Research in the Disciplines Supplementary Research Guide 01:355:201

Why use Boolean operators?

To focus a search, particularly when your topic contains multiple search terms.
To connect various pieces of information to find exactly what you're looking for.

Use AND in a search to:

• narrows your results
• tells the database that ALL search terms must be present in the resulting records
• example: cloning AND humans AND ethics

The result set is represented by the space where the two circles intersect in the middle of the Venn diagram below. Joining the two terms with AND will produce a smaller result set where each individual result must include both moths and butterflies

moths AND butterflies

Use OR in a search to:

• connect two or more similar concepts (synonyms)
• broaden your results, telling the database that ANY of your search terms can be present in the resulting records
• example: cloning OR genetics OR reproduction

The complete two circles represent the result set for this search. It is a big set because both words are valid using the OR operator. Any individual result can include either moth, butterfly, or both.

moths OR butterflies

Use NOT in a search to:

• excludes words from your search
• narrows your search, telling the database to ignore concepts that may be implied by your search terms
• example:  cloning NOT sheep

moths NOT butterflies

Sample Boolean Search

Narow focus: financial aid AND college

Narrower focus: financial aid AND college AND application

Combining Boolean operators: (Financial aid OR scholarships) AND (college OR university) AND application

Exclusion: college AND financial aid NOT scholarships

• Use " " to search for phrases
• Use * to include different possible word endings (assess, assessment, assessments)
• Use AND to narrow the search (must include both middle school and math)
• Use OR to widen the search (results will include both assessment and evaluation)