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Cleveland Clinic Florida - How to Conduct Systematic Reviews: Step 3: Connect your keywords

This guide was adapted from How to Find and Conduct Systematic Reviews by Dr. Barbara Sorondo from Florida International University, and from Systematic Reviews: the process by Duke University.

your to do list

Boolean operators (the words AND, OR, and NOT) are what you will use to connect your keywords.

1. Use AND to connect independent keywords.

  • AND will include all of your terms together in the same search.
  • Example:
    • "sleep deprivation," "REM deprivation"
      AND
    • learn*
      AND
    • "college students," "university students"

2. Use OR to connect related keywords.

  • OR will include any of the connected keywords in the search.
  • Example:
    • "sleep deprivation" OR "REM deprivation"
    • "college students" OR "university students"

3. Use NOT to eliminate irrelevant words. You usually will not use NOT at this stage. 

4. Write out all your keywords with the connectors.

  • Example:
    • "sleep deprivation" OR "REM deprivation"
      AND
    • learn*
      AND
    • "college students" OR "university students"

5. If you have more than one keyword in a row, wrap parentheses around the entire row. This is called nesting and keeps related concepts together.

  • Example:
    • ("sleep deprivation" OR "REM deprivation")
      AND
    • learn*
      AND
    • ("college students" OR "university students")

6. Examine your search phrase for redundancies. Are you repeating words unnecessarily? If so, consider connecting the words with AND and OR instead of using quotation marks. However, do not remove quotation marks from phrases consisting of words that must always go together in the same order.

  • Example:
    • ("sleep deprivation" OR "REM deprivation") - Leave as is.
      • We will leave the quotation marks even though we are repeating the word "deprivation" because "sleep deprivation" and "REM deprivation" are phrases consisting of words that are always used together in the same order. For example, "deprivation of sleep" is seldom, if ever, used.
    • ("college students" OR "university students") → (student* AND (college* OR universit*))
      • We will remove the quotation marks and use Boolean operators instead. Though "college students" and "university students" are common phrases, the two words do not necessarily always go together in the same order. For example, you will frequently hear "students at the college of X" or "students at Y University." As an added bonus, since we removed the quotation marks, now we can add asterisks to look for both the singular and plural forms of the words. (And, yes, you can use multiple parentheses.)

7. Write your full search phrase. The full search phrase should include all your keywords with quotation marks, asterisks, Boolean operators, and parentheses as applicable. You can put everything back in the same row now or, if you prefer, keep different keywords in different rows for the time being.

  • Example (Everything in One Row):
    • ("sleep deprivation" OR "REM deprivation") AND learn* AND (student* AND (college* OR universit*))