Research is often an iterative process whereby the process of conducting the research will give rise to new ideas which, in turn, feed back into the data collection and analysis stage. When conducting research in library research resources or a web search engine, you will need to experiment with different search strategies as you develop your searches, locate relevant resources and identify additional keywords to use that best represent the aspects of the topics you are researching.
Boolean operators are a set of commands that can be used in almost every search engine and database, including Omni, an article index such as Sociological Abstracts and search engines such as Google Scholar. The most popular Boolean commands are AND, OR, and NOT. Other commands include parentheses, truncation, and phrases. Boolean operators can help save you time because they can improve the relevancy of your search results and make your searching more efficient.
Using the Boolean command AND in your search tells the search engine to give you results that contain all of the words you have entered
globalization AND canada: only those results that contain both globalization and canada will appear in your search results list.
Using Boolean command OR in your search tells the search engine to give you results that contain any of the words you have entered.
teenagers OR adolescents: any results that contain either teenagers or adolescents will appear in your results list.
Using Boolean command NOT in your search tells the search engine to give you results that contain the word(s) you entered except the word following NOT.
cloning NOT sheep: any results that contain the word "cloning" will appear in your results list except those results that also contain the word "sheep". Use NOT sparingly, if at all, as you may end up inadvertently excluding results that are relevant.
Most library databases provide the option to select Boolean Operators on the Advanced search screen, so all you have to do is select the operator you want from a drop down box between search boxes, as with the following example from the ProQuest database International Bibliography of the Social Sciences.
Boolean Operator: AND
Use AND when your research topic has more than one key term that must be present in all of your search results. In this example, use it to link the key terms art and activism so that both concepts appear in all of your search results. Searching with AND gives you fewer results.
Boolean Operator: OR
Use OR when there are other terms that could also be used to describe the topic, including synonyms, related terms or words and phrases that have similar meaning. In this example, use OR to link art and aesthetic, and to link activism and protest, so that you'll get results with either concepts. Searching with OR gives you more results.
Boolean Operator: NOT
Use NOT when you want to exclude results that contain a particular word, phrase, or topic, or when your research topic is often closely associated with another concept you do not want information about. Using NOT will eliminate all search results that include the unwanted concept. Use NOT sparingly, if at all, as it could exclude results that are ultimately relevant. Searching with NOT gives you fewer results.
Before you start your research, consider developing a list of keywords that best describe your topic.
Thesauri, specialized dictionaries and encyclopedias are all useful resources for learning more about aspects of your topic and will give you synonyms, additional keywords and subject-specific terms that can be used in your searches.
Here is an example of breaking down a topic into keywords:
Prisons (main keyword)
Ensure that your keywords are kept together by surrounding phrases wtih quotation marks (" "). If you have a keyword that is more than one word, such as human rights, you would type "human rights" into the search box to ensure the words human and rights don't get searched separately. In most databases, AND is assumed between each word, by using quotation marks you are ensuring that your keywords are kept together in their intended meaning.
Whenever you have more than one Boolean operator, such as AND and OR, in a search statement, it is necessary to separate them with parentheses. This is known as a "nested searching." Here's an example:
("social movements" OR activism) AND globalization
Nested searching tells the database the proper order in which to search for the keywords. Operations enclosed in parentheses are performed first followed by the operators outside the parentheses.
An asterisk (*) may be used to specify any number of characters. It is typically used at the end of a root word, when it is referred to as "truncation." This is great when you want to search for variant endings of a root word.
For example: searching for educat* would tell the database to look for all possible endings to that root. Results will include educate, educated, education, educational or educator. Use the truncation symbol with caution.