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Library Research Skills for Land and Food Systems

Subject headings

Limitations of keyword searching

Up to this point, all of our searches have been keyword searches. Sometimes, keyword searches can be frustrating because:

  • you retrieve results which just mention your keyword briefly;
  • you find articles which use your keywords in a different context and are not actually about your topic;
  • you are left wondering: have I found the best articles about my topic or just a random selection?

One of the best ways to improve the completeness of your search and reduce these frustrations is by using subject headings.

What are subject headings?

Subject headings are the human-assigned, controlled vocabulary used to describe the subject matter of an article: what is the article about? (In addition to being called subject headings, they are sometimes called subject descriptors, MeSH - medical subject headings, CINAHL headings, etc. depending on the article index). more info...

  1. Subject headings make your search results relevant:

    Subject headings are like tags that tell you the primary topics covered in the article. CAB Direct, Medline, Zoological Record, and many other discipline specific databases, have subject headings that allow you to make your search more relevant.

  2. Subject headings make your search results comprehensive and complete.

    As you may imagine, authors may use various words to talk about the same subject. Therefore, if you do a keyword search using a different word from the one chosen by an author, you will miss their article. By using Subject headings, you find all of the articles that are about your topic, including ones where the authors are using different words or phrases.

Note: Not all indexes have subject headings. For example, Summon does not have subject headings. If you are uncertain if an index has subject headings, you can look at the index's help page, or ask a librarian.