Use Boolean to focus or expand a search
What are Boolean Operators?
Boolean operators, also called connectors, are represented by the terms AND, OR, NOT. These terms can be placed in between keywords or/and Subject Headings to focus or limit a search in FindIt@Flinders, library research databases and Google.
There are three Boolean operators: AND, OR, and NOT. They are used to link your keywords together in different ways to get the best search results possible.
Things to consider when using Boolean Operators
- Some databases automatically apply an AND or OR operator to keywords unless you specify otherwise.
- Different databases handle the operators differently so check the database help.
- Unless you are conducting a highly structured search such as a Systematic Review it is usually best to keep your search strategies simple. When you add too many operators your search structure can cause unintended results.
- When using boolean operators you can create a search strategy that is ambiguous because it isn't clear if the search requires the OR operators to be dealt with before the AND operators. Use Nesting or parentheses to make this more specific.
Want to know more?
Watch the video below for an overview of how to apply these operators in a search.
What is Nesting
Nesting is the technique of using parentheses () in your search statement to designate the parts of the query that should be dealt with first when combining AND and OR operators in a more complex search string.
For example, grammar AND (adolescents OR teenagers). In this search the OR operation is nested and will be performed first. Then the AND operation will be performed. This search will retrieve items on grammar and adolescents as well as items on grammar and teenagers.
For a more complex example, (facebook OR "social media" OR texting) AND (adolescents OR teenagers). The OR operations inside both sets of parentheses will be performed first, and then the resulting sets will be combined using the AND operator. Nesting synonyms in this way can broaden your search.
Without parentheses the example, facebook OR "social media" AND adolescents OR teenagers This search will perform the OR and AND operations in the sequence that they are typed and retrieve irrelevant results that are just about teenagers, not just those relating to social media.
Things to consider when using Nesting or Parentheses
- Sometimes using the advanced search option of library research database allows options to set up a search in a logical fashion without parentheses.
What are Proximity Operators?
Proximity Operators allow you to determine how closely you want a keyword or search term to be to another keyword in your search results. For example,
grammar NEAR teenagers - grammar must be within a paragraph of teenagers in the documents you retrieve (depending on the database).
grammar /5 teenagers - teenagers must be within 5 words of the word grammar.
Some databases allow you to be specific about word order for example,
grammar pre/5 teenagers - grammar must be within five words before the keyword teenagers.
Things to consider when using Proximity Operators
- Not all databases allow them so check their help pages to be sure.
- Keep it simple! It is possible to create over complicated searches when using too many search strategies in one search.