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Professional MPA

Connecting Keywords: Boolean Operators

Once you have identified the keywords and phrases that describe your topic, the next step is to connect them in a logical way that the database will understand - this is accomplished with the use of Boolean operators: AND, OR, NOT. Boolean operators connect your search words together to either narrow or broaden your set of search results

Databases and search engines such as Google make use of Boolean logic. Understanding how databases interpret your keywords will allow you to execute more specific searches, thereby saving you time while retrieving more relevant results. Boolean operators allow you to focus a search, particularly when your topic contains multiple search terms or concepts.

In many databases the Boolean operators are built into the search boxes. A database's Help pages will indicate how to construct Boolean searches and which wildcards the database supports.

Venn diagrams are helpful to visually illustrate how these operators can be used.

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: women AND income

  • 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: < university students test anxiety > is translated to:  university 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:  "university 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: teenagers OR youth 

example of using OR between two keywords


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
  • use NOT sparingly, if at all, because you could end up excluding useful search results (e.g. articles or books that discuss both concepts)
  • example: exercise NOT fitness