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Provides resources, strategies, and information on conducting research in Epidemiology.

A Searchable Question

Begin with a well-focused research question.

What is the dietary intake of dairy products by adolescents in the U.S.?


What are the main terms in this question?

dairy products / dietary intake / adolescents / United States


Synonyms, words that mean the same thing or are closely related to your main search terms, can help expand your search appropriately.  


diary products dietary intake adolescents United States
milk food intake


yogurt diet

Boolean Operators

Boolean operators such as AND & OR are used to connect synonyms & concepts.

  • Use OR to connect synonyms to appropriately expand your search for a concept. Your search results will contain citations for each term.  Place parentheses around the search terms when you use OR so that the database searches them together. 
  • Use AND to connect concepts.  This will narrow your search results, giving you just the articles that include all terms, that is,  the intersection of the search terms you've used.  Remember:  Databases assume AND between terms, so you don't have to use it.
  • Always capitalize boolean operators; if you don't, they'll be ignored.

Building Your Search

Here is the search string that can be used to search the database:

(dietary intake OR food intake) AND (dairy products OR milk OR cheese OR yogurt)

dietary intake & food intake are synonyms for one concept, so they're connected by OR & placed within parentheses.

  • Dairy, milk, cheese, & yogurt are synonyms for the second concept.  They're connected to the first concept with AND.
  • I've left United States out of the search for now.  If my results are large, I'll add it later. 
  • I'll add adolescents by using filters in the database, after I've run my search.  Filters are normally the best way to limit your search by age, sex, language & other factors.
  • Remember, you may not create the best search the first time around.  Based on your search results, you may need to think of new search terms & revise your search.