Focusing your results with vocabulary lists
So far we have talked about identifying keywords in your topic and using them to create a search strategy. This approach is often called keyword searching and it is usually an effective and simple way to search. But most databases offer more than one way to search, and many include subject searching, which differs from the keyword searching we've learned about in the last section.
Subject searching requires you to identify and search with subject headings, which may be different in every database. For example, It is a great way to retrieve materials focused on a topic while avoiding items that are irrelevant. It is also a good way to avoid items that may mention your topic, but not discuss it at length. The information below summarizes some major differences between using subject headings and keyword searching.
- Many databases create a list of all the main subjects covered in the database. This is called a controlled vocabulary. If you've ever used the yellow pages, you are familiar with the idea of controlled vocabulary: identify the correct category name, and it will lead you to a list of items on your topic, be it phone numbers or research articles.
- As the name implies, controlled vocabularies indicate that each term on the "official" list has an exact meaning, for example a health sciences database may determine that the term "administration" refers to administering a medication to a patient, and not to the concept of management, as in business administration.
- Controlled vocabularies also help you to select the correct term from among synonyms. If you are looking for information on cars, for example, it is helpful to know if the database uses the subject heading "automobile," "motor vehicle," or "car."
- Most proper nouns are included as subject headings. So if you are looking for information on William Shakespeare, Microsoft, or China you should find all the articles about these subjects by searching for that subject term.
- Because the database's subject list is created in advance, it may not reflect new terminology or it may use a term different than the one you use. Databases often use see references to direct you to the subject term in the controlled vocabulary. For example:
- you may type in Television Commercials but the computer might respond with the phrase, see Television Advertising. This tells you that the database has put all the information on that subject under the heading Television Advertising.
- your search for the word Saturn may retrieve two subject headings: Saturn (planet) and Saturn Corp. You can then choose the one that applies to your topic.
- To provide some flexibility, many databases allow you to search for any significant word in the database. Such keywords may be found in the title, abstract or subject headings of a record in the database.
- You can use Boolean operators like AND, OR, and NOT, as well as truncation symbols in most keyword searching.
- Keyword searches usually exclude common words like a, an, the, of, for, from, in, which are referred to as stopwords.
- Keyword searching allows you to search for terms which are not necessarily in the database's controlled vocabulary list. So you can search for new terms like "wearable computers" or "outsourcing".
- Keyword searching can result in irrelevant hits. For example, if you search for the keyword "Saturn" you might find articles about the car and articles about the planet all mixed in together.
In the next section, we'll learn two ways to identify subject headings on a topic.