout. This is not a comprehensive list of resources on the handout’s topic, and we encourage you to do your own research to find additional publications. Please do not use this list as a model for the format of your own reference list, as it may not match the citation style you are using. For guidance on formatting citations, please see the UNC Libraries citation tutorial . We revise these tips periodically and welcome feedback.
Belcher, Wendy Laura. 2009. Writing Your Journal Article in Twelve Weeks: A Guide to Academic Publishing Success. Thousand Oaks, CA: Sage Press.
Koopman, Philip. 1997. “How to Write an Abstract.” Carnegie Mellon University. October 1997. http://users.ece.cmu.edu/~koopman/essays/abstract.html .
Lancaster, F.W. 2003. Indexing And Abstracting in Theory and Practice , 3rd ed. London: Facet Publishing.
You may reproduce it for non-commercial use if you use the entire handout and attribute the source: The Writing Center, University of North Carolina at Chapel Hill
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Writing a Literature Review
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A literature review is a document or section of a document that collects key sources on a topic and discusses those sources in conversation with each other (also called synthesis ). The lit review is an important genre in many disciplines, not just literature (i.e., the study of works of literature such as novels and plays). When we say “literature review” or refer to “the literature,” we are talking about the research ( scholarship ) in a given field. You will often see the terms “the research,” “the scholarship,” and “the literature” used mostly interchangeably.
Where, when, and why would I write a lit review?
There are a number of different situations where you might write a literature review, each with slightly different expectations; different disciplines, too, have field-specific expectations for what a literature review is and does. For instance, in the humanities, authors might include more overt argumentation and interpretation of source material in their literature reviews, whereas in the sciences, authors are more likely to report study designs and results in their literature reviews; these differences reflect these disciplines’ purposes and conventions in scholarship. You should always look at examples from your own discipline and talk to professors or mentors in your field to be sure you understand your discipline’s conventions, for literature reviews as well as for any other genre.
A literature review can be a part of a research paper or scholarly article, usually falling after the introduction and before the research methods sections. In these cases, the lit review just needs to cover scholarship that is important to the issue you are writing about; sometimes it will also cover key sources that informed your research methodology.
Lit reviews can also be standalone pieces, either as assignments in a class or as publications. In a class, a lit review may be assigned to help students familiarize themselves with a topic and with scholarship in their field, get an idea of the other researchers working on the topic they’re interested in, find gaps in existing research in order to propose new projects, and/or develop a theoretical framework and methodology for later research. As a publication, a lit review usually is meant to help make other scholars’ lives easier by collecting and summarizing, synthesizing, and analyzing existing research on a topic. This can be especially helpful for students or scholars getting into a new research area, or for directing an entire community of scholars toward questions that have not yet been answered.
What are the parts of a lit review?
Most lit reviews use a basic introduction-body-conclusion structure; if your lit review is part of a larger paper, the introduction and conclusion pieces may be just a few sentences while you focus most of your attention on the body. If your lit review is a standalone piece, the introduction and conclusion take up more space and give you a place to discuss your goals, research methods, and conclusions separately from where you discuss the literature itself.
- An introductory paragraph that explains what your working topic and thesis is
- A forecast of key topics or texts that will appear in the review
- Potentially, a description of how you found sources and how you analyzed them for inclusion and discussion in the review (more often found in published, standalone literature reviews than in lit review sections in an article or research paper)
- Summarize and synthesize: Give an overview of the main points of each source and combine them into a coherent whole
- Analyze and interpret: Don’t just paraphrase other researchers – add your own interpretations where possible, discussing the significance of findings in relation to the literature as a whole
- Critically Evaluate: Mention the strengths and weaknesses of your sources
- Write in well-structured paragraphs: Use transition words and topic sentence to draw connections, comparisons, and contrasts.
- Summarize the key findings you have taken from the literature and emphasize their significance
- Connect it back to your primary research question
How should I organize my lit review?
Lit reviews can take many different organizational patterns depending on what you are trying to accomplish with the review. Here are some examples:
- Chronological : The simplest approach is to trace the development of the topic over time, which helps familiarize the audience with the topic (for instance if you are introducing something that is not commonly known in your field). If you choose this strategy, be careful to avoid simply listing and summarizing sources in order. Try to analyze the patterns, turning points, and key debates that have shaped the direction of the field. Give your interpretation of how and why certain developments occurred (as mentioned previously, this may not be appropriate in your discipline — check with a teacher or mentor if you’re unsure).
- Thematic : If you have found some recurring central themes that you will continue working with throughout your piece, you can organize your literature review into subsections that address different aspects of the topic. For example, if you are reviewing literature about women and religion, key themes can include the role of women in churches and the religious attitude towards women.
- Qualitative versus quantitative research
- Empirical versus theoretical scholarship
- Divide the research by sociological, historical, or cultural sources
- Theoretical : In many humanities articles, the literature review is the foundation for the theoretical framework. You can use it to discuss various theories, models, and definitions of key concepts. You can argue for the relevance of a specific theoretical approach or combine various theorical concepts to create a framework for your research.
What are some strategies or tips I can use while writing my lit review?
Any lit review is only as good as the research it discusses; make sure your sources are well-chosen and your research is thorough. Don’t be afraid to do more research if you discover a new thread as you’re writing. More info on the research process is available in our "Conducting Research" resources .
As you’re doing your research, create an annotated bibliography ( see our page on the this type of document ). Much of the information used in an annotated bibliography can be used also in a literature review, so you’ll be not only partially drafting your lit review as you research, but also developing your sense of the larger conversation going on among scholars, professionals, and any other stakeholders in your topic.
Usually you will need to synthesize research rather than just summarizing it. This means drawing connections between sources to create a picture of the scholarly conversation on a topic over time. Many student writers struggle to synthesize because they feel they don’t have anything to add to the scholars they are citing; here are some strategies to help you:
- It often helps to remember that the point of these kinds of syntheses is to show your readers how you understand your research, to help them read the rest of your paper.
- Writing teachers often say synthesis is like hosting a dinner party: imagine all your sources are together in a room, discussing your topic. What are they saying to each other?
- Look at the in-text citations in each paragraph. Are you citing just one source for each paragraph? This usually indicates summary only. When you have multiple sources cited in a paragraph, you are more likely to be synthesizing them (not always, but often
- Read more about synthesis here.
The most interesting literature reviews are often written as arguments (again, as mentioned at the beginning of the page, this is discipline-specific and doesn’t work for all situations). Often, the literature review is where you can establish your research as filling a particular gap or as relevant in a particular way. You have some chance to do this in your introduction in an article, but the literature review section gives a more extended opportunity to establish the conversation in the way you would like your readers to see it. You can choose the intellectual lineage you would like to be part of and whose definitions matter most to your thinking (mostly humanities-specific, but this goes for sciences as well). In addressing these points, you argue for your place in the conversation, which tends to make the lit review more compelling than a simple reporting of other sources.
Writing an Abstract for Your Research Paper
Definition and Purpose of Abstracts
An abstract is a short summary of your (published or unpublished) research paper, usually about a paragraph (c. 6-7 sentences, 150-250 words) long. A well-written abstract serves multiple purposes:
- an abstract lets readers get the gist or essence of your paper or article quickly, in order to decide whether to read the full paper;
- an abstract prepares readers to follow the detailed information, analyses, and arguments in your full paper;
- and, later, an abstract helps readers remember key points from your paper.
It’s also worth remembering that search engines and bibliographic databases use abstracts, as well as the title, to identify key terms for indexing your published paper. So what you include in your abstract and in your title are crucial for helping other researchers find your paper or article.
If you are writing an abstract for a course paper, your professor may give you specific guidelines for what to include and how to organize your abstract. Similarly, academic journals often have specific requirements for abstracts. So in addition to following the advice on this page, you should be sure to look for and follow any guidelines from the course or journal you’re writing for.
