The Focus feature is also unique to databases that use a thesaurus. When the creators of the database are assigning Subject Headings to an article, they often recognize that although the article may touch upon many subjects, it is MOSTLY about only a few subjects. It will label those few Subject Headings as representing the main theme, or "Focus" of the article.
At the other end of the process, when you are running a Subject Heading search, you can direct the system to show you only those articles for which your subject heading has been designated as one of the major themes of the article. If you do not use the Focus option, your search will bring up all articles in which your Subject Heading is either a major or a minor theme of the article.
In the search strategy, each database uses its own syntax to indicate when you have searched on a given subject heading as the main concept:
Likewise, within the individual record, each database has its own way of indicating the main themes. Here are excerpts from sample records:
When you use the Focus feature, you will bring up fewer results from your search, but the majority of them will be highly "focused" on your topic. That can be a good thing!
The converse, however, is that you will potentially miss some good articles. That's because whether or not a particular subject is considered to be the main focus of an article is subject to interpretation. Furthermore, depending upon how much (or how little) literature has been published on a given topic, you might want to look at everything that even remotely touches on your topic, in which case you would not want to use the Focus feature.
1. Focus can be a help in the initial stages of a search by showing you articles that are known to be "on topic". After you have read those articles and gained familiarity with the topic, you can then remove the Focus feature to broaden your search to pull up any article that addresses it, however briefly.
2. Focus can help when the topic you are searching is very broad, e.g., diabetes, stroke, heart disease.
3. Focus can be a great tool for situations when you just need something good, quickly. It won't show you everything that has been published on the topic, but those articles it does bring up will be "on topic". This can be a huge time-saver.
Bottom bottom line:
Use Focus very carefully, or maybe not at all. It is fine for when you need something good, fast. But it is generally too restrictive to use for a comprehensive search, especially of the type needed for a systematic review, UNLESS you are researching a topic that has a great deal of literature published on it.