Generally, there are two different techniques you can use for searching an index or database: textwords (or keywords) or controlled vocabulary terms. The type of search terms you use will mainly depend on the database you are using. It is always good to know whether the database uses textword searching, a controlled vocabulary or both. Use the tips below to improve your search techniques!
Textword searching is also known as natural language, free text or keyword searching. Google is a prime example of textword searching. When you search Google, you type in the textwords you want to find and Google will search on these terms. Textword searching does not take into consideration variant spellings (e.g. pediatrics vs. the British paediatrics), nor does it search for synonyms of a search term (e.g. a search done on heart attack will not retrieve articles that use the term myocardial infarction).
In order to perform an effective textword search, incorporate the techniques below.
When searching using textword searching, truncation is an effective means of finding plurals or variants of terms. Truncation allows you to add a symbol to your search term so that all variants of the word appear. The word cell* retrieves articles with the words: cell, cells, cellular, cellulite, cellophane, cellist, and cellphone. With some databases, you can also use truncation in the middle of a term: Wom?n will retrieve women or woman. Please note, this feature is not available in PubMed.
Another technique to keep in mind is to use the Boolean operator OR to link together similar concepts. Use (head injur* OR head trauma OR brain injur* OR brain damage) to find information on head injuries. Entering "like" terms (synonyms) using OR need should be enclosed in parentheses, often called nesting.
For example to retrieve articles discussing head injuries and intracranial pressure, a sample search strategy would look like:
(head injur* OR head trauma OR brain injur* OR brain damage) AND (intracranial pressure OR intracerebral pressure OR subarachnoid pressure)
Another technique used for textword searching is phrase searching. Most databases allow you to put your phrase in quotation marks in order to search for the phrase exactly as it appears, an example of this would be fetal alcohol syndrome. Always check to see how the database searched your phrase because it may not recognize the terms as a phrase.
For example, if you enter: health information exchange in PubMed, it runs the search as "health information exchange"[MeSH Terms] OR ("health"[All Fields] AND "information"[All Fields] AND "exchange"[All Fields]) OR "health information exchange"[All Fields].
To force the database to search the entered terms as a phrase, enter them in quotes (single or double quotes depending on the database).
For example, if you enter "health information exchange" in PubMed, it will run your search as "health information exchange"[All Fields].
A controlled vocabulary uses a specific term for a number of synonyms. Once you find the correct term, you do not need to use synonyms in order to perform you search. An example of a source that uses a controlled vocabulary is the yellow pages of the telephone book. Car dealers might be listed under the term automobile dealers. A controlled vocabulary employs a thesaurus, which outlines which term should be used for a concept. For example, MEDLINE employs the MeSH thesaurus (Medical Subject Headings). The MeSH term for breast cancer is breast neoplasms. An article written about breast cancer will be indexed under the term breast neoplasms even if the phrase breast neoplasms is not used by the authors of the article.
A controlled vocabulary allows you more control in choosing search terms. Some techniques that you can use when searching with a controlled vocabulary are outlined below:
Hierarchical structure
Broader, Narrower and Related Terms
Major or Starred Terms
Working Backwards
Examples of LRC databases that use a controlled vocabulary:
