A particularly effective type of field searching involves the subject field and the subject terms in it. Subject terms use controlled vocabulary to group all resources that are about something under the same subject term, regardless of the words used by the authors.
For example, the death penalty and capital punishment mean the same thing; some people use “death penalty,” and others use “capital punishment.” This can cause problems when it comes to searching. If you conduct a keyword search using the phrase “death penalty” the computer only searches for items containing those exact words. It does not search for the term capital punishment even though capital punishment describes the same concept. You could miss a lot of important results!
Source: MIT Libraries
Controlled vocabulary is used to solve this problem. It’s akin to using a hashtag in social media to combine all posts dealing with a topic. One term is selected to serve as the official subject term for a concept and it’s placed in the Subject field. That term will be used consistently throughout the database. It’s possible that the term you’ve used is the same one used as the Subject Term, but you need to check to make sure.
How to Find Subject Terms
The subject terms change for each database so you’ll have to explore each one on its own to discover the terms it uses. Most databases have a thesaurus or subject terms header you can click on to explore.
An excellent way to discover subject terms is to conduct a broad keyword search using the terms or phrases pertinent to your topic. Find a couple of results that closely match what you’re researching and explore the subject terms listed for those records. Choose the subject terms that come closest to what you’re searching for and jot them down.
For example, here’s a record from Academic Search Complete found in a search for “death penalty”:
We can see that our keyword, “death penalty,” is used twice in the title. That helps us know its relevant to our search. However, in the Subject Terms we see that the official controlled vocabulary term for this same concept is CAPITAL punishment. Since capital punishment is another way of saying death penalty, the Subject Term also helps us see this source is relevant to our search.
The Subject Term also tells us that items in this database about the death penalty, capital punishment, or death sentence will be assigned CAPITAL punishment as its subject term in the record---even though the author may have used another term.
Next do a search of those terms in the subject field, which you’ll find in a dropdown menu of search options. You’ll probably find you’ll get fewer results, but they will be better, focused on the topic you’re researching. In this case, the Subject field for CAPITAL punishment will find all results on that topic, so we may find ones we missed out on from just using “death penalty.”
