Controlled vocabulary

Controlled Vocabulary in Library and Information Science - Controlled vocabulary is a carefully selected list of words and phrases used to tag information units for easier retrieval. - It solves problems of homographs, synonyms, and polysemes by establishing a clear relationship between concepts and preferred terms. - Preferred terms are chosen based on user warrant, literary warrant, and structural warrant. - Controlled vocabularies handle homographs with qualifiers to ensure each term refers to one concept. - Examples of controlled vocabulary systems include the Library of Congress Subject Headings. Types of Controlled Vocabulary Tools Used in Libraries - Subject headings and thesauri are the main kinds of controlled vocabulary tools used in libraries. - Subject headings describe whole books, while thesauri cover specific disciplines. - Subject headings tend to have terms in indirect order, while thesaurus terms are always in direct order. - Subject headings often use pre-coordination of terms, while thesauri use singular direct terms. - Thesauri list equivalent, narrower, broader, and related terms, while subject headings historically did not. Indexing Languages - There are three main types of indexing languages: controlled, natural language, and free indexing. - Controlled indexing language allows only approved terms for describing documents. - Natural language indexing language allows the use of any term from the document being described. - Free indexing language allows the use of any term, even if it's not from the document. - Indexers choose the level of indexing exhaustivity, which determines the level of detail in describing the document. Advantages of Controlled Vocabularies - Controlled vocabularies improve the accuracy of free text searching by reducing irrelevant items in the retrieval list. - They eliminate ambiguities caused by the inherent ambiguity of natural language. - Using controlled vocabulary can significantly increase the precision of an information retrieval system. - Controlled vocabulary can enhance recall by eliminating the need to search for synonymous terms. - It improves the performance of information retrieval systems compared to free text searching. Problems with Controlled Vocabularies - Controlled vocabulary searches may have unsatisfactory recall, failing to retrieve relevant documents. - Users must have a deep understanding of the controlled vocabulary to avoid missing relevant documents. - Low indexing exhaustivity may result in important aspects of a document not being described with index terms. - Some articles may not be tagged with the correct term if it is considered secondary to the main focus. - Controlled vocabulary requires expertise and careful selection of terms to address these problems.