The Contents of an Abstract
Abstracts contain most of the following kinds of information in brief form. The body of your paper will, of course, develop and explain these ideas much more fully. As you will see in the samples below, the proportion of your abstract that you devote to each kind of information—and the sequence of that information—will vary, depending on the nature and genre of the paper that you are summarizing in your abstract. And in some cases, some of this information is implied, rather than stated explicitly. The Publication Manual of the American Psychological Association , which is widely used in the social sciences, gives specific guidelines for what to include in the abstract for different kinds of papers—for empirical studies, literature reviews or meta-analyses, theoretical papers, methodological papers, and case studies.
Here are the typical kinds of information found in most abstracts:
- the context or background information for your research; the general topic under study; the specific topic of your research
- the central questions or statement of the problem your research addresses
- what’s already known about this question, what previous research has done or shown
- the main reason(s) , the exigency, the rationale , the goals for your research—Why is it important to address these questions? Are you, for example, examining a new topic? Why is that topic worth examining? Are you filling a gap in previous research? Applying new methods to take a fresh look at existing ideas or data? Resolving a dispute within the literature in your field? . . .
- your research and/or analytical methods
- your main findings , results , or arguments
- the significance or implications of your findings or arguments.
Your abstract should be intelligible on its own, without a reader’s having to read your entire paper. And in an abstract, you usually do not cite references—most of your abstract will describe what you have studied in your research and what you have found and what you argue in your paper. In the body of your paper, you will cite the specific literature that informs your research.
When to Write Your Abstract
Although you might be tempted to write your abstract first because it will appear as the very first part of your paper, it’s a good idea to wait to write your abstract until after you’ve drafted your full paper, so that you know what you’re summarizing.
What follows are some sample abstracts in published papers or articles, all written by faculty at UW-Madison who come from a variety of disciplines. We have annotated these samples to help you see the work that these authors are doing within their abstracts.
Choosing Verb Tenses within Your Abstract
The social science sample (Sample 1) below uses the present tense to describe general facts and interpretations that have been and are currently true, including the prevailing explanation for the social phenomenon under study. That abstract also uses the present tense to describe the methods, the findings, the arguments, and the implications of the findings from their new research study. The authors use the past tense to describe previous research.
The humanities sample (Sample 2) below uses the past tense to describe completed events in the past (the texts created in the pulp fiction industry in the 1970s and 80s) and uses the present tense to describe what is happening in those texts, to explain the significance or meaning of those texts, and to describe the arguments presented in the article.
The science samples (Samples 3 and 4) below use the past tense to describe what previous research studies have done and the research the authors have conducted, the methods they have followed, and what they have found. In their rationale or justification for their research (what remains to be done), they use the present tense. They also use the present tense to introduce their study (in Sample 3, “Here we report . . .”) and to explain the significance of their study (In Sample 3, This reprogramming . . . “provides a scalable cell source for. . .”).
Sample Abstract 1
From the social sciences.
Reporting new findings about the reasons for increasing economic homogamy among spouses
Gonalons-Pons, Pilar, and Christine R. Schwartz. “Trends in Economic Homogamy: Changes in Assortative Mating or the Division of Labor in Marriage?” Demography , vol. 54, no. 3, 2017, pp. 985-1005.
Sample Abstract 2
From the humanities.
Analyzing underground pulp fiction publications in Tanzania, this article makes an argument about the cultural significance of those publications
Emily Callaci. “Street Textuality: Socialism, Masculinity, and Urban Belonging in Tanzania’s Pulp Fiction Publishing Industry, 1975-1985.” Comparative Studies in Society and History , vol. 59, no. 1, 2017, pp. 183-210.
Sample Abstract/Summary 3
From the sciences.
Reporting a new method for reprogramming adult mouse fibroblasts into induced cardiac progenitor cells
Lalit, Pratik A., Max R. Salick, Daryl O. Nelson, Jayne M. Squirrell, Christina M. Shafer, Neel G. Patel, Imaan Saeed, Eric G. Schmuck, Yogananda S. Markandeya, Rachel Wong, Martin R. Lea, Kevin W. Eliceiri, Timothy A. Hacker, Wendy C. Crone, Michael Kyba, Daniel J. Garry, Ron Stewart, James A. Thomson, Karen M. Downs, Gary E. Lyons, and Timothy J. Kamp. “Lineage Reprogramming of Fibroblasts into Proliferative Induced Cardiac Progenitor Cells by Defined Factors.” Cell Stem Cell , vol. 18, 2016, pp. 354-367.
Sample Abstract 4, a Structured Abstract
Reporting results about the effectiveness of antibiotic therapy in managing acute bacterial sinusitis, from a rigorously controlled study
Note: This journal requires authors to organize their abstract into four specific sections, with strict word limits. Because the headings for this structured abstract are self-explanatory, we have chosen not to add annotations to this sample abstract.
Wald, Ellen R., David Nash, and Jens Eickhoff. “Effectiveness of Amoxicillin/Clavulanate Potassium in the Treatment of Acute Bacterial Sinusitis in Children.” Pediatrics , vol. 124, no. 1, 2009, pp. 9-15.
“OBJECTIVE: The role of antibiotic therapy in managing acute bacterial sinusitis (ABS) in children is controversial. The purpose of this study was to determine the effectiveness of high-dose amoxicillin/potassium clavulanate in the treatment of children diagnosed with ABS.
METHODS : This was a randomized, double-blind, placebo-controlled study. Children 1 to 10 years of age with a clinical presentation compatible with ABS were eligible for participation. Patients were stratified according to age (<6 or ≥6 years) and clinical severity and randomly assigned to receive either amoxicillin (90 mg/kg) with potassium clavulanate (6.4 mg/kg) or placebo. A symptom survey was performed on days 0, 1, 2, 3, 5, 7, 10, 20, and 30. Patients were examined on day 14. Children’s conditions were rated as cured, improved, or failed according to scoring rules.
RESULTS: Two thousand one hundred thirty-five children with respiratory complaints were screened for enrollment; 139 (6.5%) had ABS. Fifty-eight patients were enrolled, and 56 were randomly assigned. The mean age was 6630 months. Fifty (89%) patients presented with persistent symptoms, and 6 (11%) presented with nonpersistent symptoms. In 24 (43%) children, the illness was classified as mild, whereas in the remaining 32 (57%) children it was severe. Of the 28 children who received the antibiotic, 14 (50%) were cured, 4 (14%) were improved, 4(14%) experienced treatment failure, and 6 (21%) withdrew. Of the 28children who received placebo, 4 (14%) were cured, 5 (18%) improved, and 19 (68%) experienced treatment failure. Children receiving the antibiotic were more likely to be cured (50% vs 14%) and less likely to have treatment failure (14% vs 68%) than children receiving the placebo.
CONCLUSIONS : ABS is a common complication of viral upper respiratory infections. Amoxicillin/potassium clavulanate results in significantly more cures and fewer failures than placebo, according to parental report of time to resolution.” (9)
Some Excellent Advice about Writing Abstracts for Basic Science Research Papers, by Professor Adriano Aguzzi from the Institute of Neuropathology at the University of Zurich:
Academic and Professional Writing
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Write Abstracts, Literature Reviews, and Annotated Bibliographies: Literature Reviews
- Abstract Guides & Examples
- Literature Reviews
- Annotated Bibliographies & Examples
- Student Research
What is a Literature Review?
According to the Writing Center at University of North Carolina at Chapel Hill , "A literature review discusses published information in a particular subject area, and sometimes information in a particular subject area within a certain time period."
Although a literature review may summarize research on a given topic, it generally synthesizes and summarizes a subject. The purpose of a literature review therefore is to present summaries and analysis of current research not contribute new ideas on the topic (making it different from a research paper).
Search for Literature Reviews
How to Write a Literature Review
- Learn How to Write a Review of Literature (The University of Wisconsin)
- The Literature Review: A Few Tips On Conducting It (University of Totonto)
- Write a Literature Review (UC Santa Cruz)
- Teaching the Literature Review Details strategies on how to teach students about literature reviews and how to create their own reviews.
