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Systematic Reviews & Evidence Synthesis Methods

A detailed, step-by-step guide to the first several stages of an evidence synthesis review.

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About This Guide

This research guide provides an overview of the evidence synthesis process, guidance documents for conducting evidence synthesis projects, and links to resources to help you conduct a comprehensive and systematic search of the scholarly literature. Navigate the guide using the tabs on the left.

"Evidence synthesis" refers to any method of identifying, selecting, and combining results from multiple studies. A systematic review is a type of evidence synthesis. We use the term evidence synthesis to better reflect the breadth of methodologies that we support, including systematic reviews, scoping reviews, evidence gap maps, umbrella reviews, meta-analyses and others.

Note: Librarians at UC Irvine Libraries have supported systematic reviews and related methodologies in STEM fields for several years. As our service has evolved, we have added capacity to support these reviews in the Social Sciences as well.

UC Irvine's Evidence Synthesis Service

The Institute of Medicine recommends that a librarian or information specialist be involved in the systematic review process. In fact, a study published in the Journal of Clinical Epidemiology shows that librarian involvement in systematic reviews improves both the quality and the reproducibility of the literature search.

UC Irvine's Evidence Synthesis Service can help you:

  • Find existing evidence syntheses and protocols to inform your own protocol development.
  • Identify relevant databases and grey literature resources in which to conduct literature searches related to your topic.
  • Design and implement complex, comprehensive search strategies to maximize retrieval of relevant studies.
  • Create search alerts to ensure that new studies are found while the evidence synthesis is in progress.
  • Use citation management software, such as Endnote, Zotero, and Mendeley to manage the study gathering and selection process.
  • Understand how to retrieve full-text articles, and track down hard-to-find full text articles for screening and review.
  • Write the methods section of your review for publication, to ensure clarity and transparency of the search process.

How Librarians Can Help

The Evidence Synthesis Service at UCI Libraries focuses on consulting. If a librarian is interested in getting more involved in your project, they may also be a co-author (see more about that in the boxes at the bottom of this page), but that is up to the capacity of each individual librarian.


As a consultant, a librarian can step in at different points of your evidence synthesis review. Librarians can:

  • provide background information and resources on the evidence synthesis process,
  • recommend databases, protocol registration platforms, and citation management software, and
  • suggest edits for your search strategy.

This option is a limited time commitment.


If appropriate, a librarian may also provide a workshop to a small team or cohort. Workshop content can be worked out between the librarian and coordinator, and may include outlining the basics of evidence synthesis, the basics of developing a search strategy, or how to search for grey literature, for example.


Co-authoring is a more substantial commitment, as a librarian will typically devote more than a year to partner with you on your evidence synthesis review. Co-authorship is not part of UCI Libraries Evidence Synthesis Service, but at the discretion of the librarian.

If a librarian has capacity and interest to co-author, the librarian will be more hands-on and can:

  • comment on the protocol,
  • select databases and grey literature resources,
  • write the search strategy,
  • translate searches to syntax of all databases,
  • perform searches and export them to citation management software,
  • perform deduplication, or train your team on the process,
  • set up in article screening software, and
  • write a portion of the methods section specific to searching.

See the "Librarian as Co-author: Tasks and Timelines" box below to learn more.

Librarian as Co-author: Tasks and Timelines

If a librarian has capacity and interest they can be heavily involved in the evidence synthesis process, however it is recommended that the disciplinary experts on the author team manage certain steps that require specific content-area and quantitative methods expertise. Librarians who write the search methodology section of the synthesis should be included as a co-author. Librarians who collaborate on search strategy formation and/or citation management should be acknowledged in the final publication. See Defining the Role of Authors and Contributors by The International Committee of Medical Journal Editors to learn more about the role of authors and contributors.

An evidence synthesis review will typically require a year or more to complete, and librarians’ availability may vary, so please plan ahead and reach out to us as early as you can.

Below is a detailed chart that breaks down the steps of a traditional evidence synthesis review and the librarian co-author’s potential contributions.

Note: these time estimates may vary depending on the project, and some steps may happen concurrently.

Timeline for librarian involvement
Steps in a traditional evidence review Estimated time investment Potential contribution of librarian co-author

1.  Assemble evidence synthesis review team and select project manager

Varies Provide guidance

2. Identify appropriate review methodology

2 weeks Provide guidance
3. Define research question 2 weeks Provide information on appropriate question frameworks (e.g. PICO)
4. Define inclusion/exclusion criteria 1 week Provide guidance
5. Select databases 1 week Suggest appropriate databases
6. Select grey literature resources 1 week Suggest grey literature resources
7. Write search strategy for primary database 2-4 weeks Lead writing of the search strategy
8. Write and register protocol (written compilation of previous steps) Varies Provide comments on protocol and guide protocol registration process
9. Translate search strategy to syntax 2 of all databases (including grey literature) 2-4 weeks Translate search strategy
10. Search and export results into citation management software 2 weeks Perform searches and export results
11. De-duplicate results 2-4 weeks Perform de-duplication, or train your team on the process
12. Title and abstract screening 2-3 months * Recommend article screening software and advise on use of software
13. Retrieve full-text articles 1 month * Train team on full-text article retrieval
14. Full-text screening 2-3 months * Provide guidance
15. Risk-of-bias assessment 2-3 months Provide guidance
16. Data extraction 2-3 months Provide guidance
17. Meta-analysis or synthesis of results 2-3 months Provide guidance
18. Write the manuscript 2-3 months Write information retrieval portion of the methods section


* Timeframe can vary significantly depending on number of citations identified for screening.

Video: Working with a librarian on evidence synthesis (6:30 minutes)

Attributions & Gratitude

This guide was adapted from Cornell University Library's A Guide to Evidence Synthesis and the University of Minnesota Library's Systematic review and evidence synthesis services webpage. Throughout this guide, there are links to numerous other resources compiled by other librarians or researchers. We are grateful for their incredible work in creating such detailed content that follows the process of working through evidence synthesis in such a structured way.