To implement EBM it helps to convert your information need into an answerable question.
There are two basic types of search queries that most databases use: Keywords and Controlled Vocabulary.
Keyword searching (natural language searching) allows you to enter a search term that you believe best describes the term. While this search strategy will retrieve what you've entered, you also need to search using synonyms and variations of the search term to make sure that you have retrieved all of the relevant records.
For example, if you are looking for information on "heart attack" using a keyword search, you should also search using the terms "heart attacks," "myocardial infarctions" and so on.
Subject Headings (controlled vocabularies) are pre-defined, authoritative words or phrases used by databases to consistently describe and systematically organize content. They can change from database to database. The hierarchical nature of the lists allow broad concepts to be narrowed in a manner that stays consistent within that framework.
Before a record is added to a database, its subject matter is determined. Specific terms that apply to those subjects will be chosen from the pre-determined vocabulary list, no matter what terms the author used in the paper. This way, there is a consistent method for retrieving the same information concepts even though different terminology has been used. For example, the term "heart attack" is always listed as "myocardial infarction" within a controlled vocabulary structure, such as MeSH (Medical Subject Headings), the vocabulary used by MEDLINE.
MeSH (Medical Subject Headings) will be covered later in this orientation.
Adapted from Valpariaso University.