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Research Guides

Systematic Reviews and Related Evidence Syntheses

Search Strategies

The table below illustrates the process from a research question to databases and search parameters. When planning your search strategies, also check the systematic review search conduct standards for your disciplines. For social sciences, for instance, use Campbell Collaboration (MECCIR) Conduct Standards and Searching for Studies: A Guide to Information Retrieval for Campbell Systematic Reviews (Feb 2017) as guides.

The table image was captured from a tutorial video by Yale University Library.


PRELIMINARY SEARCH - After determining the research question and a method of the systematic review,

  • Perform a scoping search with the relevant databases to find out
    (1) if anyone else has done a systematic review on the same topic before.
    (2) if there are enough primary studies available for your systematic review.
    (3) the scope of the qualified studies, key authors, key studies and key search terms.
    (4) the background literature that may help to refine your research question and set inclusion/exclusion criteria,

FULL-SCALE SEARCH - Systematically search for studies using predetermined criteria.

  • Finalize selection of databases to search. Consult your research librarian.
  • Develop a set of search strategies using keywords, subject headings to construct search queries.

    Keywords are natural language search terms commonly used for basic searches. Unlike subject heading searches, a keyword search will not automatically deploy the use of synonyms or the related terms about a given topic. To include synonyms to broaden your keyword search you must key in each term such as assessment or evaluation or appraisal.

    Subject Headings - Controlled vocabularies such as MeSH for PubMed, MH for CINAHL, DE for ERIC and SU or DE for PsycINFO are the standardized terms or terms on-topic used to describe subject contents. Subject headings are unique to a database. In order to produce consistent results for systematic reviews one must utilize subject headings in search.

    “Pain Management” [Mesh]  -- PubMed
    MH "Pain Management"       -- CINAHL
    DE “Pain Management”     ---- PsycINFO

    Tutorials: Subject Terms vs. Keywords  |  MeSH Vocabulary  |

    Boolean Operators  - Combine search concepts with Boolean operators (AND, OR, NOT)
    - AND includes all search terms but will narrow the search.                   
    - OR includes either of the search terms and will broaden the search.  
    - NOT excludes certain search terms.                                                     

    Example I
    survey AND college
    (survey OR questionnaire) AND ( college OR university OR higher education)
    Survey NOT interview

    Tutorial: Boolean Operators 

    Example II <ERIC Database>
    Search for systematic reviews on mathematics. There are two concepts in this query with which to build two search strings consisting of subject descriptors, synonyms, keywords, Boolean and proximity connectors.

    Concept 1 - Math. Subject descriptors and keywords in Title / Abstract connected with OR.

    ((DE “Mathematics” OR DE “Algebra” OR DE “Arithmetic” OR DE “Calculus” OR DE “Geometry” OR DE “Probability” OR DE “Statistics” OR DE “Trigonometry”) OR  (TI ( math* OR algebra OR geometry OR calculus OR precalculus OR pre-calculus OR trigonometry ) OR AB ( math* OR algebra OR geometry OR calculus OR precalculus OR pre-calculus OR trigonometry ))


Concept 2 - Systematic Reviews. Subject descriptors, keywords in Title / Abstract and proximity connector n# connected with OR.

( ( DE “Meta Analysis” OR DE “Literature Reviews” ) OR (TI ( (literature or systematic) n2 review) or (meta n1 analysis) or (research n2 synthesis) or (evidence n2 synthesis) ) OR AB ( (systematic or literature) n2 review) or (meta n1 analysis) or (research n2 synthesis) or (evidence n2 synthesis) )

Video Tutorials:  How to Search PubMed <Yale> |  How to Search CINAHL<Yale> | PsycINFO <Youtube> |

Grey Literature

  •  "Grey literature is produced outside of traditional publishing and distribution norms. This can included, among other things, white papers, government publications, working papers, preprints, unpublished trial data, and conference proceedings and abstracts. Grey literature can be found in some citation databases, as well as databases dedicated to grey literature" <University of Pittsburgh>

    How Do I Search the Grey Literature? <Cornell U>

    Databases:  ProQuest Dissertation & Theses  | Center For Research Libraries |

  • Search Filter or Hedges:
    "Filters and hedges are prefab search strategies that can help you quickly search databases for articles on certain topics or those with certain study designs. This tutorial introduces the concept of filters and hedges, their validation process, and where to find existing filters and hedges." <Yale University Library>

    Tutorial: How to use filters and hedges |