Dos and Don'ts of a Literature Review
Make a clear statement of the research problem. Keep it in discussion style. Give a critical assessment of your chosen literature topic, try to state the weaknesses and gaps in previous studies, try to raise questions and give suggestions for improvement.
List your ideas or theories in an unrepeated and sensible sequence. Write a complete bibliography that provides the resources from where you had collected the data in this literature review.
Use unfamiliar technical terms or too many abbreviations. Use passive voice in your text. Repeat same ideas in your text. Include any ideas that you read in the article without citing them (author's name, publication date) as a reference source. Include punctuation and grammatical errors.
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- v.88(4); 2000 Oct
Clarifying the abstracts of systematic literature reviews *
1 Department of Psychology Keele University Staffordshire United Kingdom
2 † Author's address for correspondence: James Hartley, B.A., Ph.D., Department of Psychology, Keele University, Staffordshire, ST5 5BG, United Kingdom; email, [email protected]
Background: There is a small body of research on improving the clarity of abstracts in general that is relevant to improving the clarity of abstracts of systematic reviews.
Objectives: To summarize this earlier research and indicate its implications for writing the abstracts of systematic reviews.
Method: Literature review with commentary on three main features affecting the clarity of abstracts: their language, structure, and typographical presentation.
Conclusions: The abstracts of systematic reviews should be easier to read than the abstracts of medical research articles, as they are targeted at a wider audience. The aims, methods, results, and conclusions of systematic reviews need to be presented in a consistent way to help search and retrieval. The typographic detailing of the abstracts (type-sizes, spacing, and weights) should be planned to help, rather than confuse, the reader.
Several books and review papers have been published over the last twenty-five years about improving the clarity of the abstracts of articles in scientific journals, including several recent studies [ 1–5 ]. Three main areas of importance have been discussed:
- the language, or the readability, of an abstract;
- the sequence of information, or the structure, of an abstract; and
- the typography, or the presentation, of an abstract.
This paper considers the implications of the findings from research in each of these overlapping areas to the more specific area of writing abstracts for what are called “systematic reviews.” Such reviews in medical journals typically use standard procedures for assessing the evidence obtained from separate studies for and against the effectiveness of a particular treatment. The term “systematic” implies that the authors have used a standard approach to minimizing biases and random errors and that the methods chosen for the approach will be documented in the materials and methods sections of the review. Examples of such reviews may be found in Chalmers's and Altman's text [ 6 ] and in papers published in medical journals, particularly Evidence-Based Medicine. Figure 1 provides a fictitious example of an abstract for such a paper.
“Before” and “after” examples designed to show how differences in typography and wording can enhance the clarity of an abstract. Abstract courtesy of Philippa Middleton.
THE LANGUAGE OF THE TEXT
Research on the readability of conventional journal abstracts suggests that they are not easy to read. Studies in this area typically use the Flesch Reading Ease (R.E.) scores as their measure of text difficulty [ 7 ]. This measure, developed in the 1940s, is based upon the somewhat over simple idea that the difficulty of text is a function of the length of the sentences in the text and the length of the words within these sentences. The original Flesch formula is that R.E. = 206.835 − 0.846w − 1.015s (where w = the average number of syllables in 100 words and s = the average number of words per sentence). The scores normally range from 0 to 100, and the lower the score the more difficult the text is to read; Table 1 gives typical examples. Today, Flesch R.E. scores accompany most computerized spell checkers, and this removes the difficulties of hand calculation; although different programs give slightly different results [ 8, 9 ].
Table 1 The interpretation of Flesch scores
Table 2 summarizes the Flesch scores obtained for numerous journal abstracts in seven studies. The low scores shown here support the notion that journal abstracts are difficult to read. With medical journals, in particular, this difficulty may stem partly from complex medical terminology. Readability scores such as these are widely quoted, even though there is considerable debate about their validity, largely because they ignore the readers' prior knowledge and motivation [ 10, 11 ].
Table 2 Flesch Reading Ease scores reported in previous research on abstracts in journal articles
A second cause of difficulty in understanding text is that, although the wording may be simple and the sentences short, the concepts being described may not be understood by the reader. Thus, for example, although the sentence “God is grace” is extremely readable (in terms of the Flesch), it is not easy to explain what it actually means! In systematic reviews, to be more specific, the statistical concepts of the confidence interval and the adjusted odds ratio ( Figure 1 ) may be well understood by medical researchers, but they will not be understood by all readers.
A third cause of difficulty in prose lies in the scientific nature of the text that emphasizes the use of the third person, together with the passive rather than the active tense. Graetz writes of journal abstracts:
The abstract is characterized by the use of the past tense, the third person, passive, and the non-use of negatives…. It is written in tightly worded sentences, which avoid repetition, meaningless expressions, superlatives, adjectives, illustrations, preliminaries, descriptive details, examples, footnotes. In short it eliminates the redundancy which the skilled reader counts on finding in written language and which usually facilitates comprehension. [ 12 ]
In systematic reviews, it is easy to find sentences like “Trial eligibility and quality were assessed” that would be more readable if they were written as “We assessed the eligibility and the quality of the trials.” Furthermore, there are often short telegrammatic communications, some of which contain no verbs. Figure 1 provides an example (under the subheading “Selection criteria”).
There are, of course, numerous guidelines on how to write clear abstracts and more readable medical text [ 13–16 ] but, at present, there are few such guidelines for writing the abstracts of systematic reviews. Mulrow, Thacker, and Pugh [ 17 ] provide an excellent early example, and there are now regularly updated guidelines in the Cochrane Handbook [ 18 ].
Nonetheless, even when such guidelines are followed, evaluating the clarity of medical text is not easy. But some methods of doing so may be adapted from the more traditional literature on text evaluation. Schriver, for example, describes three different methods of text evaluation—text-based, expert-based, and reader-based methods [ 19 ]:
- Text-based methods are ones that can be used without recourse to experts or to readers. Such methods include computer-based readability formulae (such as the Flesch measure described above) and computer-based measures of style and grammar.
- Expert-based methods are ones that use experts to make assessments of the effectiveness of a piece of text. Medical experts may be asked, for example, to judge the suitability of the information contained in a patient information leaflet.
- Reader-based methods are ones that involve actual readers in making assessments of the suitability of the text, for themselves and for others. Patients, for example, may be asked to comment on medical leaflets or be tested on how much they can recall from them.
Although all three methods of evaluation are useful, especially in combination, this writer particularly recommends reader-based methods for evaluating the readability of abstracts in systematic reviews. This recommendation is because the readers of such systematic reviews are likely to be quite disparate in their aims, needs, and even in the languages that they speak. As the 1999 Cochrane Handbook put it:
Abstracts should be made as readable as possible without compromising scientific integrity. They should primarily be targeted to health care decision makers (clinicians, consumers, and policy makers) rather than just researchers. Terminology should be reasonably comprehensible to a general rather than a specialist medical audience [emphasis added]. [ 20 ]
Expert-based measures on their own may be misleading. For instance, there is evidence to suggest that the concerns of professionals are different from those of other personnel [ 21 ]. Wilson et al. [ 22 ], for instance, report wide differences between the responses of general practitioners (GPs) and patients in the United Kingdom in responses to questions concerning the content and usefulness of several patient information leaflets. Table 3 shows some of their replies.
Table 3 Differences between general practitioners (GPs) and patients in their views about particular patient information leaflets
THE STRUCTURE OF THE TEXT
In recent times, particularly in the medical field, there has been great interest in the use of so-called “structured abstracts”—abstracts that typically contain subheadings, such as “background,” “aims,” “methods,” “results,” and “conclusions.” Indeed, the early rise in the use of such abstracts was phenomenal [ 23 ], and it has no doubt continued to be so up to the present day. Evaluation studies have shown that structured abstracts are more effective than traditional ones, particularly in the sense that they contain more information [ 24–31 ]. However, a caveat here is that some authors still omit important information, and some still include information in the abstract that does not match exactly what is said in the article [ 32–35 ].
