A handy strategy to use when searching a periodical articles database or the entire Internet using a search engine such as Yahoo or Google is what is called a Boolean search. By using this strategy you can focus your search query and eliminate, in some cases, thousands of search results that are not going to be helpful to you. Becoming familiar 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, the majority of which appear to bear no relevance to your topic. If you go to one of our periodical articles databases and enter a very broad search term such as nursing or psychology or AIDS you will come up with tens of thousands of articles. As you look through your results you will discover that most of these articles have nothing to do with the particular aspect of the topic you are researching. By using a Boolean strategy to focus your search more specifically you will discover that the results of your search will be more relevant and, therefore, more helpful to you.
Three Boolean operators
AND – this is the most commonly used operator because it helps researchers narrow their results when searching in large databases. The AND operator causes the database to return to you only those articles that contain both or all of your search terms. For example, football AND injuries will locate articles about football-related injuries but not articles about fantasy football leagues 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 more 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 Minnesota region, for example, you can enter crime AND Minnesota NOT Twin Cities. Or you can search for the opposite by using crime AND Minneapolis OR St. Paul.
Becoming familiar with Boolean searching will make you a more efficient researcher. If you have any questions or need any assistance please contact a librarian.