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Writing a Systematic Review

Glossary of Terms


An international organization for evidence synthesis, especially systematic reviews and meta‐analyses in relation to health (

Eligibility (Inclusion/Exclusion) Criteria

In systematic reviews, large numbers of search results get winnowed down to a comparatively small number of works that will be analyzed. The framing of the research question, and what the researchers deem relevant, constitute the criteria that works must meet to be eligible for comparison. Common criteria include: language, publication date, geography, characteristics of the population studied, intervention (or exposure), and study design.

Grey Literature

"Grey literature stands for manifold document types produced on all levels of government, academics, business, and industry in print and electronic formats that are protected by intellectual property rights, of sufficient quality to be collected and preserved by libraries and institutional repositories, but not controlled by commercial publishers, i.e. where publishing is not the primary activity of the producing body." (Schopfel, J. Towards a Prague definition of grey literature. Paper presented at the 12th Intl. Conference on Grey Literature, Prague, Dec. 6-7, 2010.)


"Medical Subject Headings: a thesaurus of medical terms used by many databases and libraries to index and classify medical information."(CEBM)


"Works consisting of studies using a quantitative method of combining the results of independent studies (usually drawn from the published literature) and synthesizing summaries and conclusions which may be used to evaluate therapeutic effectiveness, plan new studies, etc. It is often an overview of clinical trials. It is usually called a meta-analysis by the author or sponsoring body and should be differentiated from reviews of literature." (National Library of Medicine, MeSH Thesaurus)


An acronym for: Population, Intervention (indicator/exposure/diagnostic tool), Comparison/control, and Outcome. PICO is often used to generate a clinical question for a review of the health literature.


PRISMA is an evidence-based minimum set of items for reporting in systematic reviews and meta-analyses. PRISMA focuses on the reporting of reviews evaluating randomized trials, but can also be used as a basis for reporting systematic reviews of other types of research, particularly evaluations of interventions. (PRISMA)


PROSPERO is an international database of prospectively registered systematic reviews in health and social care, welfare, public health, education, crime, justice, and international development, where there is a health-related outcome. (PROSPERO) See this page for other places to register your protocols.


"The plan or set of steps to be followed in a study. A Protocol for a systematic review should describe the rationale for the review, the objectives, and the methods that will be used to locate, select, and critically appraise studies, and to collect and analyse data from the included studies." (Cochrane)


"The degree to which results obtained by a measurement procedure can be replicated. Lack of reliability can arise from divergences between observers or measurement instruments, measurement error, or instability in the attribute being measured." (Cochrane)

Supplementary/Hand Searching

Supplementary or hand searching refers to identifying relevant literature by other means outside of one's search strategy. Methods might include examining specific relevant journals and websites, or "snowballing" by either mining the bibliographies of exemplary articles for other relevant references or looking for other articles that have cited the exemplary articles. (See also

Systematic Search Strategy

A systematic search strategy provides readers with a recipe to reproduce the authors' searches. Think of it as a document that includes the exact terms and search fields used, Boolean operators, and any special features employed, for each database or resource that is searched. Systematic reviews need sensitive search strategies--search strategies that have a high recall for the relevant literature.

For more information, see V. Nagendrababu,  P. Dilokthornsakul, P. M. H. Dummer, et. al. (February 2020). Glossary for systematic reviews and meta‐analyses. International Endodontic Journal. Volume53, Issue2: 232-249.


This guide was adapted from Systematic Reviews by University of Texas Libraries ( which is licensed under a Creative Commons Attribution-NonCommercial 2.0 Generic License.