Additional research has shown that structured abstracts are sometimes easier to read and to search than are traditional ones [ 36, 37 ], but others have questioned this conclusion [ 38, 39 ]. Nonetheless, in general, both authors and readers apparently prefer structured to traditional abstracts [ 40–42 ]. The main features of structured abstracts that lead to these findings are that:
- the texts are opened-up and clearly subdivided into their component parts, which helps the reader perceive their structure;
- the abstracts sequence their information in a consistent order under consistent subheadings, which facilitates search and retrieval; and
- the writing under these subheadings ensures that authors do not miss out anything important.
Nonetheless, there are some difficulties—and these difficulties become more apparent after considering the structured abstracts of systematic reviews. First of all, the typographic practice of denoting the subheadings varies from journal to journal [ 43, 44 ]. Second, and of more relevance here, there is a range of subheadings used both within and among journals [ 45, 46 ], which militates against rapid retrieval. Table 4 shows an example of these variations by listing the subheadings used in the abstracts in just one volume of the Journal of the American Medical Association. Finally, it appears that some authors omit important subheadings or present them in a different order (e.g., reporting the conclusions before the results) [ 47 ].
Table 4 Different numbers of subheadings used in abstracts in the same volume of the Journal of the American Medical Association
The implications of these difficulties are that a decision needs to be made, based upon appropriate evaluation studies, about what are the key subheadings that can be used consistently in systematic reviews. The journal Evidence-Based Medicine, for example, uses the following six subheadings: “Question(s),” “Data sources,” “Study selection,” “Data extraction,” “Main results,” and “Conclusions,” but the Cochrane Handbook [ 48 ] recommends another seven: “Background,” “Objectives,” “Search strategy,” “Selection criteria,” “Data collection and analysis,” “Main results,” and “Reviewers' conclusions.” Presumably, these different sets of subheadings have developed over time with experience. For example, “Objective(s)” initially preceded “Question(s)” in Evidence-Based Medicine. In the future, refining these subheadings further may be possible by using appropriate typographic cueing, to separate important from minor subheadings, such as those headings used in the Journal of the American Medical Association. It will be essential, however, to use consistent terminology throughout the literature to aid both the creation of and retrieval from the abstracts of systematic reviews. Editors may consult their readers and their authors for possible solutions to this problem.
THE TYPOGRAPHIC SETTING FOR ABSTRACTS OF SYSTEMATIC REVIEWS
Early research on the typographic setting of structured abstracts in scientific articles suggests that the subheadings should be printed in bold capital letters with a line space above each subheading [ 49 ]. But this research has been done with structured abstracts that only have four subheadings. However, the abstracts of systematic reviews are likely to have more than four-subheadings—indeed, as noted above, six or seven seem typical. Also, some of these subheadings may be more important than others.
Generally speaking, there are two ways of clarifying the structure in typography. One is to vary the typography, the other to vary the spacing [ 50, 51 ]. In terms of typography, not overdoing is best; there is no need to use two cues when one will do. Thus, it may be appropriate to use bold lettering for the main subheadings and italic lettering for the less important ones, without adding the additional cues of capital letters or underlining. Also, as the subheadings appear as the first word on a line, placing a line space above them enhances their effectiveness, so there is no need to indent the subheadings as well. The abstracts published in the Cochrane Library follow this procedure.
Finally in this section, it should be noted that it is easier to read an abstract:
- that is set in the same type-size (or larger) than the body of the text of the review, unlike many journal abstracts, [ 52 ];
- that does not use “fancy'” typography or indeed bold or italic for its substantive text [ 53 ]; and
- that is set in “unjustified text,” with equal word spacing and a ragged right-hand margin, rather than in “justified text,” with unequal word spacing and straight left- and right-hand margins. This is particularly the case if the abstract is being read on screen [ 54 ].
The research reviewed above suggests that, in presenting the abstracts to systematic reviews, attention needs to be paid to their language, their structure, and their typographic design. Figure 1 shows a “before and after” example for a fictitious abstract for a systematic review. The purpose of this example is to encapsulate the argument of this paper and to show how changes in wording and typography can enhance the clarity of an abstract for a systematic review.
The author is indebted to Iain Chalmers, Philippa Middleton, Mark Starr, and anonymous referees for assistance in the preparation of this paper.
* Based on invited presentation at the VIIth Cochrane Colloquium, Rome, Italy, October 1999.
- Berkenkotter C, Huckin TN. Genre knowledge in disciplinary communication . Hillsdale, NJ: Erlbaum. 1995 [ Google Scholar ]
- Hartley J. Three ways to improve the clarity of journal abstracts . Brit J Educ Psychol . 1994 Jun. 64 ( 2 ):331–43. [ Google Scholar ]
- Swales JM. Genre analysis: English in academic and research settings . Cambridge, U.K.: Cambridge University Press. 1990 [ Google Scholar ]
- Swales JM, Feak C. Academic writing for graduate students . Michigan: University of Michigan Press. 1994 [ Google Scholar ]
- Anonymous. A proposal for more informative abstracts in clinical articles. Ad Hoc Working Group for Critical Appraisal of the Medical Literature . Ann Intern Med . 1987 Apr. 106 ( 4 ):598–604. [ PubMed ] [ Google Scholar ]
- Chalmers I, Altman DG. eds. . Systematic reviews . London, U.K.: British Medical Journal Publishing Group. 1995 [ Google Scholar ]
- Flesch R. A new readability yardstick . J Appl Psychol . 1948 Jun. 32 :221–3. [ PubMed ] [ Google Scholar ]
- Mailloux SL, Johnson ME, Fisher DG, and Pettibone TJ. How reliable is computerized assessment of readability? Computers and Nursing . 1995 Sep–Oct. 13 ( 5 ):221–5. [ PubMed ] [ Google Scholar ]
- Sydes M, Hartley J. A thorn in the Flesch: observations on the unreliability of computer-based readability formulae . British Journal of Educational Technology . 1997 Apr. 28 ( 2 ):143–5. [ Google Scholar ]
- Davison A, Green G. eds. . Linguistic complexity and text comprehension: readability issues reconsidered . Hillsdale, NJ: Erlbaum. 1988 [ Google Scholar ]
- Hartley J. Designing instructional text . 3d ed. East Brunswick, NJ: Nichols. 1994 [ Google Scholar ]
- Graetz N. Teaching EFL students to extract structural information from abstracts . In: Ulijn JM, Pugh AK, eds. Reading for professional purposes. Leuven, Belgium: ACCO. 1985 125. [ Google Scholar ]
- National Information Standards Organization. An American national standard: guidelines for abstracts . Bethesda, MD: NISO Press. 1997 [ Google Scholar ]
- Hall GM. How to write a paper . London, U.K.: BMJ Pub Group. 1994 [ Google Scholar ]
- Hartley J. What does it say? text design, medical information and older readers . In Park DC, Morrell RW, Shifren K, eds. Processing of medical information in aging patients. Mahwah, NJ: Erlbaum. 1999 233–47. [ Google Scholar ]
- Matthews JR. Successful scientific writing: a step-by-step guide for biological and medical scientists . 2d ed. New York, NY: Cambridge University Press. 2000 [ Google Scholar ]
- Mulrow CD, Thacker SB, and Pugh JA. A proposal for more informative abstracts of review articles . Ann Intern Med . 1988 Apr: 108 ( 4 ):613–5. [ PubMed ] [ Google Scholar ]
- Clarke M, Oxman AD. eds. . Cochrane reviewers' handbook 4.0 [updated July 1999] . In: The Cochrane Library, issue 2 [database on CDROM]. The Cochrane Collaboration. Oxford, U.K.: Update Software. 2000 [ Google Scholar ]
