A useful way to use Boolean Operators is to group them together. Using AND, OR, and NOT in groupings will provide more results in one search.
(climate change or greenhouse effect) AND (food security OR food insecurity OR food sustainability)
Truncation and Wildcards are useful to find variations or alternative spellings of a word.
The "Subject" limiter in the databases use the Library of Congress Subject Headings (LCSH). Subject Headings are a type of controlled vocabulary or thesaurus. Subject Headings are more specific than basic keyword searching.
As you can see below, using the Advanced Search feature allows you to search in groups and by different fields (methods). This Subject Heading search filtered the results to only give LCSH records. In this database, the term is SU subject terms; however, different databases may use different words for Subject Headings. For example, some databases use the terms DE (descriptor EXACT).
Another useful way to refine search terms is by using the controlled vocabulary for each database. These controlled vocabularies help you find the terms for your searches that bring back the best results. The terms used in the controlled vocabularies function similarly to #hashtags for social media. If you search the correct hashtag, you can find other posts on a given subject, but if you alter the terminology, the result is not the same.
You will encounter many different names for these vocabularies, including Thesaurus, Subject Terms, and CINAHL Headings. In an Ebsco database this controlled vocabulary is on the main search page at the top. To access the controlled vocabulary in a ProQuest database, you must first click on the "Advanced Search" tab. See the examples below.
In the EBSCO Database, CINAHL, popular in Nursing, you see "CINAHL Subject Headings" at the top of the main page. It is this way in most EBSCO Databases.
While many students initially use the term "breast cancer," a search within CINAHL Subject Headings shows that articles in the database actually use "breast neoplasms," as you can see in the screenshots below.
These tools also display broader or narrower terms to help you expand or focus your search. In this example, you'll see that the broader term for "breast neoplasms" is "neoplasms" and one of the narrower terms is "Hereditary Breast and Ovarian Cancer Syndrome." This could be helpful if you are getting too few or too many results with your current search.
After searching for "intimate partner violence" in the Psychology Database Thesaurus from ProQuest, you can see that this database uses the term "domestic violence instead. These screenshots give you an idea of how the thesaurus looks in ProQuest Databases. Remember, you have to go to the "Advanced Search" option at the top to find the Thesaurus.
These tools also display broader or narrower terms to help you expand or focus your search. In this example, you'll see that one of the broader terms for "domestic violence" is "Crimes against persons" and one of the narrower terms is "Adult abuse & neglect." This could be helpful if you are getting too few or too many results with your current search.