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Research Help: Boolean search

What is Boolean searching?

Boolean operators are words that define the relationship between keywords and/or phrases. They can be used to narrow down a search.

Most search engines and databases support Boolean searching.

Using Boolean operators

You can use the word ‘AND’ to link ideas together.
For example: to find information on how mental health might affect incidences
of juvenile delinquency try searching for:

Boolean searching using AND

You can expand your search to include words with the same or similar meanings
by using ‘OR’.
For example: to find information about grieving people you might try:

Boolean searching using OR

You can exclude ideas or words from your search using NOT. This is useful if one
or more of your search words are also used in a completely different context.
For example: If you had searched for play theory but had lots of results about
“foul play” theories, you could search again trying:

Boolean searching using NOT

Parentheses (brackets)
Remember BODMAS from primary school? The same thing works for boolean
searching. You can use parenthesis to build searches. The computer will look at
what is in the brackets first, and then deal with what is outside the brackets. This
allows you to use the OR term inside the brackets to group a single idea made
up or two or more words that mean the same thing, and then link the ideas by
using the AND term between the brackets.

For example: if you are looking for information on how divorce affects children
you could try:
                      (divorce OR separation) AND (child OR children) 

This will allow you to search for 2 different concepts (divorce, and the children
involved) at the same time, but without limiting yourself to particular keywords
when the words themselves don’t matter as much as the concepts.


The referencing in this guide is based on the APA referencing system, as outlined in: American Psychological Association. (2010). Concise rules of APA style (6th ed.). Washington: American Psychological Association.

Advanced Search Techniques Part 1: Boolean Searching

Boolean Searching Basics from University of Regina