Boolean operators are connecting words (OR, AND, and NOT) that link two or more keywords or phrases in your search. As their name implies, Booleans act like operators (=, +, -) in a database, telling the search tool to look for your keywords in a specific way.
The first operator, OR, is like telling the database "I want Coke but Pepsi is fine, too."
OR will find records containing one or both of your search terms together. For example, the search terms visualized below (Rural America OR opioid addiction) will retrieve articles about either rural America, opioid addiction, or both. With this basic search, you might get a lot of results about rural America that have nothing to do with opioid addiction and vice versa.
In contrast, using AND as your Boolean operator is like telling your waiter at the restaurant "I want diet Cherry Coke, and I'm not willing to settle for normal Cherry Coke or plain diet Coke. It has to be specifically Cherry AND diet"
AND specifies that you only want to see results containing all your keywords together. In the example below, (Rural America AND opioid addiction), you will only find articles about opioid addiction in rural America.
Finally, NOT is a search term you won't have to use very often. To keep using our drinks metaphor, NOT is like asking your waiter for a diet Coke and stating that you will NOT take diet Pepsi as a replacement.
NOT will find records containing the first term/phrase but not the keyword(s) following the NOT. This is most useful when the term you're searching for has a second meaning or connotation that is widely different from the one you want. In the example below, searching for opioid addiction NOT rural America will only yield results about opioid addiction, and none that reference rural America.*
*Note: Using NOT can be temperamental. In the case above, there may be terms other than "rural" that people use to refer to smaller, agriculturally-minded communities. Because of this, you may still get results about rural America even after using NOT.
Let's say you want to find information about addicts in America. Using the Boolean AND we covered above, you might put together this simple search:
addict AND America
However, there is a way to make this search a little more effective: truncation. Truncation works by adding a symbol (*) to the end of a word or word root. The symbol tells a database to look the word you have listed with any ending that follows the placement of your asterisk. For example:
addict* AND America
This search would include additional words such as: addicts, addiction, addictive, and others. Using truncation can help you get all of these words out of your search results without having to search for them individually.
BEWARE! Do NOT truncate too far back. If you were to search for add* you would retrieve results about addition, additives, and all sorts of other topics unrelated to your research.
How do you put all of these search techniques together? Why not make a nest?
Nested searches are so named because of their "nests" made up of parentheses. These nests are used to separate different topics or pieces of your search from one another. In essence, they work the same way that parentheses work in Mathematics: the Boolean operators within the parentheses are applied to your search first, and then they are searched with any terms or phrases outside of the parentheses. For example:
addict* AND (America OR "United States" OR USA)
Similar to truncation, nesting can help you search for alternate versions of the same term. However, unlike truncation, nesting can be used to search for wildly different spellings as well. This can be incredibly useful when doing research on young people, for example, where you might want to use the terms: adolescent, teenager, children, young adults, or youths interchangeably. Adding a nest into your search will allow you to search for all of those terms at the same time:
addict* AND (America OR "United States" OR USA) AND (adolescents OR teenager OR children OR young adults OR youths)
The key to a good nested search is to get creative! Try different terms, add more or take some away from you (ORs) and most importantly, keep a record of what combination of terms works the best. You can try the exact same search in other databases as well, to try and find alternate resources you can add to your lit review.
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