- Schriver KA. Evaluating text quality: the continuum from text-focused to reader-focused methods . IEEE Trans Prof Comm . 1989 Dec. 32 ( 4 ):238–55. [ Google Scholar ]
- Berry DC, Michas IC, Gillie T, and Forster M. What do patients want to know about their medicines, and what do doctors want to tell them? a comparative study . Psychol and Health . 1997. 12 ( 4 ):467–80. [ Google Scholar ]
- Wilson R, Kenny T, Clark J, Moseley D, Newton L, Newton D, and Purves I. Ensuring the readability and efficacy of patient information leaflets . Newcastle, U.K.: Sowerby Health Centre for Health Informatics, Newcastle University. Prodigy Publication. 1998 no. 30. [ Google Scholar ]
- Harbourt AM, Knecht LS, and Humphreys BL. Structured abstracts in MEDLINE 1989–91 . Bull Med Libr Assoc . 1995 Apr. 83 ( 2 ):190–5. [ PMC free article ] [ PubMed ] [ Google Scholar ]
- Hartley J. Applying ergonomics to Applied Ergonomics: using structured abstracts . Appl Ergonom . 1999 Dec. 30 ( 6 ):535–41. [ PubMed ] [ Google Scholar ]
- Hartley J, Benjamin M. An evaluation of structured abstracts in journals published by the British Psychological Society . Brit J Educ Psychol . 1998 Sep. 68 ( 3 ):443–56. [ Google Scholar ]
- Haynes RB. More informative abstracts: current status and evaluation . J Clin Epidemiol . 1993 Jul. 46 ( 7 ):595–7. [ PubMed ] [ Google Scholar ]
- McIntosh N, Duc G, and Sedin G. Structure improves content and peer review of abstracts submitted to scientific meetings . European Science Editing . 1999 Jun. 25 ( 2 ):43–7. [ Google Scholar ]
- Scherer RW, Crawley B. Reporting of randomized clinical trial descriptors and the use of structured abstracts . JAMA . 1998 July 15. 280 ( 3 ):269–72. [ PubMed ] [ Google Scholar ]
- Taddio A, Pain T, Fassos FF, Boon H, Ilersich AL, and Einarson TR. Quality of nonstructured and structured abstracts of original research articles in the British Medical Journal, the Canadian Medical Association Journal and the Journal of the American Medical Association . Can Med Assoc J . 1994 May 15. 150 ( 10 ):1611–5. [ PMC free article ] [ PubMed ] [ Google Scholar ]
- Tenopir C, Jacso P. Quality of abstracts . Online . 1993 May. 17 ( 3 ):44–55. [ Google Scholar ]
- Froom P, Froom J. Deficiencies in structured medical abstracts . J Clin Epidemiol . 1993 Jul. 46 ( 7 ):591–4. [ PubMed ] [ Google Scholar ]
- Pitkin RM, Branagan MA. Can the accuracy of abstracts be improved by providing specific instructions? a randomized controlled trial . JAMA . 1998 Jul 15. 280 ( 3 ):267–9. [ PubMed ] [ Google Scholar ]
- Pitkin RM, Branagan MA, and Burmeister L. Accuracy of data in abstracts of published research articles . JAMA . 1999 Mar 24–31. 281 ( 12 ):1110–1. [ PubMed ] [ Google Scholar ]
- Hartley J.. Are structured abstracts more/less accurate than traditional ones? a study in the psychological literature. Journal of Information Science. 2000; 26 (4) [ Google Scholar ]
- Hartley J, Sydes M.. Are structured abstracts easier to read than traditional ones? J Res Reading. 1997; 20 (2):122–36. [ Google Scholar ]
- Hartley J, Sydes M, Blurton A.. Obtaining information accurately and quickly: are structured abstracts more efficient? J Info Sc. 1996; 22 (5):349–56. [ Google Scholar ]
- Booth A, O'Rourke AJ.. The value of structured abstracts in information retrieval from MEDLINE. Health Libr Rev. 1997; 14 (3):157–66. [ Google Scholar ]
- O'Rourke AJ. Structured abstracts in information retrieval from biomedical databases: a literature survey . Health Informatics J . 1997 Jan. 3 ( 1 ):17–20. [ Google Scholar ]
- Hartley J, Sydes M.. Which layout do you prefer? an analysis of readers' preferences for different typographic layouts of structured abstracts. J Info Sci. 1996; 22 (1):27–37. [ Google Scholar ]
- Hartley J. Typographic settings for structured abstracts . J Technical Writing and Communication . 2001 in press. [ Google Scholar ]
- Dronberger GB, Kowitz GT.. Abstract readability as a factor in information systems. J Am Soc Inf Sci. 1975; 26 :108–11. [ Google Scholar ]
- Roberts JC, Fletcher CH, and Fletcher SW. Effects of peer review and editing on the readability of articles published in Annals of Internal Medicine . JAMA . 1994 Jul 13. 272 ( 2 ):119–21. [ PubMed ] [ Google Scholar ]
Guidelines and Guidance
The Guidelines and Guidance section contains advice on conducting and reporting medical research.
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PRISMA for Abstracts: Reporting Systematic Reviews in Journal and Conference Abstracts
* E-mail: [email protected]
Affiliation Centre for Research in Evidence-Based Practice, Bond University, Gold Coast, Australia
Affiliation Centre for Statistics in Medicine, University of Oxford, Oxford, United Kingdom
Affiliations Centre for Statistics in Medicine, University of Oxford, Oxford, United Kingdom, INSERM, Paris, France
Affiliation National Center for Biotechnology Information, National Library of Medicine, Washington DC, United States of America
Affiliation James Lind Initiative, Oxford, United Kingdom
Affiliation Nordic Cochrane Centre, Copenhagen, Denmark
Affiliation Cochrane Editorial Unit, London, United Kingdom
¶ Membership of the PRISMA for Abstracts Group is provided in the Acknowledgments.
- Elaine M. Beller,
- Paul P. Glasziou,
- Douglas G. Altman,
- Sally Hopewell,
- Hilda Bastian,
- Iain Chalmers,
- Peter C. Gøtzsche,
- Toby Lasserson,
- David Tovey,
- for the PRISMA for Abstracts Group
Published: April 9, 2013
- Reader Comments
Citation: Beller EM, Glasziou PP, Altman DG, Hopewell S, Bastian H, Chalmers I, et al. (2013) PRISMA for Abstracts: Reporting Systematic Reviews in Journal and Conference Abstracts. PLoS Med 10(4): e1001419. https://doi.org/10.1371/journal.pmed.1001419
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.
Funding: This research was supported (in part) by the Intramural Research Program of the NIH, National Center for Biotechnology Information (National Library of Medicine). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: TL is employed by The Cochrane Collaboration. TL is an editor (unpaid) for the Cochrane Airways Group. The authors have declared that no other competing interests exist.
Abbreviations: PICOS, participants, interventions, comparators, outcomes, and study designs
Provenance: Not commissioned; externally peer reviewed.
- The abstract of a systematic review should provide a structured summary that enables a quick assessment of the review's validity and applicability, and easy identification in electronic searching.
- Despite published guidance on writing the abstract in the PRISMA Statement guiding the reporting of systematic reviews in general and elsewhere, evaluations show that reporting of systematic reviews in journal and conference abstracts is poor.
- We developed consensus-based reporting guidelines as an extension to the PRISMA Statement on good reporting of systematic reviews and meta-analyses in abstracts.
- The PRISMA for Abstracts checklist gives authors a framework for condensing their systematic review into the essentials for an abstract that will meet the needs of many readers.
When readers screen the title of an article, and parts of its abstract, they try to determine whether or not to devote their scarce time to reading on. Some may be screening literature to identify the articles that are systematic reviews. Thus, the main function of an abstract of a systematic review should be to signal its systematic methodology. For most readers, the findings described in the abstract will also be key, either as the sole part of an article that will be read, or to determine whether reading the full text is required. Abstracts of systematic reviews are very important, as some readers cannot access the full paper, such that abstracts may be the only option for gleaning research results. This can be because of a pay wall, low Internet download capacity, or if the full article is only available in a language not understood by the reader. Readers in countries where English is not the primary language may have access to an abstract translated to their own language, but not to a translated full text. Conversely, a large proportion of systematic reviews are published by health technology agencies in non-English speaking countries  , many of which provide only the abstract in English.
