What is a Boolean Search?
A handy strategy to know when searching a periodical article database or the entire Internet using a search engine such as Yahoo or Google is what is called Boolean searching. By using this strategy you can better focus your search and eliminate, in some cases, thousands of search results that are not going to be helpful to you. Learning to join your search terms with Boolean operators will make you a more efficient searcher and save you time as you go about your research.
A Boolean search is most frequently used when your initial search query returns far too many hits, many of which appear to be unrelated to your topic. If you go to one of our article databases and enter a very broad search term such as nursing or psychology or AIDS you will retrieve tens of thousands of articles. As you look through your results you will discover that the articles cover any and every imaginable subtopic within those areas. By using the Boolean strategy to focus your search more specifically, you will discover that the results will be more relevant and, therefore, more helpful to you.
These are the three Boolean operators:
AND - this is the most commonly used operator because it helps researchers narrow their focus when searching for information. The AND operator causes the database to return to you only those articles that contain both or all of your search terms. For example, automobiles AND injuries will locate articles about automobile-related injuries but not articles about automobile manufacturing or household injuries. Cancer AND smoking AND women will find articles that deal specifically with smoking-related cancers in women.
OR - this is the opposite of the AND operator in that the OR operator is used to broaden a search. A search with the OR operator will find all the articles that include at least one of the search terms in your query. If you want to make sure, for example, that you locate all the articles in a database that deal with the human lung you might want to use this search query: lung OR pulmonary OR respiratory. This search will return every article that mentions at least one of these terms. Be careful when using the OR operator with broader terms. A search for education OR computers will return tens of thousands of articles. The OR operator is best used with very specific search terms.
NOT - this operator allows you to narrow your results to a sub-topic within a broader topic. If, for example, you need articles about casinos but not about those on Indian reservations you can use the following query: casinos NOT Indian.
COMBINING DIFFERENT OPERATORS - the different operators may be combined with a single search query. If your topic is crime in the outstate Michigan region, for example, you can enter crime AND Michigan NOT Detroit.
Becoming familiar with Boolean searching will make you a more efficient researcher. If you have any questions or need any assistance please Ask A Librarian.
