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How to search in the health sciences

To view this video in full screen:

  1. play the video
  2. click on the "cog" icon
  3. select "enter full screen"
  4. to exit full screen hit the escape (ESC) key

To view this video in full screen:

  1. play the video
  2. click on the "cog" icon
  3. select "enter full screen"
  4. to exit full screen hit the escape (ESC) key

The importance of brackets

Databases do not know which terms in your search are synonyms and which ones are different and will combine them in the order they are entered in search box, if you are not careful about how you do this you will not get the results you are seeking. Mixing ANDs and ORs together in your search string can have unintended consequences as well. If you need to mix your boolean operators in one search string you need to use brackets to tell the database how to group your terms together. Just like in math the operations inside the brackets are conducted as a step in the over all search.

  • Group synonymous terms using parentheses with OR in between those terms.
    •  e.g. (teen OR teens OR teenagers OR youth OR adolescent OR adolescents)
    • The database will search this as a group first before combining it with the next term or group of terms
  • Combine the groups of synonymous terms using AND. 
    • e.g. (teen OR teens OR teenagers OR youth OR adolescent OR adolescents) AND (driver OR drivers OR driving)

This search string directs the database to first search all the terms relating to teens between the brackets to create one group. Then the database searches for all the terms relating to drivers listed between the brackets to create another group.  Then the database combines those two groups together.  

This finds any results including any of the first group of terms as long as the results also include any of the second group of terms.

Note: As general rule, only use the OR operator within parentheses.

What difference to brackets make?

What difference do brackets make?

screen capture of cinahl search history explained below

This is a screen capture of the CINAHL search history table with three different versions of a search.  

Version 1 (1,755 results)

In this version the example is broken down into separate search strings.  The teen terms are OR'd together and searched in S1 (222,245 results).  The driver terms are OR'd together and searched in S2 (42,903 results). Finally the two groups are AND'd together and searched in S3 (1,755 results).  This is the ideal result. Any results including any of the first group of teen terms as long as the results also include any of the second group of driver terms.

Version 2 (263,393 results)

In this version both groups are included in the search with OR's and AND's mixed together in S4 (263,393 results).  The database is left to interpret how the AND's and OR's fit together.  This has left us with unintended results.

Version 3 (1,755 results)

In this version both groups of terms are carefully delineated by the use of brackets and searched in S5 (1,755 results).  This is identical to the results in Version 1 which is what we really wanted.  In this case though with fewer steps.