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Gerstein Science Information Centre

Searching the Literature: A Guide to Comprehensive Searching in the Health Sciences

Students and researchers in the health sciences are often required to conduct comprehensive searches of the literature. Follow the steps in this guide to learn how this process works.

Using AND/OR (aka Boolean Operators) to Construct Search Strategy

We use Boolean Operators (OR, AND) to combine search terms in library databases.

Boolean Operators:

  • are required to turn a research question into a query the database can understand
  • make searching more efficient
  • enable searchers to combine dozens of queries into one

Let's use the below example question to see how Boolean Operators are applied. 

Example Question: what is known about substance abuse in teenagers? 

 

REVIEW STEPS
  1. identify the core concepts in the question (teenagers, substance abuse)
  2. determine synonyms for each concept
  3. combine the terms logically

Search sets are combined logically using AND or OR.

  • OR: combines terms for the same concept e.g. teenagers OR adolescents OR youth
     
  • AND: combines different concepts e.g. teenagers AND substance abuse

Note: You can also use brackets to group concepts and force an order of operations.  

Example Query: (teenagers OR adolescents OR youth) AND (substance abuse OR addiction OR alcohol abuse) 

 

This forms the basic skeleton of your search strategy. It's often helpful to express your skeleton strategy as a venn diagram or as a chart (see below). 

Visualize your Search Strategy - 2 Options

Option 1: Venn Diagram

You might find drawing a venn diagram helpful when constructing your search strategy. Underline your major concept in each circle, list all your synonyms below each each concept and then identify the overlap where you will find the most relevant literature. 

Venn diagram with relevant records at the centre. Each circle has a concept (RCTs concept; children concept; substance abuse concept) and the intersecting sections show how the two concepts interact.

 

Image from Cochrane Handbook Section 6.4.a: Combining concepts as search sets

Option 2: Chart

You may also choose to organize your thoughts into a chart, as shown below.

Concepts: Substance Abuse | Teenagers | Randomized Controlled Trials

Substance Abuse

AND

Teenagers

 

 

 

 

 

 

  AND

Randomized Controlled
Trials

OR

OR

OR

Addiction

Youth

RCT

OR

OR

OR

Alcohol Abuse

Young Adult

Controlled Clinical
Trial

OR

OR

OR

Addictive Behavior

Adolescent

Placebo

OR

OR

OR

Drug abuse

Highschool 
students

Blinded

OR

 

 

Addict

 

 

OR

 

 

Narcotics

 

 

 

 Search Strategies Must Always be Tailored to the Database!

  • vendor/interface differences (ex. OVID vs. EBSCO vs ProQuest)
  • subject headings versus keyword-only (ex. MEDLINE vs. SCOPUS)
  • peer-reviewed content only (MEDLINE:yes, CINAHL:no)
  • different controlled vocabularies (ex. Medline - MeSH vs. Embase - EMTREE vs. CINAHL - Headings) 

This work is openly licensed via CC BY-NC-SA 4.0. For information on this guide contact Erica Nekolaichuk, Faculty Liaison & Instruction Librarian at the Gerstein Science Information Centre.