Boolean Operators connect keywords or concepts logically to retrieve relevant articles, books, and other resources. There are three Boolean Operators:
Venn diagram of the AND connector
Example: The result list will include resources that include both keywords -- "distracted driving" and "texting" -- in the same article or resource, represented in the shaded area where the circles intersect (area shaded in purple).
Venn diagram of the OR connector
Example: The result list will include resources that include the keyword "texting" OR the keyword "cell phone" (entire area shaded in blue); either is acceptable.
Venn diagram of the NOT connector
Example: The result list will include all resources that include the term "car" (green area) but will exclude any resource that includes the term "motorcycle" (purple area) even though the term car may be present in the resource.
A library database searches for keywords throughout the entire resource record including the full-text of the resource, subject headings, tags, bibliographic information, etc.
Example: The keyword list above was developed to find resources that discuss how texting while driving results in accidents. Notice that there are synonyms (texting and "text messaging"), related terms ("cell phones" and texting), and spelling variations ("cell phone" and cellphone). Using keywords when searching full text requires consideration of various words that express an idea or concept.
Example 1: In EBSCO's Academic Search Complete, clicking on the "Subject Terms" tab provides access to the entire subject heading list used in the database. It also allows a search for specific subject terms.
Example 2: A subject term can be incorporated into a keyword search by clicking on the down arrow next to "Select a Field" and selecting "Subject Terms" from the dropdown list. Also, notice how subject headings are listed below the resource title, providing another strategy for discovering subject headings used in the database.
When a search term is more than one word, enclose the phrase in quotation marks to retrieve more precise and accurate results. Using quotation marks around a term will search it as a "chunk," searching for those particular words together in that order within the text of a resource.
TIP: In some databases, neglecting to enclose phrases in quotation marks will insert the AND Boolean connector between each word resulting in unintended search results.
Truncation provides an option to search for a root of a keyword in order to retrieve resources that include variations of that word. This feature can be used to broaden search results, although some results may not be relevant. To truncate a keyword, type an asterisk (*) following the root of the word.
Library databases provide a variety of tools to limit and refine search results. Limiters provide the ability to limit search results to resources having specified characteristics including:
In both the EBSCO and ProQuest databases, the limiting tools are located in the left panel of the results page.
The short video below provides a demonstration of how to use limiters to refine a list of search results.
Each resource in a library database is stored in a record. In addition to the full-text of the resources, searchable Fields are attached that typically include:
Incorporating Fields into your search can assist in focusing and refining search results by limiting the results to those resources that include specific information in a particular field.
In both EBSCO and ProQuest databases, selecting the Advanced Search option will allow Fields to be included in a search.
For example, in the Advanced Search option in EBSCO's Academic Search Complete database, clicking on the down arrow next to "Select a Field" provides a list of fields that can be searched within that database. Select the field and enter the information in the text box to the left to use this feature.
Stop words are short, commonly used words--articles, prepositions, and pronouns-- that are automatically dropped from a search. Typical stop words include:
In library databases, a stop word will not be searched even if it is included in a phrase enclosed in quotation marks. In some instances, a word will be substituted for the stop word to allow for the other words in the phrase to be searched in proximity to one another within the text of the resource.
For example, if you searched company of America, your result list will include these variatons:
This short video demonstrates how to create a search string -- keywords connected with Boolean operators -- to use in a library database search to retrieve relevant resources for any research assignment.