FAQ: What is controlled vocabulary?
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FAQ: What is controlled vocabulary?
Ten Questions You Always Wanted to Ask
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A controlled vocabulary is a predefined list of terms used to describe concepts covered in information resources like textbooks, journals, and online databases. There are dozens of such vocabularies relevant to the biomedical and health sciences. The explanations and examples in this FAQ are based on Medical Subject Headings (MeSH), the United States National Library of Medicine’s (NLM) controlled vocabulary for PubMed. PubMed is the search engine for NLM’s bibliographic database, MEDLINE, which includes records from millions of journal articles in all areas of biomedical and health science, including dentistry.
Natural language—the way people usually talk and write--has an extensive range. There are many ways to say the same thing. For instance car, auto, vehicle, taxi, and Mustang all express the concept automobile. But Mustang is also a type of horse, and taxi not only defines a thing but also describes an action. Controlled vocabulary removes the ambiguity inherent in natural language. For example, if you wanted to find information about car insurance in the Yellow Pages, you would be directed to look under the predefined controlled term auto insurance. Controlled vocabulary helps match the natural language of users with that used to formally describe, organize, and categorize data in information resources such as journal articles and books.
Indexing is a process of assigning specific words and phrases (terms) to represent thoughts or ideas (concepts) contained in
information resources such as books and journals. NLM indexers use the MeSH vocabulary to describe the concepts in MEDLINE’s biomedical journal
article records. Each MEDLINE record in PubMed includes multiple MeSH terms that have been assigned to it by indexers.
In a controlled vocabulary, different types of terms can be associated with the same concept:
Mapping is the process of associating non-preferred terms with terms in the controlled vocabulary or in other utilities that are part of the search engine’s system. PubMed uses automatic term mapping, which matches the user’s search term with not only MeSH preferred and entry terms but also with other known synonyms, variants, and other types of information that are part of PubMed’s information system. Examples: A PubMed search for either White Spots or Tooth Decay will be mapped to the preferred term Dental Caries. White Spots is an entry term for Dental Caries. Tooth Decay is not an entry term, but it is known to PubMed’s system and can be mapped to the preferred term. A PubMed search for Oral Cancer or Mouth Tumor will be mapped to the preferred term, Mouth Neoplasms. Oral Cancer is an entry term for Mouth Neoplasms. Mouth Tumor is not an entry term, but PubMed can match it to other information in the system.
Information resources (journals, books, letters, papers, etc.) that contain content (articles, abstracts, chapters, etc.) about or pertaining to a particular topic are indexed with preferred terms that describe that topic. Other commonly used words and phrases that are similar or equivalent in meaning are used as entry terms to guide the user to the preferred term. These terms can be mapped to help searchers retrieve relevant information.
The vocabulary is maintained by the organizing body that controls it. Such an organization is also responsible for the development and quality assurance of the content. The MeSH Section staff specialists at the NLM are the control authority who revise and update the MeSH vocabulary annually. They also receive suggestions from indexers and users and collect new terms as they appear in the scientific literature or in emerging areas of research. The staff specialists define these terms within the context of existing vocabulary and recommend their addition to MeSH.
SNODENT, the Systematized Nomenclature of Dentistry, was designed as a diagnostic companion to the Current Dental Terminology treatment codes of the American Dental Association. SNODENT will provide dental diagnostic codes for the electronic health record.
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