2008SpringQ1Response

//Using controlled vocabulary terms from authority lists in thesauri or subject heading lists can have powerful effects on search success. What features of controlled vocabularies affect search success? Identify and describe three of these significant features and discuss how each feature affects search success positively and/or negatively//.

[Maryke - from 530 notes] Controlled vocabulary is used to promote consistent representation of subject matter, and ensure the collocation of related materials.

Controlled vocabulary:
 * controls synonyms
 * controls word forms
 * controls homographs
 * provides cross-references
 * provides hierarchy (thesauri)
 * deals with concepts, not just words
 * the structure provided can be used in online architecture

Negative aspects of controlled vocabulary:
 * can become outdated
 * requires familiarity with terminology and structure
 * is only as good as the indexer
 * is only as good as the thesaurus
 * is restrictive
 * may result in low recall

Possible answers: controlled vocabulary can increase precision in search results by its use of authorized terms to control synonyms, word forms and homographs. For example, use of the subject heading "Indians of North America" will retrieve many works about Native American peoples including Sioux, Navaho and Pamunkey; it will also avoid the false drops that would occur if the searcher simply entered the term "Indians". This same subject heading reveals some of the problems with the use of controlled vocabulary. The term is outdated and tends to confuse and/or offend a good number of users. It requires familiarity with the Library of Congress Subject Headings, which often don't correspond with what most would consider natural language. The LCSH are a language for experts, which means that novice users must either know to ask for help, or take their chances. A novice user would also be unfamiliar with the hierarchy of LCSH and the concept of appropriate levels of specificity in cataloging. She would not know that a book written exclusively about the Navaho probably would not have the above subject heading, and might be unpleasantly surprised to find it left out of the search result set: use of the controlled vocabulary, while increasing precision, also results in lower recall.

Literary warrant is another aspect of controlled vocabulary that can both help and hinder searchers. Terms are created as materials are received that require new terminology. This creates room for changes in subject fields due to specialization, growth, and changes in terminology used by certain professions. But it also means that novices have a significant barrier to access in that they have to be familiar with this principle in order to know that they may need to use multiple subject terms to retrieve everything on their topic, because new terminology is constantly being added. Good authority control can reduce these difficulties. Conversely, the relative flexibility of a system using literary warrant can frustrate those who expect new terminology, but don't see it being added quickly enough. In fields such as computer science and popular culture, subject terms are not being created quickly enough to please some searchers.

Finally, in order to be effective, controlled vocabulary must be specific and consistent in its application for a certain audience. Even a broid system such as LCSH still assumes that the searcher is Western, English, speaking, and at a higher level of education. Examples of systems targeted to more specific audiences are MESH (medical community), INSPEC (engineers) and ERIC (educators). While the use of terminology known to a certain community makes searching very easy for members of that community, it will frustrate anyone from a different discipline. It is for this reason that ontologies, providing translation between different subject vocabularies, are promising to be so useful to searchers.