Textword Searching Versus Controlled Vocabulary
There are two different types of searching techniques for searching an index or database. They are: textword (or keyword) and controlled vocabulary searching. The type of search terms you use will mainly depend on the search engine that you are using. It is always good to know what the database you are using and whether it uses textword searching or controlled vocabulary. Use the tips below to improve your search techniques!
Textword searching is also known as natural language, free text or keyword searching. The Google search engine is a prime example of textword searching. When you search Google, you type in the textwords that 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 disease will not retrieve articles that use the term cardiac disease).
In order to perform an effective textword search, incorporate the search techniques below:
When searching using textword searching, truncation is an effective means of finding plurals or variants of the 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. You can also use truncation in the middle of a term: Wom*n will retrieve women or woman.
The truncation symbol depends on the database that you are using.
- Using the Boolean Operator OR
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.
While MEDLINE uses the MeSH thesaurus, keyword searching is also possible in PubMed especially if you are doing a tagged search (that is searching for words in the title or abstract). For more information on using truncation in PubMed go to PubMed's truncation skill kit.
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.
Examples of RCS databases that use textword searching:
- Current Contents Connect
- DIALOG databases
- Cochrane Libraries
- PubMed (both textword and controlled vocabulary)
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.
A controlled vocabulary allows you more control in chosing search terms. Some of the techniques that you can use when searching with a controlled vocabulary are outlined below:
Another advantage of controlled vocabulary is the hierarchical nature of the thesaurus. For example, a search for Central Nervous System Diseases would include the term Encephalomyelitis. If I wanted information on central nervous system diseases, including encephalomyelitis, I could search on the broader term. If I wanted information only on encephalomyelitis, I could go directly to the more specific term.
- Broader, Narrower and Related Terms
Most thesauri include broader terms (BT), narrower terms (NT), and terms that are used for other terms. In addition, sometimes other terms are suggested which might be related. For example, in MeSH, a broader term for Breast Neoplasms is the MeSH term Breast Diseases. A narrower term for Breast Neoplasms is Breast Neoplasms, Male.
In addition, a list of terms are included that are all terms that are indexed under Breast Neoplasms they include: Breast Tumor, Tumor, Breast, Neoplasms, Breast, Tumors, Breast and Breast Cancer. The MeSH term Breast Neoplasms does not have any related terms suggested. For additional information on using MeSH , go the NLM's MeSH Fact Sheet.
Another advantage of using a controlled vocabulary is the ability to designate one or more of your terms as major terms that designate that they are the major topics of the article, usually obtained from the title and/or statement of purpose.
One of the advantages of a controlled vocabulary is that once you find the appropriate term, you can use that term to find other items indexed under that term. In the LRC’s catalog, subject terms are listed for each item with active links to those terms. Look in the LRC's online catalog for the book Case Studies in Nursing Ethics.
Notice that one of the subject headings that appear at the bottom of the screen is Ethics, Nursing.
If you would like to find more books on nursing ethics, click on the subject heading, Ethics, Nursing.
Examples of RCS databases that use a controlled vocabulary:
- The LRC online catalog
Here are links to a few tutorials on searching using controlled vocabulary:
For further information, contact the Reference Librarian.