The predominance of the abstract in biomedical literature use is clear. Within queries to PubMed, most readers look only at titles; only half of searches result in any clicks on content  . The average number of titles clicked on to obtain the abstract or full text, even after retrieving several searches in a row, is less than five. Of those clicks, abstracts will be represented about 2.5 times more often than full texts of articles  . Even people going straight to a PDF or full text are likely to start, and perhaps end, with reading the abstract. The frequency of viewing full texts is somewhat higher among people searching the Cochrane Database of Systematic Reviews  , but the same pattern is clear. After the title, the abstract is the most read part of a biomedical article.
Abstracts can be useful for screening by study type  ; facilitating quick assessment of validity  ,  ; enabling efficient perusal of electronic search results  ,  ; clarifying to which patients and settings the results apply  ,  ; providing readers and peer reviewers with explicit summaries of results  ; facilitating the pre-publication peer review process  ; and increasing precision of computerised searches  ,  .
Structured abstracts were introduced in the medical literature about 25 years ago  –  . They provide readers with a series of headings, generally about the purpose, methods, results, and conclusions of the report, and have been adopted by many journals and conferences. They act as a prompt to the writer to give more complete information, and facilitate the finding of information by the reader.
Despite the adoption of structured abstracts, studies of the quality of abstracts of clinical trials have demonstrated that improvement is needed  ,  , and a study of systematic review abstracts demonstrated that the direction of the effect or association could not be determined in one in four abstracts from the general and specialty medical literature  . The PRISMA Statement  gives some guidance for abstracts, closely linked to commonly used headings in structured abstracts. After observing that the quality of abstracts of systematic reviews is still poor  , we decided to develop an extension to the PRISMA Statement to provide guidance on writing abstracts for systematic reviews. We also wanted to provide a checklist enabling the items suggested to fit into any set of headings mandated by a journal or conference submission.
Methods for Development of the Checklist
We established a steering committee (EMB, PPG, SH, DGA). In collaboration with the steering group of the PRISMA Statement  , we used the Statement to inform our selection of potential items for the checklist of essential items that authors should consider when reporting the primary results of a systematic review in a journal or conference abstract. The committee generated a list of items from PRISMA and other sources of guidance and information on structured abstracts and abstract composition and reporting  ,  ,  , which were found using a thorough search of the literature.
In preparation for a consensus meeting, we used a modified Delphi consensus survey method  to select and reduce the number of possible checklist items. Each item was rated by survey participants as “omit”, “possible”, “desirable”, or “essential” to include in the final checklist. From the first round of the survey, the ranked items were divided into three lists for the second round. The first list contained the items with the highest rankings, and participants for the second round were instructed that these would be contained in the checklist unless they received low rankings in the second round. The second list contained the items with moderate rankings, and participants were instructed that these items were likely to be removed from the checklist unless they received high rankings in the second round. The third list contained the items with low rankings, and participants were instructed that these items would be removed unless they received very high rankings in the second round.
For the third round of the Delphi survey, a draft checklist was presented, which included only the items ranked highest in rounds one and two. The five next highest-ranked items were then presented, giving participants an opportunity to choose to include these in the checklist as well.
One hundred and forty-seven participants, who were authors of research on abstracts, established authors of systematic reviews, methodologists or statisticians related to systematic reviews, and journal editors, were invited by email to complete the three rounds of the web-based survey. The response rate was 68% ( n = 100) for the first round. Only those who completed round one were invited to participate in rounds two and three. The response rate for round two was 80% ( n = 80) and for round three 88% ( n = 88).
The results of the survey were reported at a two-day consensus-style meeting on 13–14 October 2011, in Oxford, United Kingdom. Fifteen invited experts attended, most of whom had participated in the survey. The meeting began with a review of the literature about abstract structure and content, followed by a review of the checklist items as proposed by the survey respondents. Meeting participants discussed the items and agreed whether they should be included and how each item should be worded.
Following the meeting, the checklist was distributed to the participants to ensure it reflected the decisions made. This explanatory document was drafted and circulated through several iterations among members of the writing subcommittee who had all participated in the meeting. We developed this document using the template for the PRISMA Statement  , which in turn was based on the methods of the CONSORT Group  ,  .
Scope of PRISMA for Abstracts
The PRISMA for Abstracts checklist focuses on truthful representation of a systematic review in an abstract. We developed the checklist to help authors report all types of systematic reviews, but recognise that the emphasis is on systematic reviews of evaluations of interventions where one or more meta-analyses are conducted. Authors who address questions on aetiology, diagnostic test accuracy, or prognosis may need to modify items or include other items in their abstract to reflect the essentials of the full report.
The PRISMA for Abstracts Checklist
The checklist is shown in Table 1 . An explanation for each item is given below. Citations for the examples of good reporting are in Table 2 .
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Section 1: TITLE
Item 1: Title.
Identify the report as a systematic review, meta-analysis, or both.
Examples: 1a. “Systematic review and meta-analysis of the diagnostic and therapeutic role of water-soluble contrast agent in adhesive small bowel obstruction.”
1b. “Inhaled corticosteroids vs placebo for preventing COPD [chronic obstructive pulmonary disease] exacerbations: a systematic review and metaregression of randomized controlled trials.”
Explanation: The abstract should make it clear that the report is a systematic review, meta-analysis, or both (examples 1a and 1b). Search filters have been developed to identify systematic reviews  , but inclusion of the words “systematic review” or “meta-analysis” in the title may improve indexing and electronic searching.
We also suggest using informative titles that incorporate the PICOS approach (participants, interventions, comparators, outcomes, and study designs). This provides key information about the scope of the systematic review. As including all elements of the PICOS approach may make the title unwieldy, we suggest including the most important of these elements in the title. These might be the elements that make this review unusual, or that assist readers in searching for the review.
Section 2: BACKGROUND
Item 2: Objectives.
The research question including components such as participants, interventions, comparators, and outcomes.
Examples: 2a. “To assess the effect on survival of supportive care and chemotherapy versus supportive care alone in advanced NSCLC [non-small cell lung cancer].”
2b. “To evaluate the risk of serious asthma-related events among patients treated with formoterol.”
2c. “The objective of this study was to investigate the predictive value of C-reactive protein in critically ill patients.”
Explanation: Irrespective of the strength and nature of the results reported in the abstract, readers should be able to assess the questions that the review intended to address. The objectives in an abstract should convey succinctly the broad aims of the systematic review. Objectives should reflect what the review intended to evaluate, such as benefit (example 2a), harms (example 2b), association, predictive value (example 2c), of the intervention or exposure of interest and the population or context in which this is being studied.
Section 3: METHODS
Item 3: Eligibility criteria.
Study and report characteristics used as criteria for inclusion.
Examples – study characteristics: 3a. “We included randomised controlled trials testing the combination of long-acting ß 2 - agonists in combination with inhaled corticosteroids (ICS) versus the same or an increased dose of ICS for a minimum of at least 28 days in children and adolescents with asthma.”
3b. “… randomized trials of compression stockings versus no stockings in passengers on flights lasting at least four hours. Trials in which passengers wore a stocking on one leg but not the other, or those comparing stockings and another intervention were also eligible.”
Examples – report characteristics: 3c. “… studies published in English, French, Spanish, Italian and German between 1966 and July, 2008 [were included].”
3d. “We performed a literature search of trials using MEDLINE (January 1966–December 2001) … we retrieved English- and non-English-language articles for review… we searched for both published and unpublished trials…”
Explanation: One of the key features distinguishing a systematic review from a narrative review is the pre-specification of eligibility criteria for including and excluding studies. A clear description of these allows the readers to assess the applicability of the systematic review findings  . Study eligibility characteristics are likely to include the study questions (PICOS)—types of participants included in the studies (often based on a common clinical diagnosis), the intervention of prime interest and possibly the specific comparison intervention, the main outcome(s) being assessed—and acceptable study designs (examples 3a and 3b).
Eligibility criteria for reports may also include the language of publication, the publication status (e.g., whether to include unpublished materials and abstracts) and the year of publication (example 3d). This is important as inclusion, or not, of studies published in languages other than English (examples 3c and 3d), unpublished data, or older data can influence the estimates of effect or association in meta-analyses  ,  .
Item 4: Information sources.
Key databases searched and date of last search.
Examples: 4a. “PubMed, ERIC and Cochrane Reviews databases from January 1980 to November 2007 were searched for studies…”
4b. “We searched MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials (CENTRAL), other trial registries and product information sheets through June 2008.”
Explanation: The abstract should briefly indicate how thorough and up-to-date the search was by listing key databases searched, and the date range (example 4a) or date of last search (example 4b). We recommend that if there are three or fewer databases, list them all; otherwise list the three that provided the majority of included studies.
Item 5: Risk of bias assessment.
Methods for assessing risk of bias.
Example: 5a. “Risk of bias was assessed regarding randomisation, allocation sequence concealment, blinding, incomplete outcome data, selective outcome reporting, and other biases.”
Explanation: Problems in the design and conduct of individual studies can raise questions about the validity of their findings  . For example, reports of randomised trials with inadequate allocation sequence concealment are more likely to show exaggerated treatment effects  . And non-blinded assessors of subjective outcomes generate substantially biased effect estimates  ,  . It is therefore an important part of a systematic review to assess the validity of individual studies, and the risk that they will overestimate the true intervention effect. Authors should describe any methods they used to assess the risk of bias in the included studies (example 5a).
Many tools exist for assessing the overall risk of bias in included studies, including scales, checklists and individual components  . Most tools are scales in which various components of quality are scored and combined to give a summary score. This approach can be seriously misleading, however, and should be discouraged. A preferred approach requires authors to specify which individual methodological components they will assess and to provide a description and judgment for each component for each of the studies assessed  . For randomised trials, common components include: appropriate generation of the allocation sequence  , concealment of the allocation sequence  , blinding of participant and health care providers, blinding of outcome assessors  , assessment of incomplete outcome data  , and selective outcome reporting  .
Section 4: RESULTS
Item 6: Included studies.
Number and type of included studies and participants, and relevant characteristics of studies.
Examples: 6a. “We included 22 trials involving 101 507 participants: 11 trials reported on presumptive pneumococcal pneumonia, 19 on all-cause pneumonia and 12 on all-cause mortality. The current 23-valent vaccine was used in 8 trials.”
6b. “Eight studies included in this review (n = 586 patients, median PEDro score = 8.0/10) evaluated various parameters, including the duration of patients' symptoms (0–12 months), duty cycle (20% and 100%), intensity (0.1–2.0 W/cm2), treatment time per session (4.5–15.8 minutes), number of treatments (6–39), and total energy applied per treatment (181–8,152 J).”
Explanation: The number of studies, number of participants, and characteristics of the included studies (examples 6a and 6b) enable readers to gauge the validity and applicability of the systematic review's results. These characteristics might include descriptors of the participants (e.g., age, severity of disease), range of interventions used (e.g., dose and frequency of drug administration), and measurement of outcomes (e.g., follow-up times).
Item 7: Synthesis of results.
Results for main outcomes (benefits and harms), preferably indicating the number of studies and participants for each. If meta-analysis was done, include summary measures and confidence intervals.
Examples: 7a. “… CRT [cardiac resynchonization therapy] reduced all-cause mortality (6 trials, 4572 participants; risk ratio [RR], 0.83 [95% CI, 0.72 to 0.96]) and heart failure hospitalizations (4 trials, 4349 participants; RR, 0.71 [CI, 0.57 to 0.87]) without improving functional outcomes or quality of life.”
7b. “Six studies reported on maternal mortality and our meta-analysis showed a non-significant reduction (three randomised trials, relative risk 0.79, 0.53 to 1.05, P = 0.12; three non-randomised studies, 0.80, 0.44 to 1.15, P = 0.26).”
7c. “Eight studies presented adjusted odds ratios, ranging from 0.3 to 0.9, suggesting a reduced likelihood of self-reported sharing of non-N/S [non-needle/syringe] injecting paraphernalia associated with use of NSP [needle and syringe exchange programmes] or SIF [safer injection facilities].”
Explanation: The results for the main outcomes should be given in the abstract. If meta-analyses have been done, include for each the summary measure (estimated effect) and confidence interval. If the intention had been to perform meta-analysis, but no meta-analysis was done for one or more main outcomes, the reasons should be stated (e.g., heterogeneity too great).
The abstract should make clear the protocol-defined, pre-specified importance of each outcome reported, and should not report only those outcomes that have statistically significant or clinically important results.
Where possible, given space limitations, the number of studies and participants for each main outcome should be stated, particularly if only a small proportion of the total number of studies or patients in the systematic review contributed information on a particular outcome.
If there are no summary measures, some numerical data may still be given (example 7c), although authors should be wary of making this in the form of “vote counting” where the number of “positive” and “negative” studies is given. Vote counting takes no account of weighting of studies according to the amount of information they contain  .
Item 8: Description of effect.
Direction of the effect (i.e., which group is favoured) and size of the effect in terms meaningful to patients and clinicians.
Examples: 8a. “Radial access reduced major bleeding by 73% compared to femoral access (0.05% vs 2.3%, OR 0.27 [95% CI 0.16, 0.45], P<0.001).”
8b. “Length of hospital and critical care unit stay were both modestly reduced in the tested group compared with the control group, with a mean difference of −1.22 day (CI, −2.31 to −0.14 day) and −0.56 day (CI, −1.06 to −0.05 day), respectively.”
8c. “A small difference was found between acupuncture and placebo acupuncture: standardised mean difference −0.17 (95% confidence interval −0.26 to −0.08)… [in favour of acupuncture]…, corresponding to 4 mm (2 mm to 6 mm) on a 100 mm visual analogue scale.”
Explanation: The results should summarise the main outcomes in words and numbers. The wording should indicate the direction of the effect (e.g., lower, fewer, reduced; greater, more, increased) and the size of the effect using familiar units such as percentages, days, or kilograms. Example 8a makes clear the size of the effect even for readers who have difficulty interpreting relative risks and confidence intervals. When a percentage is used, the baseline risk should also be shown, which allows the reader to see what the absolute benefit or harm is, and calculate whichever measures they choose (example 8a). Authors should take care to make it clear whether the reported measure is an absolute or a relative one (e.g., where percentage is used as the units of measurement). Where possible, continuous outcome measures should be expressed in familiar units (example 8b), particularly when the standardised mean difference is used (example 8c).
Section 5: DISCUSSION
Item 9: Strengths and limitations of evidence.
Brief summary of strength and limitations of evidence (e.g., inconsistency, imprecision, indirectness, or risk of bias, other supporting or conflicting evidence).
Examples: 9a. “Four potentially eligible trials were not included in the meta-analysis because mortality data by age group were not available.”
9b. “All trials were open label, which may introduce bias. Most of the trials were of 24 weeks' duration or less, limiting assessment of long-term safety.”
9c. “Meta-analyses for some outcomes had large statistical heterogeneity or evidence for publication bias. Only 11 trials followed outcomes beyond 12 months.”
9d. “Meta-regression showed that small, poor-quality studies that assessed outcomes soon after radiocontrast administration were more likely to suggest benefit (P<0.05 for all).”
