Systematic Review and Evidence Synthesis

Librarians are experts trained in literature searching and evidence synthesis methodology and most guidelines recommend you work with a librarian in developing your search strategies. The goal of an evidence synthesis search is to retrieve all results that are relevant to your topic; missed relevant studies can lead to bias or incorrect conclusions. Because evidence synthesis searches can be quite extensive and retrieve large numbers of results, an important aspect of systematic searching is limiting the number of irrelevant results that need to be screened. Studies in a variety of disciplines have found that evidence synthesis publications with a librarian co-author do a better job of reporting their search methodologies and include a more comprehensive, robust search (e.g., Koffel, 2015, Marsalis & Brown, 2020, Rethlefsen et al., 2015). Partnering with a librarian will save you time and improve the quality of your review.

The level of involvement can vary from advising on databases to search and reviewing keywords, to acting as a co-author, conducting the searches and writing the relevant portion of the Methods section. 

A librarian will help you select databases relevant to your topic and create a detailed search strategy. You also want to search outside the normal academic publishing model. This is commonly known as "grey literature." This might involve searching conference proceedings, browsing websites, and contacting experts in the field. The grey literature is important because negative results are less likely to be published. This will affect the reliability of your findings.

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It is important that you keep detailed records as you search. PRISMA-S provides reporting guidelines related to your search. You will need to document details such as:

• databases you searched, the platform, and what years those databases covered;

• dates the searches were first run and updated;

• details of strategies used, including search terms and operators; and

• numbers of results obtained.

Using Boolean logic is an important component of writing a search strategy: 

• "AND" narrows the search, example: children AND exercise

• "OR" broadens the search, example: (children OR adolescents) AND (exercise OR diet) 

• "NOT" excludes terms, example: exercise NOT diet 

• "*" at the root of a word finds all forms of that word, example: (child* OR adolescen*) AND (exercise* OR diet*)

• parentheses ensure all terms will be searched together as a set 

quotations around a phrase searches that exact phrase, example: (child* OR adolescen* OR "young adult*")

The syntax and command structures used in literature searching varies between databases and what company's platform one is using. The basics for our most commonly used platforms are listed here, but you should also consult the help screens available when planning your search strategies.

Boolean Operators

Phrase Searching*

Truncation

Proximity

Barrick, K., & Riegelman, A. (2021). Phrasing in reproducible search methodology: The consequences of straight and curly quotation marks. College & Research Libraries, 82(7), 978. https://doi.org/10.5860/crl.82.7.978

Koffel, J. B. (2015). Use of recommended search strategies in systematic reviews and the impact of librarian involvement: a cross-sectional survey of recent authors. PloS One, 10(5), e0125931. https://doi.org/10.1371/journal.pone.0125931 

Marsalis, S. & Brown, E. (2020, January). Adoption of systematic and related review methods in social work and reporting quality of underpinning searches [Paper presentation]. Society for Social Work and Research Annual Meeting, Washington, D.C.

Rethlefsen, M. L., Farrell, A. M., Trzasko, L. C. O., & Brigham, T. J. (2015). Librarian co-authors correlated with higher quality reported search strategies in general internal medicine systematic reviews. Journal of Clinical Epidemiology, 68(6), 617-626. https://doi.org/10.1016/j.jclinepi.2014.11.025