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Sherratt Library

Searching Strategies: Keywords, Boolean Operators and Truncation

Databases have several features that will allow you to build searches that will focus your search to relevant information. These features include keyword and subject searching, Boolean operators, truncation, phrase searching, search limiting, and nesting. Understanding these techniques will allow you to search more efficiently and effectively.

Keyword Searching

Computers index "significant" words in databases in the title, summary, subject or even the text fields of a record or article. These words are then searchable. When you type these words into the database search window, this is called keyword searching.

Keyword searches are best used when you're searching for new terms, distinctive words, jargon or slang. When keyword searching, databases do not index certain commonly used words and parts of speech, called stop words, such as articles, pronouns and prepositions. Examples of stop words in databases are a, an, about, after, all, also, and, any, are, as, at, based, because, been, between, and so on.

The disadvantage of keyword searching is that you only find records that contain the terms you type. You can miss synonyms of the terms you use. A keyword search may also find many more records than you want.

Phrase Searching

Phrase searching is a way to retrieve records containing specific phrases. To search for a specific phrase, most databases require quotation marks around the phrase. A phrase search will then locate only records containing the words in the particular order in which they appear.

Examples of phrase searching:

Subject Searching

A subject search will only search the subject field of database records. Records in databases are assigned subject headings from a thesaurus for that database. When a thesaurus is available, it will provide you with a list of subject terms and suggested terms for narrower, broader or related topics.

For example, if you were doing research on how driving is affected by the use of cell phones, you might search for cell phones and find this record:

Title: Study: Cell Phones Cause 'Blindness' in Drivers.
Subject(s): cellular telephones; traffic safety
Source: Safety & Health, Mar2003, Vol. 167 Issue 3, p14, 1/4p
Abstract: Discusses findings of the study, titled 'Cell phone use can lead to inattention blindness behind the wheel,' conducted by researchers at the University of Utah in Salt Lake. Effects of inattention blindness or the inability to recognize objects encountered along the road.

You'll find that the words cellphone, cell-phone, cell phone, cellular phones, and cellular telephones, are all words used to describe this device.

A look at the subject field in this record indicates that the subject is cellular telephones. If you then use this subject for further searching you will find articles that are the most relevant to your topic.

Advantage: Since subject searching is based on words in the thesaurus for the database, you will retrieve only articles assigned that subject, and your results will be very reliable.

Disadvantage: Subject terms may vary from one database to another.

Boolean Operators: AND - OR - NOT

Boolean operators, named after British mathematician George Boole (1815-1864), can be placed between your search terms to narrow or expand a search, or to exclude search terms.

In these examples of how to use Boolean operators, Venn diagrams are helpful to visually illustrate how these operators can be used:

Example 1:  Your topic is "how exercise and health are related."

AND

exercise and health and age

will retrieve even fewer records than Example 1.

Example 2:  You are looking for "information on salary."

OR

Example 3:  Your topic is about bears, but not grizzly bears.

NOT

Truncation

By adding a symbol, sometimes called a wildcard symbol, to the end of a word, truncation allows you to search the "root" of a word to find all its different endings. The most common truncation symbol is the asterisk asterisk. However, some databases use different symbols, so check online help to find the correct symbol.

Example:  You are looking for information "the banking industry."

bank* finds: bank banks banking bankers bankruptcy

Limiters

Many databases and search engines allow you to limit searches to specific criteria such as format, language, publication date, and periodical title.

For example, the Academic Search Premier database provides several useful limiters,

Limiting will NARROW your results. Limiters let you narrow the focus of your search so that the information retrieved from the databases you search is limited according to what you select.

Nesting

Many databases allow for very complex searching. For example, nesting allows you to place parentheses around strings of searches using Boolean operators.

For example, if you wanted articles about the geology in Utah, Colorado, or Nevada, a nested search using parentheses and Boolean operators, you could use this search . . .

geolog* and (utah or colorado or nevada)

Other examplesof nesting searching: