Last Updated: 27 Jan, 2023     Views: 3

Essentially, a keyword search will look for the actual word you have used in a number of places, such as the abstract, title and lists of keywords given by the author or journal publishers (if a list of keywords as been included). It searches in more places than a Subject Heading search, but it also has a more limited search, as it's looking specifically for the words you have put in the search field of the database.

A Subject Heading is a specific controlled term that has been given to an article based on whether it matches a particular definition. These may be subject headings created by the indexers for the database you are using, or they may be from a regulated list of subject headings, such as MeSH (Medical Subject Headings), which is controlled by the National Library of Medicine in the USA. If you use a subject heading, the keyword you originally used might not turn up at all in some of the journal articles it finds, but the subject it talks about will match the definition outlined in the scope of the Subject Heading.

In database like Medline, CINAHL, etc that let you search for a specific Subject Heading or MeSH term, you have the opportunity to see what the Scope (or definitions) of the subject headings are, so you can pick the one that best suits what you are looking for. When you look at the "tree", you can see if there is a broader, more general term above the Heading you've clicked on, or a narrower, more focused term branching off the term you're looking at. This will let you chose something more appropriate for the information you are trying to find. You may need to try a few different terms to get the full range of results you want.

Both types of searches have their strengths and weaknesses, and we recommend trying both. You'll get some of the same articles in a keyword search that you will get in a Subject Heading search, but you'll also get different results in each. Combining the results of both will get you the broadest range of results, and for some types of research this is what you will be doing. If you would rather only deal with a certain set of results at a time, however, you may wish to run a keyword search and then a subject heading search to have a look at the kinds of results you get for each.