Guide to Searching

More details and examples of Boolean terms are given below.

A few tips to start:

• The operators must be written in ALL CAPS (there are exceptions, but this is good practice and helps you keep track of your search terms)
• The default in most databases is to combine the terms with the AND operator:

Example:  cognitive behavioral therapy becomes (cognitive AND behavioral AND therapy)

• Use a NOT operator to exclude terms from your search (see NOT example below)
• Databases generally have an order in which they process Boolean terms, but that order may differ between databases; Use parentheses (nesting) to change the processing order. See the section on nesting below. 
• Use quotation marks for phrases (unless you are using a database with automatic term mapping - like PubMed)

Watch this short 4-minute video on Boolean Searching: 

Use AND to connect two or more concepts

• Narrows your search
• Retrieve less results
• Results will contain both concepts

Example :
classroom management AND student behavior

Some databases use "+" instead of (or in addition to) AND.

Use OR to connect two or more similar concepts (synonyms)

• Broadens your search
• Retrieve more results
• Not all results will contain both concepts

Example :
assessments OR evaluations

Use NOT to exclude concepts from your search.

• Narrows your search
• Tells the database to ignore results with one concept - even if those results contain other concepts used the search

Example :
osteoporosis NOT arthritis

Some databases use the -  symbol or AND NOT instead of NOT.

Here are a number of examples in combining three concepts with Boolean terms.

• engineer AND Latino AND arthritis = 7 (only articles that include all three concepts)
• engineer OR Latino OR arthritis = 1+2+3+4+5+6+7 (any article that contains any of these concepts)
• engineer AND Latino = 5+7
• (engineer AND Latino) NOT arthritis = 5
• Latino OR engineer = 1+5+2+4+6+7
• (engineer OR Latino) NOT arthritis = 1+5+2
• engineer OR (Latino NOT arthritis) = 1+5+2+4
• Latino NOT arthritis = 5+2

Nesting, or mixing the Boolean operators, is a way to combine several search statements into one comprehensive search statement.

Use parentheses ( ) to separate keywords when you are using more than one operator and three or more keywords. The order in which the operations (AND, OR , NOT) are processed can vary between systems. Searches within parentheses are performed first and operations proceed from left to right.

Example:  diet therapy AND (bulimia OR anorexia) will retrieve records containing the two concepts, Bulimia + Diet Therapy, or the two concepts, Anorexia + Diet Therapy, or records that contain all three concepts, Bulimia + Diet Therapy + Anorexia. 

If you don't put in the parentheses, the search statement is processed strictly from left to right, so that the AND is done first. This search strategy will retrieve records containing both of the concepts, Diet Therapy + Bulimia, or any records with the concept Anorexia.

In addition to Boolean terms, search strategies can include other options including Proximity Indicators (e.g., NEAR, ADJ, and PRE), truncation or Wildcard symbols (?, and *), the hyphen (-), and specialized options (e.g. SAME or EXACT). See the Additional Search Options tab for more details on using these search strategies.