UWM Libraries Research and Course Guides: Evidence Synthesis Reviews: Search Strategies

What is a Systematic Search?

A systematic search is used in Systematic, Rapid, Umbrella, or Scoping Review.

The aim of a systematic search is to:

locate every record of evidence on a given topic
Recall a high number of relevant records while maintaining focus on topic
use multiple databases, registers, and websites to locate the evidence
locate evidence using a variety of techniques (extended boolean searching, index terms, hand searching, cited reference searching)

Report your search strategy

Document your search strategy in your protocol (transparency) and document the full search strategy for at least one database (transparency & reproducibility). See the PRISMA-Search checklist for reporting items.

PRISMA Search
The PRISMA extension for searching was published in 2021. The checklist includes 16 reporting items, each of which is detailed with exemplar reporting and rationale.

Harari, M. B., Parola, H. R., Hartwell, C. J., & Riegelman, A. (2020). Literature searches in systematic reviews and meta-analyses: A review, evaluation, and recommendations. Journal of Vocational Behavior, 118, 103377. https://doi.org/10.1016/j.jvb.2020.103377

Work with a Librarian!

It is highly recommended to work with a librarian when identifying information sources and developing a search strategy. Librarians may help with evidence synthesis reviews by:

Advising on registration protocols
Identifying information sources including databases, repositories, and grey literature and specific collections that will need to be documented in the protocol and reported in the final paper
Developing a search strategy for the main database to be searched and/or advise on translating the search strategy for different database platforms
Citation management, de-duplication, and full-text retrieval
Serving as a co-author, writing up search strategy in the methodology section of the paper

Design a Search Strategy

A search strategy includes the databases, information sources, and terms searched in the review.

Select databases

Identify 2 or more databases to search based on your topic and subject area. Include the database name and platform in your protocol and methods section. For example, MEDLINE (EBSCOhost) and Web of Science Core Collection (Clarivate). Design and test your search strategy in one database to include in your protocol, then "translate" the syntax and controlled vocabulary terms for the other databases.

See databases by subject or ask a librarian for help.

Planning and Tracking Search Queries: Research log
Plan your research strategies, using this worksheet to develop your concepts and decide on appropriate commands to combine them. The next pages have a research log to track your search results. Successful searching often involves searching multiple databases, and it helps to keep track as you refine your search.

Choose search terms

You search strategy should include both keywords and appropriate controlled vocabulary terms.

Identify the key concepts of your research questions (2-4) and related keywords. Locate 2-3 representative articles that you expect to see in the results and review common terms in the title, abstract, author-supplied keywords that are relevant to your research question. Start testing in your primary database using the advanced search filter, limiting the search to the title and abstract fields. You can create a free account on database platforms to save your searches. Keep a running document open to record the terms you test and build your strategy. After testing, record the search strategy in your protocol.

Controlled Vocabularies

Controlled vocabularies assign a subject heading to index different concepts to the same term. Examples of controlled vocabularies the Library of Congress Subject Headings (as seen in the Search@UW online catalog) and MeSH (Medical Subject Headings). Individual databases, like PsycInfo and CINAHL, also have their own subject headings listed in a Thesaurus or Index. Search for the "representative articles" in a database the controlled vocabulary used to index the articles.

Example: To find the evidence for the effectiveness of group interventions for a specific population, you can use keywords like groups OR "group work." These terms may be different than the controlled vocabulary terms, as seen below.

Library of Congress: "Social group work"

MeSH: "Self-help groups"

PsycInfo: "Group Counseling", "Group intervention", "Social Group Work", "Support groups"

Database syntax

Using database syntax can help you refine your search. For example using "double quotations" will narrow searches by searching only for that specific phrase rather than each individual term. Using truncation (*) or wildcard (?) can expand your search by expanding the scope of a single term. Note the wildcard (?) symbol doesn't work in Search@UW.

Symbol	Use	Function	Example
"..."	Double quotation marks	Searches exact phrase	"prison release"
*	truncation	Adds none or more characters	sentence* searches sentence, sentenced, sentences, sentencing, etc

Different database platforms (i.e. EBSCO, ProQuest) may use different syntax. Review a more complete list of database syntax.

Search Translation Guide
Guide for translating syntax and search strategies across databases

Boolean Operators

Boolean Operators are commands that indicate the relationship between one or more terms, with the most common being AND, OR, and NOT. Using AND between the terms queries results that include both terms and using OR between terms will include either term. See illustrated venn diagrams below.

Grey Literature

Grey literature are information sources that have not been published through the academic peer review process. It's important to identify these works to limit publication bias* and include the most up-to-date information in your review. These information sources include:

Conference proceedings
Theses and dissertations
Preprints
Working papers and reports created by government agencies, institutions, think tanks, advocacy groups and non-profit or professional organizations
Government documents
Patents
Clinical guidelines and technical reports

There is no one place to search for all grey literature, so it's best to consult with a subject expert on where to search.

Where to look for grey literature

Preprint servers: arXiv, socArxiv, RePEc, OSF
Institutional and open repositories: ROAD, Digital Commons Network
Government agency, institution, non-profit or professional organization individual websites
Policy Commons
Identify researchers in the field and look at their websites, scholar profiles, ResearchGate, LinkedIn, Bluesky accounts for new research

Directory of Open Access Preprint Repositories
This directory provides a list of preprint repositories that are available to the research community. It helps researchers find the most appropriate platform for them, enabling them to browse through existing repositories by discipline, location, language, functionalities, and other facets.
ASAPBio
Directory preprint servers across disciplines. Includes policies and practices across platforms for each server.
ROAD Directory of Open Access Scholarly Resources
There are 5 types of multidisciplinary, open access resources in ROAD: there are mostly journals, but also monographic series, scholarly blogs, academic repositories and conferences proceedings.As the ISSN network covers the whole world and identifies any type of continuous resources, the geographic and linguistic coverages of ROAD aim to be comprehensive.
Directory of Open Access Repositories
OpenDOAR is the quality-assured, global Directory of Open Access Repositories. You can search and browse through thousands of registered repositories based on a range of features, such as location, software or type of material held.
Registry of Research Data Repositories
Re3data is a global registry of research data repositories that covers research data repositories from different academic disciplines. It includes repositories that enable permanent storage of and access to data sets to researchers, funding bodies, publishers, and scholarly institutions. re3data promotes a culture of sharing, increased access and better visibility of research data.
Preprint repository search syntax table
Table of search syntax for select preprint repositories and aggregators

AACODS checklist
The AACODS checklist is designed to enable evaluation and critical appraisal of grey
literature.Unpublished studies, RCTs, and other grey literature should be appraised using the same tools as their published counterparts.

Other search methods

To conduct an exhaustive review, your search should include research that may not be indexed or published in a peer-reviewed journal. In addition to database searching, consider also searching:

table of contents of relevant journals and special issues (manual search)
forward/backward citation searching
individual organization, agency, or institute websites
discipline specific preprint servers and open access repositories
network announcements to relevant research communities (listservs, social media)
personal correspondence to researchers

In your protocol, indicate any specific journal titles, conferences, or organizations who disseminate research relevant to your topic, that you plan on manually searching.