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Systematic Reviews: Search strategies

A guide to assist staff and students undertaking systematic reviews

Search strategies

Sensitivity versus precision

"Searches for systematic reviews aim to be as extensive as possible in order to ensure that as many of the relevant studies as possible are included in the review. It is, however, necessary to strike a balance between striving for comprehensiveness and maintaining relevance when developing a search strategy."

Cochrane handbook Chapter 4 Searching for and selecting studies, 4.43 Sensitivity versus precision.


To increase sensitivity in your search:

  • Minimize the number of concepts, but maximize the number of relevant search terms within each concept.
  • It is useful to start with a broad search using the Population and Intervention elements of the PICO. 
  • Look for more synonyms for each concept and combine with OR
  • Include both database subject headings (e.g. MeSH) and keywords in the search.
  • 'Explode' subject headings where appropriate - this will include narrower, more specific subject headings.
  • Avoid using 'focus' or 'subheading' options - these are offered as ways to improve search precision in databases such as Medline, PsycINFO, and CINAHL. These elements are subjectively assigned by a human indexer which means they can be susceptible to error or bias.
  • Limiting the search too far might risk losing significant studies. Studies that don't meet the selection criteria for selecting studies can be excluded in the selection process.


Systematic Approaches to Searching the Health Science Literature - video tutorials

A series of video tutorials by the Cushing/Whitney Medical Library at Yale University, on how to systematically search the health sciences literature. The videos will mainly focus on systematic searches required by a "systematic review". The goal of these tutorials is to ensure that your search is comprehensive, methodical, transparent and reproducible, so that your conclusions are as unbiased and closer to the the truth as possible.

Click on links to individual videos below or to view the list of (11) videos go to Cushing/Whitney Medical Library

PRESS - Peer Review of Electronic Search Strategies

Text mining tools

Text mining tools can assist you to establish appropriate keywords and subject headings for your topic.

Some tools include:


Kable, A. K., Pich, J., & Maslin-Prothero, S. E. (2012). A structured approach to documenting a search strategy for publication: a 12 step guideline for authors. Nurse Education Today, 32(8), 878–878.