How to Narrow or Broaden A Topic

Boolean Operators: or, and, not

Boolean operators are words (connectors) placed between search terms to narrow or expand a search.

It is helpful to diagram the effects of these operators:

	And retrieves all records that contain all the search terms. It narrows the search.
	Or retrieves all records that contain any of the search terms. It expands the search
	Not eliminates a search term or group of search terms. It narrows or limits the search.

When you enter two search terms without using a connector, be aware that the databases may be set up to do one of three things:

1. Search for records containing all terms.   This is called "implied AND."
2. Search for items containing any of the terms. This is called "implied OR" and is often employed by Web search engines. This can display thousands of records.
3. Search for a phrase i.e. 2 or more words that are adjacent and in the exact order.

Keep in mind that the connectors AND and NOT generally limit your search (decreases the number of hits) and the connector OR expands it (increases the number of hits).

Search strategies:

• If you are retrieving too many records on your topic, add another term with the connector AND.
• If you are retrieving too many records on an unrelated topic, eliminate a word with the connector NOT
• If you are retrieving too few records on your topic, add another search term with the connector OR.

Truncation and Wildcards

Most electronic databases allow for a symbol to be used at the end of a word to retrieve variant endings of that word. This is known as truncation.

Truncation allows you to search the "root" form of a word with all its different endings.

Using truncation will broaden your search. For example,

bank* will retrieve: banks, banking, bankers, bankruptcy

Databases and Web search engines use different symbols to truncate. Check to find the correct truncation symbol.

In GEAC Advance and InfoTrac, the "*" is used as a truncation symbol.

Be careful using truncation!

Truncating after too few letters will retrieve terms that are not relevant. For example:

cat* will also retrieve cataclysm, catacomb, catalepsy, catalog, etc.

It's best to use the boolean operator "or" in these instances (cat or cats).

Wild Cards

Some databases allow for wild cards to be embedded within a word to replace a single character. For instance, in InfoTrac, you can also use ? within a word to replace a character. For example:

comp???tion finds composition, competition, computation, etc.

Studying at home and need help? Ask reference questions via email.

Campus Home Library Home Research Ask a Librarian
28 September 2000 Library Webmaster
http://library.csun.edu/mwoodley/Boolean2.html

Questions about this page, contact: Instructional Web Pages Committee