LibGuides: Research Process: A Step-by-Step Guide: 2d. Search Strategies

What are Boolean Operators?

We use the words AND, OR, and NOT everyday in conversation without even thinking about them. But when we use these common words in a search engine (like Google), the library catalogue, or a database they become powerful search tools.

This guide will introduce you to the basics of using Boolean Operators, so that you can get better results when searching for books and articles.

Operator	Examples	Results
AND	business AND ethics cooking AND Spain	Retrieves records that contain ALL of the search terms.
OR	hotels OR motels www OR world wide web theater OR theatre	Retrieves records that contain ANY of the search terms, but does not necessarily include all of them.
NOT	java NOT coffee Clinton NOT (William OR Bill)	Excludes records containing the second search term.

What To Look For

Boolean operators form the basis of mathematical sets and database logic.

They connect your seach words together to either narrow or broaden your set of results.
The three basic boolean operators are: AND, OR, and NOT.

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.
Example:
second creation (title) AND wilmut and campbell (author) AND 2000 (year)

Using AND

Use AND in a search to:

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

The purple triangle in the middle of the Venn diagram below represents the result set for this search. It is a small set using AND, the combination of all three search words.

Be aware: In many, but not all, databases, the AND is implied.

For example, Google automatically puts an AND in between your search terms.
Though all your search terms are included in the results, they may not be connected together in the way you want.
For example, this search: college students test anxiety is translated to: college AND students AND test AND anxiety. The words may appear individually throughout the resulting records.
You can search using phrases to make your results more specific.
For example: "college students" AND "test anxiety". This way, the phrases show up in the results as you expect them to be.

Using OR

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

All three circles represent the result set for this search. It is a big set because any of those words are valid using the OR operator.

Using NOT

Use NOT in a search to:

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

Tip!

Too much info? Not finding enough?
Narrower or broader your search.
How? Keywords will vary your results.

Use Help
Each search tool has a Help file which will show you how to get the best results.

Google Search Strategies

If your initial search query does not produce the desired results, try these search strategies.

Search Strategies	Examples
Queries are not case sensitive.	Barack Obama and barack obama will retrieve the same results.
Results will typically include each word or punctuation mark included in the search query. Some stop words or exceptions apply.
Keep search queries simple and descriptive and use as few terms as possible. Avoid natural language queries as they can limit your results.	Use colorado statehood instead of when did colorado first become a state.
Google automatically truncates search terms. To prevent automatic truncation, use a + sign in front of each term.	A query on child retrives results with 'children" and "childcare".
Use double quotations marks ("") to search terms as a phrase and narrow your results. Google will only retrieve results that have those exact terms in the exact order typed.	A query on Barack Hussein Obama II will retrieve only those sites that refer to Obama by his full name. Sites that refer to him as simply 'Barack Obama' may be overlooked.
Use the site: feature to limit your results to a specific website or class of websites.	The query cloning site:online.wsj.com will only retrieve articles about cloning from the online version of the Wall Street Journal. A query on cloning site:.gov will only retrieve results within the government domain.
To allow for either of several words to appear in your results, use the OR operator. The operator must be in all caps.	A query on hotel OR lodging OR inn directories will retrieve any or all of the types of directories mentioned.