Boolean Logic

It should be obvious by now that there must be a better way to find results. How many of the thousands of "hits" are really useful to you as a searcher?

Search Engines either explicitly or by the use of Boolean Operators let you place finer control over the searching of its database. Some of the logical operators appear below.

OR

The OR operator is useful for the first phases of a search, when you are not exactly sure what information is available on your topic or what words are used to categorize it. When used between two words, the OR operator instructs the search tool to retrieve any record containing either of the words. For instance, the search query

would retrieve items containing either the word "Eva" or the term "Peron" as illustrated below:

 Once you view the types of items containing either word, you might want to narrow your search by dropping one term and confining your search to the other. For instance, you might find that the records indexed under the term "Peron" are more relevant to your research question than those indexed under "Eva." Or, as in the example below, you might find that the items related to the specific field of "Eva Peron" must contain both words, not simply either one. Because OR is the boolean operator that returns the most "hits" (items meeting the search criteria), search queries containing OR are very broad and sometimes return items that are not relevant.

AND

If you need to pose a more specific query, use the boolean operator AND, which limits results to those items that contain both (or all) of the search terms in your query. Again using the two words from the example above, the search query

would retrieve only those items containing both words in the same item, as illustrated below:

As the shaded area shows, this search query would return a much smaller set of hits, and the items would be more applicable to the field of management accounting.

NOT

The last of the three most common boolean operators is the word NOT. The NOT operator is used to eliminate records containing a particular word or combination of words from your search results.

This search would return all items containing the words Eva and Peron except for those that also contain the word "Madonna," as illustrated below:

When you visit a search site, always read the instructions or help file before beginning your search. Each search engine has different parameters for using upper- and lower-case letters and combining boolean operators. Another good method for refining your search is to run a few searches experimentally to see what results are returned. By browsing through your results list, you can determine whether or not your strategy is returning relevant items. Then, you can construct a search strategy using the boolean operators OR, AND, and NOT to improve your results.

In Altavista, use the + character before a phrase or word to ensure that it MUST appear in the search results. Use the - character to ensure that it the phrase or word MUST NOT appear.

Consider the following search keys. Predict what will be searched for, try the searches and compare at the results. You should be looking for relevancy and numbers.