Boolean Searching: From Finding Health Information: Home
A supplement to "A Path Through the Maze," this tutorial from the "Finding Health Information" series talks more in-depth about Boolean search techniques.
Boolean (boo'-le-an) searching helps you find less (narrows) or find more (broadens) results when you search in many databases and Web search engines. Boolean searching depends on the use of three terms: AND, OR, and NOT. Enter these terms in ALL CAPS because many search engines are case sensitive for these terms.
By using the word AND in your search, you can tell the database to only bring you back items in which both search terms occur.
For example, if Cheryl types the phrase "exercise therapy for diabetes" in HealthSource Nursing/Academic Edition, she will get NO articles! But, if she enters "exercise therapy AND diabetes" she gets more than 40 articles. From there she can narrow her search or just scan through her results.
By using the term OR, you can retrieve items that contain any of the search words. This keeps you from having to run your search multiple times for each of the words.
For instance, Cheryl's search for "exercise therapy AND diabetes" may not find articles that deal with exercise training for diabetes, a very similar topic. She could miss the perfect article for her research!
But, if she uses the search "(exercise therapy OR exercise training) AND diabetes" she will get an additional 15 articles that are related to her research. From there she can narrow her search or just scan through her results.
By using the word NOT in your search, you tell the searching tool that you want information on one topic, but not on a related one. Consider carefully before using NOT because you may miss articles important to your topic.
For example, Cheryl would use NOT if she wanted to eliminate articles referring to hypertension. She would use the search "(exercise therapy OR exercise training) AND (diabetes NOT hypertension)".