Ovid Tips

Subject/Textword Searching

A SUBJECT search and TEXTWORD search on MEDLINE are very different and can produce varied results. Each searching technique has a significant and unique function so it is important to know when to use each method. A Subject search will find citations that are ABOUT a topic, whereas a Textword search looks for citations that CONTAIN your terms in the title and/or abstract.

Subject Searching

A Subject search looks for citations that are ABOUT a certain topic. You do this type of search by using the National Library of Medicine's (NLM) controlled vocabulary or thesaurus. These controlled vocabulary words are called Medical Subject Headings (MeSH), and provide controlled access to the MEDLINE database.

A distinctive feature of MEDLINE is the careful and extensive indexing of articles done by subject specialists using this controlled vocabulary. The NLM indexers read the articles and assign the most specific MeSH terms appropriate to describe the concepts (approximately five to fifteen). To retrieve citations on a particular topic, you should select the appropriate MeSH vocabulary to cover the concepts.

There are special search engine features to help you find and use these Subject Headings. Subject searching is a very comprehensive way to search and is usually the recommended method.

When searching, put in ONE concept at a time. You will combine these concepts later. THIS IS VERY IMPORTANT!! If you put in more than one concept using AND or OR (i.e., asthma AND therapy; emphysema OR fibrosis), you will not be doing a Subject search. When the system "sees" the AND or the OR in the same sentence, it will automatically look for your words only in the titles and abstracts of articles. This would be a Textword search (see below), not a Subject search; you may not find all the articles that are ABOUT your topic.

 

Textword Searching

A Textword search provides either an alternate or a complementary approach to Subject searching. If you do not have success using the MeSH terms, consider using Textwords; they can provide a great deal of flexibility. As comprehensive as the MeSH vocabulary is, not every topic is included. In such instances, it is possible to do a search using your "own" words.

When you enter a term for a Textword search, the system will look for it in the title and/or abstract of the citations. Since Textwords are not controlled, you are entirely dependent upon the language of the author. It is also important to realize that citations found through a Textword search may CONTAIN your search terms in the titles and/or abstracts, but the articles themselves may not be ABOUT your topic.

 

Examples:
If you do a Textword search using the term "asthma," the system will look for that word only in the title and/or abstract of the citations. It will not search for articles that are ABOUT asthma. Consequently, your retrieval could have articles that are about heart disease in a patient whose family history included asthma.

If you do a Textword search using the term "AIDS," the system will retrieve articles that have the term in the title and/or abstract. The articles may be about Acquired Immunodeficiency Syndrome, or about hearing "aids."

We suggest you use textword searching for:

These various ways of expressing a single concept should be "ORed" together for a comprehensive retrieval.