Subject headings describe the content of each item in a database. Use these headings to find relevant items on the same topic. Searching by subject headings (a.k.a. descriptors) is the most precise way to search article databases. It is not easy to guess which subject headings are used in a given database.
Keyword searching is how you typically search web search engines. Think of important words or phrases and type them in to get results.
Here are some key points about each type of search:
Keywords
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Subjects
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- natural language words describing your topic - good to start with
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- pre-defined "controlled vocabulary" words used to describe the content of each item (book, journal article) in a database
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- more flexible to search by - can combine together in many ways
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- less flexible to search by - need to know the exact controlled vocabulary term
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- database looks for keywords anywhere in the record - not necessarily connected together
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- database looks for subjects only in the subject heading or descriptor field, where the most relevant words appear
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- may yield too many or too few results
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- if too many results - also uses subheadings to focus on one aspect of the broader subject
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- may yield many irrelevant results
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- results usually very relevant to the topic
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