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Research Help

Boolean Operators

The Boolean Operators AND, OR, and NOT are often used to combine or exclude keywords when conducting searches in research databases. These operators can focus or maximize your searches and yield more productive results. Before using these operators, it is important to know how they work.

Boolean Searching

Retrieves items that contain both terms

Retrieves items that contain either term

Retrieves items that contain only one item

Decreases the number of results

Increases the number of results

Decreases the number of results

 

 Remember that the operators AND and NOT limit your search, while the operator OR expands it. Use the following strategies during your database research:

  • If you are retrieving too many results, try adding another search term related to your topic with the operator AND.
  • If you are retrieving too many results on an unrelated topic, try eliminating a word from the unrelated topic with the operator NOT.
  • If you are retrieving too few results, try adding another search term related to your topic (or a synonym related to your first search term) with the operator OR.

Examples:

wasps AND hornets

Boolean operator AND asks the database to bring back items that mention both wasps AND hornets.

ocean OR sea

Boolean operator OR asks the database to bring back items that mention the ocean, the sea, and items that mention both the ocean AND sea.

cats NOT broadway

Boolean operator NOT asks the databases to bring back items that mention cats but do not mention Broadway.

Truncation

Truncation allows you to search a “root” word and all its various endings by adding an asterisk (Shift + 8 on your keyboard) to the end of a word. For example, typing in bank* will retrieve results that contain these words: bank, banks, banking, bankers, bankruptcy. Using truncation increases your search results, so this method is best used if you are yielding too few results on your topic.

Quotations

Quotation marks keep words together and ask the computer to search for the phrase instead of each individual word. Think of the quotations as glue that stick the words together. For example, if you search "mental health" in a database, you will retrieve items that contain that phrase instead of items that contain the word mental or the word health. Quotations are especially helpful if you are searching for a specific work like a poem, short story, or book. Placing quotations around titles or short phrases will yield precise results.