Monday, March 20, 2017

Vocabulary Control

Vocabulary Control
Information Access Through The Subject


The term ‘vocabulary control’ refers to a limited set of terms that must be used to index documents, and to search for these documents, in a particular system. It may be defined as a list of terms showing their relationships and used to represent the specific subject of the document.

An information system may help the user by explicitly assigning index terms (that is, words or notations) to the documents and controlling, at least in the case of alphabetical (word) systems, the  semantic and often the syntatic relationships between these index terms the words (which may be subject  headings or descriptors) are assigned from  recognized subject heading lists or thesauri, and the notations from recognized classification schedules, and thus use controlled vocabulary.  A controlled vocabulary is one in which there is only one term or notation in the vocabulary for any one concept. The Library of  Congress List of Subject Headings is an example of a controlled alphabetical vocabulary, and the Dewey Decimal Classification is an example of a notational vocabulary (By definition, all notational vocabularies must be controlled).

The controlled vocabulary performs several tasks:
  • It usually explicitly records the hierarchical and affinitive/associative relations of a concept. Examples: Allergy, narrower-term: Hay fever; 385 (Railroad transportation), 381.1 (economic aspects of railroad transportation)
  • It establishes the size and scope of each topic. For example, whether or not the word baseball or the notation 796.357 is to include the concept softball.
In addition, for word based systems, the controlled vocabulary identifies synonyms terms and selects one preferred term among them. For homonyms, it explicitly identifies the multiple concepts expressed by that word or phrase. In short, vocabulary control helps in overcoming problems that occur due to natural language of the document’s subject. Hence, if vocabulary control is not exercised different indexers or the same indexer might use different terms for the same concept on different occasions for indexing the documents dealing with the same subject and also use a different set of terms for representing the same subject at the time of searching. This, in turn, would result in ‘mis-match’ and thus affect information retrieval.


Vocabulary Control
  • Subject Heading List
    • List of Subject Headings-General Principles
  • Thesaurus
    • Structure of Thesaurus
    • Relationship Between Terms
    • Thesauri and Subject Headings List
    • Thesauri and Classification Schemes
    • Thesauro-Facet
    • Classaurus
  • Systematic Arrangement

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