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FAQ: What is controlled vocabulary?
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  1. What is a controlled vocabulary?
  2. Why is using a controlled vocabulary important?
  3. What is indexing?
  4. What bridges the gap between the user’s natural language and the controlled vocabulary?
  5. What does mapping mean?
  6. How is a controlled vocabulary used?
  7. What are some of the advantages in using controlled vocabulary for information resources?
  8. Where do the terms and concepts in a controlled vocabulary originate?
  9. Is there a controlled vocabulary just for dentistry?
  10. What is the best way to see controlled vocabulary in action?

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  1. What is a controlled vocabulary?

  2. 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.

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  3. Why is using a controlled vocabulary important?

  4. 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.

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  5. What is indexing?

  6. screenshot 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.

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  7. What bridges the gap between the user’s natural language and the controlled vocabulary?

  8. In a controlled vocabulary, different types of terms can be associated with the same concept:

    • A preferred term is the word or phrase that is used consistently to represent a concept. Think of it as the controlled vocabulary’s “official” term for that concept.
    • An entry term is either a synonym of the preferred term or closely related to it in some other way. It is explicitly associated with the preferred term and is used to guide the user to it.

      Example from MeSH:
      Laughing Gas is an entry term for the preferred term Nitrous Oxide.

      Most concepts in MeSH have more than one entry term.
      Example: Canker Sore and Aphthous Ulcer are both entry terms for the preferred term Stomatitis, Aphthous. So are the variants Sores, Canker and Ulcers, Aphthous.
    • Entry terms are a type of non-preferred term. Non-preferred terms are synonyms or other relatives of preferred terms. In a search engine, a non-preferred term that isn’t an entry term may still be used to guide the user to the preferred term, depending on the way that the search engine maps the term.

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  9. What does mapping mean?

  10. 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.

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  11. How is a controlled vocabulary used?

  12. 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.

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  13. What are some of the advantages in using controlled vocabulary for information resources?

    • A controlled vocabulary increases indexing consistency. When incorporated into a search engine such as PubMed, it helps to narrow subject areas and make search results more precise.
    • Using controlled terms makes it easier to bring together resources that are relevant to each other.
    • With a preferred term, a user searching for information on a particular subject doesn’t have to think up all the different ways that the subject might be expressed by authors and type them into the search. The preferred term automatically includes synonyms and other closely related terms.

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  14. Where do the terms and concepts in a controlled vocabulary originate?

  15. 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.

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  16. Is there a controlled vocabulary just for dentistry?

  17. 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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  18. What is the best way to see controlled vocabulary in action?

  19. Try these exercises:

    • Exercise #1
      Search MEDLINE using PubMed.  PubMed is available at http://www.ncbi.nlm.nih.gov/pubmed/.  Type “oral cancer” into the search box.  After searching, click on the “Details” tab and look at the “Query Translation”, which shows which MeSH preferred and non-preferred terms (if any) your search was mapped to and how the search was executed.
      pubmed_screen
    • Exercise #2
      Play with the MeSH Database  The MeSH Database can be accessed at http://www.ncbi.nlm.nih.gov/sites/entrez?db=mesh. (Don’t be tricked – the MeSH Database access website looks very similar to the PubMed website.)  The MeSH database is used to index articles for PubMed.

      Start by searching for the term oral cancer, which maps to Mouth Neoplasms. Open the Mouth Neoplasms MeSH record (below).

      Scroll down to see a complete list of the Entry Terms for Mouth Neoplasms. Scroll down further to see how Mouth Neoplasms fits into MeSH’s hierarchy or “tree” system.
      pubmed

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Last update: Feb. 5, 2015
Authored by: Evone Jeffries

 

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Comments:

dr.nair (14 ), 12/30/2009:
Nice its new to me

 

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