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Literature Searching: Combining Search Terms

Combining your search terms

The next step is to combine your search terms.

There are 3 connectors (known as Boolean operators) that can be used to combine your terms:

  • AND
  • OR
  • NOT

AND

Use AND to find references containing all of your terms when you are combining different concepts.

This will narrow or focus your search, for example:

fish AND chips

will find references containing both the word fish AND the word chips

OR

Use OR to find either of your terms when you are combining similar concepts such as alternative terms and synonyms and alternative spellings.

This will broaden your search and find more references, for example:

fish OR chips

will find references containing the word fish OR references containing the word chips.

NOT

Use NOT if you want to exclude an unwanted term from your search.

This will narrow or focus your search, for example:

fish NOT chips

will find references containing the word fish but NOT the word chips.

Hint: NOT should be used with caution to avoid excluding potentially relevant references.

Combining our example search terms

How to combine terms:

In most databases, the AND operator is given priority over the OR operator, therefore in order to tell the database how to combine our terms, we need to enclose the terms that we want it to combine with OR in brackets:

(older OR elderly OR aged) AND pilates AND (falls OR balance)

How not to combine terms!:

In the above example, if we fail to use brackets, the database will start by searching: older AND elderly OR aged, which would find references containing both the words older and elderly together which is not what we want it to find.