Explanation: The abstract should briefly describe the strengths and limitations of the evidence across studies  . Limitations may include: risk of bias common to many or all studies, such as lack of blinding for subjective outcomes (example 9b) or unavailability of data (example 9a); inconsistency of effect or association, as demonstrated by high heterogeneity (examples 9c and 9d); imprecision, e.g., due to few events or small sample sizes; indirectness of the evidence, such as the use of an intermediate or short-term outcome (examples 9b and 9c); and likely publication bias (example 9c). Potential strengths of the overall body of evidence that might apply for a particular outcome of a systematic review include: a large effect (example 8a); demonstration of a dose-response relationship (example 10a, below); and that all biases would be likely to reduce the effect rather than increase it. One or more of these strengths and limitations may apply to each of the outcomes of the systematic review being described in the abstract. Some of this information may be combined with item 6, above, when describing the included studies, however a summary of the overall strengths and limitations of the evidence might also be helpful.
Item 10: Interpretation.
General interpretation of the results and important implications.
Examples: 10a. “Travel is associated with a nearly 3-fold higher risk for VTE [venous thromoboembolism], with a dose-response relationship of 18% higher risk for each 2-hour increase in travel duration.”
10b. “Housing improvements, especially warmth improvements, can generate health improvements; there is little evidence of detrimental health impacts. The potential for health benefits may depend on baseline housing conditions and careful targeting of the intervention. Investigation of socioeconomic impacts associated with housing improvement is needed to investigate the potential for longer-term health impacts.”
10c. “The cumulative evidence is now conclusive that the addition of cardiac resynchronization to optimal medical therapy or defibrillator therapy significantly reduces mortality among patients with heart failure.”
Explanation: Remembering that some readers may struggle with interpreting the statistical results, an overall summary of the main effects—positive or negative—should be given (example 10a). This could include an indication of what is clear (example 10c), what important uncertainties remain (example 10b), and whether there is ongoing research addressing these.
If there is insufficient evidence from well-conducted studies to answer the review's question, this should be made clear to the reader. When the results are not statistically significant, authors should distinguish between those where there is insufficient evidence to rule out a difference between treatments (wide confidence interval), and those which have sufficient evidence that an important difference is unlikely (narrow confidence interval).
If the conclusions of the review differ substantially from previous systematic reviews, then some explanation might also be provided. Reference could be made to known ongoing studies that have the potential to change the result of the review. Possible implications for policy and practice should be stated.
Section 6: OTHER
Item 11: Funding.
Primary source of funding for the review.
Examples: 11a. “This work was supported, in part, by the Program in Reproductive and Adult Endocrinology, NICHD, NIH, Bethesda, MD. The authors have no competing interests to declare.”
11b. “Funding: National Institute for Health Research Programme Grant for Applied Research.”
Explanation: Studies of the relationship between pharmaceutical company funding and results of clinical trials have shown that sponsored studies are more likely to have outcomes favouring the sponsor  ,  . This is also the case for systematic reviews  . Therefore, the abstract should indicate whether the sponsor of the research or the researchers might have a conflict of interest in respect of the findings of the systematic review, for example, as the manufacturer of the intervention being evaluated (examples 11a and 11b). The abstract should include the main source of funding for the systematic review, whether from host institutions or from external bodies.
Item 12: Registration.
Registration number and registry name.
Examples: 12a. “PROSPERO registration: CRD42011001243.”
12b. “PROSPERO 2011:CRD42011001329.”
Explanation: Registration of systematic reviews provides a record of reviews that have been initiated, even if they have not been published. It is therefore a means of alerting researchers to systematic reviews that are in progress, and serves as a public record of the proposed systematic review. It also helps to detect reporting bias by enabling better identification of unpublished systematic reviews, and also to compare the methods or outcomes reported in published reviews with those originally proposed in registered protocols  . The abstract should record the name of the database with which the review is registered, and the registration number. Cochrane reviews are an exception to this requirement, as they are preceded by a peer reviewed protocol that is published in the Cochrane Library and can be downloaded from there.
The title of a systematic review is its first signal of its relevance to potential readers. Few titles will entice a reader to invest additional time, but when they do, they ordinarily start—and quite often end—with the abstract. The first impression is therefore crucial.
We strongly recommend the use of structured abstracts for reporting systematic reviews, as does the PRISMA Statement  . We recognise that journals have developed their own set of headings that are considered appropriate for reporting systematic reviews, and it is not our intention to suggest changes to these headings, but to recommend what should be reported under them. The order of items and the headings are therefore flexible. For example, the strengths and limitations may be stated at the end of the Results, under a separate heading, or with the Discussion or Conclusions, depending on journal requirements. It may also be possible to combine items from the checklist into one sentence. For example, limitations may be combined with a description of the included studies (i.e., items 6 and 9 from the checklist).
We have suggested reporting a minimum set of items. We do not advocate that abstracts replace full articles in informing decision making, but we recognise that for many time-pressed readers, or for those with limited access to the full texts of reports, it is important that abstracts contain as much information as is feasible within the word limit of abstracts. Indeed, for readers who do not understand the language of publication of the article, the translated abstract may have far more relevance than the full-text article.
A checklist is not sufficient to ensure good abstract writing. For example, the abstract should clearly and truthfully reflect the full report, and not selectively report results that are statistically significant while not referring to those that were not. Similarly, the abstract should only draw conclusions that are substantiated by data from the full report and analyzed as described in the protocol, rather than selectively emphasising interesting results that were a minor or ad hoc component of the analysis. In brief, the abstract should be an unbiased representation of the full report. We also suggest that peer and editorial review processes related to the abstract should explicitly check this.
A particularly difficult area is the Discussion section of an abstract. The checklist includes two items with several elements. We suggest that authors let the reader know whether they feel their question has been answered, or whether there is still uncertainty before presenting practice and policy implications. These statements should be clearly backed by the results given in the abstract, and by presentation of the strengths and limitations of the evidence in the review.
We encourage journals and conference organisers to endorse the use of PRISMA for Abstracts, in a similar way to CONSORT for Abstracts  . This may be done by modifying their instructions to authors and including a link to the checklist on their website. It has been demonstrated that the number of checklist items reported is improved in journals that require checklist completion as part of the submission process  .
Abstracts should not replace full articles in informing decision making, but for time-pressed readers and those with limited access to full text reports, the abstract must stand alone in presenting a clear and truthful account of the research. The PRISMA for Abstracts checklist will guide authors in presenting an abstract that facilitates a quick assessment of review validity, an explicit summary of results, facilitates pre-publication or conference selection peer review, and enables efficient perusal of electronic search results.
We dedicate this paper to the memory of Alessandro Liberati who, among many important achievements, was instrumental in the development and implementation of the PRISMA Statement, and had many thoughtful insights to offer at the PRISMA for Abstracts consensus meeting.
We are grateful to the other participants of the consensus meeting for their time and interest: Martin Burton, UK Cochrane Centre, UK; Trish Groves, BMJ, UK; Alessandro Liberati, Italian Cochrane Centre, Italy; Cynthia Mulrow, Annals of Internal Medicine , USA; Melissa Norton, PLOS Medicine , UK; Elizabeth Wager, Sideview, UK; and to everyone who responded to the PRISMA for Abstracts survey.
Analyzed the data: EMB. Wrote the first draft of the manuscript: EMB. Contributed to the writing of the manuscript: EMB PPG DGA SH HB IC PCG TL DT. ICMJE criteria for authorship read and met: EMB PPG DGA SH HB IC PCG TL DT. Agree with manuscript results and conclusions: EMB PPG DGA SH HB IC PCG TL DT.
- View Article
- Google Scholar
- 2. Dogan RI, Murray GC, Neveol A, Lu Z (2009) Understanding PubMed user search behavior through log analysis. Database: Article ID bap018. https://doi.org/10.1093/database/bap018 .
- 13. Murphy MK, Black NA, Lamping DL, McKee CM, Sanderson CFB, et al. (1998) Consensus development methods, and their use in clinical guideline development. Health Technol Assessment 2 (3).
- 21. Schulz KF, Grimes DA (2006) The Lancet handbook of essential concepts in clinical research. London: Elsevier.
- 24. Als-Nielsen B, Gluud LL, Gluud C (2004) Methodological quality and treatment effects in randomized trials: a review of six empirical studies. 12th Cochrane Colloquium, Ottawa (Canada).