Subject Searching

Most databases (like catalogs and indexes) have subject headings assigned for each book or article included in the database. Subject searching involves searching for the exact term that the indexer or cataloger has used to describe the item. These terms, which ensure that all items about the same topic have consistent subject headings, are in a database field called a subject or descriptor field. Using the correct subject headings, researchers can retrieve all the items on a topic, even when there may be several good ways to state a concept.
Often there is a list of these terms, e.g. Library of Congress Subject Headings, National Library of Medicine Subject Headings, Thesaurus of Psychological Terms, ERIC Thesaurus, Sociology Terms.

For example, you may want to research the topic death penalty:

Possible ways to state this topic:
• Death Penalty
• Electrocution
• Capital Punishment
• Hanging
• Cruel and Unusual Punishment
• Death Row
• Lethal Injection
The same term may not be used in all databases. If you are unsure whether a database has a thesaurus, ask a reference librarian.

Keyword Searching

A keyword (also called word or free text) search retrieves words or phrases from several important fields of the records in a database. In most databases a keyword search finds words in fields that have descriptive content, such as title, author, subject/descriptor, content field and abstract . In some databases, additional fields may be included in the keyword search.

A keyword search usually retrieves more items than a subject search, but they may not all be relevant. In a keyword search you can retrieve a number of irrelevant items because the computer is looking for the exact word you typed, not just for the idea you are researching.

For example, a search on AIDS will retrieve items on

• aids for the hearing impaired
• school aids
• AIDS (the disease)

Keyword search is the best method when:

• there is no subject heading for your topic
• the subject heading is too general or too specific
• you are searching for a new trend or concept
• the database does not have subject headings

When searching by keyword, use only the most important words, do not use common or very short words. Such words may be stopwords, words that occur too frequently to search. Stopwords stop the search and you will get no retrievals.

 

What's the Difference?

Subject Searching

• Searches subject or descriptor field only
• Use only controlled terminology (may be from a Thesaurus)
• Many relevant items
• Low retrieval

Keyword Searching

• Searches subject, title, author, content and abstract fields
• May search for any significant terms
• May retrieve many irrelevant items
• High number of retrieval