Systematic Reviews, Scoping Reviews & Other Evidence Synthesis Projects

Advanced searching strategies are important for any kind of evidence synthesis project you might do because it is important to know you are finding all of the literature that is relevant to your topic. 

These searching strategies and tricks can help you no matter what kind of review you are doing. 

Remember that if you need help forming a search strategy or finding materials, your Boxer Library librarians are here to help.

Boolean operators are specific words that you combine with your keywords to either limit or expand your search. The three basic boolean operators are AND, OR, and NOT. The following graphic illustrates the use of Boolean logic. You can think of A and B as representing two keywords.

AND

Using AND to combine your keywords will limit your results. If you do a search for monkeypox AND vaccine you will be finding only the articles that mention BOTH monkeypox and vaccines. AND is best used to combine the different concepts included in your research question.

OR

Using OR to combine your keywords will expand your results. If you do a search for moneypox OR vaccine you will be finding articles that mention monkeypox or articles that mention vaccines. OR is best used to combine different keywords/synonyms for the same concept.

NOT

Using NOT will tell the database to not return results with a specified keyword. If you do a search for monkeypox NOT vaccine you will be finding articles that mention monkeypox but not articles that also mention vaccines.

Image: Jakub T. Jankiewicz, CC BY-SA 4.0, via Wikimedia Commons

Controlled vocabularies are standardized terms that databases use to consistently describe content. Research databases use controlled vocabularies to assign standardized terms to the indexed articles and other resources in them. This is useful because often times there are multiple ways to refer to the same concept (e.g. heart attack and myocardial infarction). Controlled vocabulary ensures that if you search for heart attack in a database, you will also find results that refer to that concept as myocardial infarction.

Each database may name their controlled vocabulary differently.

It is highly recommended to use BOTH keywords AND controlled vocabulary together when searching. Controlled vocabularies are assigned to articles in a database during a process called indexing. The indexing process isn’t perfect and takes time. Brand new articles may not have controlled vocabulary assigned to them yet. Indexing also is a subjective process so using keywords makes sure that you find any articles that may be appropriate despite missing the controlled vocabulary terms.

In many databases, if you search for heart attack it will automatically put an AND in between the words (heart AND attack) this will return results that are about heart attacks but theoretically, it could also return results that has the word "heart" somewhere in it and "attack" somewhere in it, without it really being about heart attacks. 

To ensure that the database searches heart attack as a phrase, with the two words together, put quotations around it (e.g. "heart attack").

Wildcards, truncation and proximity operators all allow you to create a more expansive and targeted search.