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Capstone and PICO (T) Project Toolkit: 2. Boolean Logic

Guide to locating research for evidence synthesis projects and assignments.

Boolean searching: handwashing and hospital acquired infection

Boolean logic uses the operators AND, OR, and NOT to connect search terms when using catalogs, databases, or a web search tool.

  • A simple search on: handwashing retrieves article citations containing that term.
  • A simple search on: handwashing AND hospital acquired infection retrieves citations containing BOTH terms.

 

Example research question:
Does handwashing among healthcare workers reduce hospital acquired infection?  

The main concepts are...

The Problem: hospital acquired infection

The Intervention: handwashing

Combine the two terms for a preliminary search.

 

BOOLEAN
OPERATOR    		 SEARCH STATEMENT RETRIEVES  

AND

hospital acquired infection

AND

handwashing

Retrieves citations with BOTH terms present
OR

hospital acquired infection
OR
cross infection
OR
nosocomial infection
 

Retrieves citations with EITHER/ANY of the terms present

 

(OR is used to string synonyms together; remember, OR retrieves MORE!)
AND, OR 

(cross infection
OR
nosocomial infection
OR
hospital acquired infection)

AND

handwashing
 

 

 Search sets may be combined. This search locates citations with the word handwashing AND (ANY one of the terms combined with OR)
AND, OR

(cross infection
OR
nosocomial infection
OR
hospital acquired infection)

AND

handwashing

AND

Publication type: randomized controlled trial

Retrieves citations with the word handwashing AND (ANY one of the terms combined with OR) AND limited to articles with the Publication type: randomized controlled trial.

(This is one example of using database Limits.)
NOT

handwashing

NOT

masks

Retrieves citations with the term handwashing, but omits records with the term masks

(Caution: the NOT operator should be used sparingly and carefully as it may omit citations relevant to a search.  

For example, an article about handwashing that includes the word masks might be relevant to a search on handwashing.)

 

A SAMPLE RESULT FROM Medline/Pubmed:

Boolean: Driving and Mobile Phone

Boolean logic uses the operators AND, OR, and NOT to connect search terms when using catalogs, databases, or web searching. 

  • A simple search on driving retrieves article citations containing that term.
  • A simple search on driving AND mobile phone retrieves citations containing BOTH terms.
  • A search combining terms with AND and synonyms with OR is shown below, to answer the research question:

Is there evidence that the use of a mobile phone while driving increases the incidence of accidents?.

BOOLEAN
OPERATOR    		 SEARCH STATEMENT RETRIEVES  

AND

driving

AND

mobile phone

AND narrows your search results to citations with BOTH terms present. 
OR

mobile phone
OR
cell phone
OR
text messaging
 

OR broadens your results to include citations with EITHER/ANY of the terms present.

OR is used to string synonyms together.

Remember, OR retrieves MORE!
AND, OR 

driving

AND

(mobile phone
OR
cell phone
OR
text messaging)

 

This search locates citations with the word driving AND (ANY one of the terms combined with OR).

The area where all 3 circles overlap represents search results with all criteria.

 

  
NOT

driving

NOT

cycling

Retrieves citations with the term driving, but omits records with the term cycling

(Caution: the NOT operator should be used sparingly and carefully as it may omit citations relevant to a search.  For example, an article about cycling might also be relevant to driving.)

 

Youtube Video: the "Bike Helmet Search," Using Boolean Operators (2 min, 38 sec)

YouTube: Falls AND Exercise (2 min.)


Do Exercise Programs Reduce the Incidence of Accidental Falls in the Aged Population?

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