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Expert Keyword Searching

Modifying an Unsuccessful Search

If you aren't happy with the list of articles your search brings back, here are some ways you might think about changing your search.

1. Too many articles / Articles aren't on topic

  • Make your topic more specific. You could add words, using the AND connector, to describe the
    • population
    • setting
    • treatment or intervention
    • outcome
  • Make the ideas within your topic more specific. For example
    • "women" becomes "women over 50"
    • "analgesic" becomes "opioid"
    • "recovery" becomes "length of stay"

2. Too few articles

  • Make your topic less specific
    • focus on the core ideas (remove unnecessary details)
    • choose less specific terms ("exercise therapy" becomes "exercise")
  • Look for different search words 
    • brainstorm synonyms (e.g. "length of stay" = "hospital stay") or different forms of a word (e.g. therapy, therapies, therapeutic) and then use the OR connector to add them to your search.
    • scan abstracts and subject headings to find out which words authors and databases are using to describe your topic.

Photo by Anant Nath Sharma, used with permission under a Creative Commons license

Keywords and Subject Headings

Keywords

When you search with keywords, you are trying to find words that authors have used in their titles and abstracts or somehow otherwise appear in the article's entry in a database. Therefore you need to brainstorm all of the possible ways authors could refer to your concept:

"endurance" OR "physical fitness"

"education" OR "training" OR "school" OR "learning"

Subject Headings

You can also search using subject headings. Subject headings are keywords assigned by the databases to describe the concepts in an article and to try to take some of the guesswork out of the job of coming up with keywords. Try searching with subject headings and see how your results differ from searching with just keywords.

Still unsure about subject headings? Watch this video for another explanation as well as tips on how to find them.

Subject Headings Variations by Database

Every database calls them different names and handles how they're assigned differently:

  • PubMed = MeSH (Medical Subject Heading)
  • Medline = MeSH
  • CINAHL = subject heading
  • APA PsycInfo = subject heading
  • ERIC = descriptor

The databases also each create their own list of standardized subject headings and use different labels to indicate when a term is a subject heading, as opposed to a keyword. So you will not be able to use the same search across databases. The keywords will most likely stay the same, but your subject headings will need to be translated for each database.

  • PubMed = "Carbonated Beverages"[MeSH]
  • CINAHL = MH "Carbonated Beverages"
  • APA PsycInfo = "Beverages (Nonalcoholic)"/
  • ERIC = no equivalent descriptor, but here's an example of a labeled descriptor: DE "Drinking"

A note of caution: subject heading assignment is not always perfect, and not all articles in PubMed are assigned MeSH terms. Given the fact that you want an exhaustive search when completing a scoping or systematic review, it would be best to include both MeSH terms and keywords in your search to prevent missing articles.

Want to geek out over Automated Indexing at the National Library of Medicine to find out more about how PubMed's subject headings are assigned? Check out the FAQ below!

Revising Your Search