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Systematic Reviews

This is a guide for learning about systematic reviews.

Search strategies and techniques

  • Identify search terms based on key concepts of your research question.
  • Create a table to record search terms and develop appropriate synonyms.
  • Use natural language (free-text) as well as controlled vocabulary terms (subject terms). Subjects terms will differ according to the databases being used.
  • Use Boolean operators (AND, OR, NOT) to combine your search terms and increase specificity. 
  • Use database limiters and filters to refine search results.
  • Review search strategy and search strings with a librarian.

Translating search strategies

In order to ensure that the search in support of a systematic review is comprehensive and eliminates bias, it is important to systematically search multiple databases. Besides differing in terms of subject headings, not all databases accept the same search "syntax." Search syntax must be "translated" between databases. While this translation has traditionally been done manually, there are several new tools that have been developed to automate this process. 

Search Syntax Translation Resources 

  • Polyglot search tool. This is a tool for translating search strings across multiple databases. 
  • MEDLINE Transpose. Use this to translate your MEDLINE (PubMed) search to MEDLINE (Ovid) format or vice versa. 
  • Database Syntax Guide. A guide to translating syntax for multiple databases. From Cochrane. 

Note: After the syntax has been translated, it is necessary to identify and search on the relevant subject headings for each database. 

For more information see Cornell University Library: Translating Search Strategies

Grey literature

  • Searching academic databases alone will not ensure comprehensiveness of a systematic review. It is important to also identify literature outside of academic journals, which is referred to as grey literature. 
  • Grey literature includes conference proceedings, reports, unpublished studies, white papers and working papers or preprints. This literature is not found in peer-reviewed academic journals.
  • Finding grey literature requires different search strategies than those used in searching  academic journal databases.
  • Discuss search strategies with a librarian.

Additional search strategies

  • Hand searching: manual checking of complete journal issues.
  • Snowballing: reviewing references of retrieved documents. Also know as citation tracing, or citation harvesting.
  • Forward searching: looking at cited by references