Controlled vocabulary

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Definition

“A controlled vocabulary is a vocabulary consisting of a “prescribed list of terms or headings each one having an assigned meaning.”1 The way a controlled vocabulary defines the relationships between these terms or headings will vary in degree of complexity according to the purpose of the vocabulary, from simple alphabetically arranged flat lists to ontologies with richly defined relationships.” (Currier et al., 2005:9)

“Controlled vocabularies provide a way to organize knowledge for subsequent retrieval. They are used in subject indexing schemes, subject headings, thesauri and taxonomies. Controlled vocabulary schemes mandate the use of predefined, authorised terms that have been preselected by the designer of the vocabulary, in contrast to natural language vocabularies, where there is no restriction on the vocabulary.” (Wikipedia, retrieved 15:03, 28 February 2009 (UTC)).

See also pedagogical vocabulary and all sorts of standards

To do:

• Clear up the relationship of types (classes) defined by a controlled vocabulary and instances. Instances, for example, could be part of an ontology but not of a classification scheme.
• Different use cases, e.g. libarary sciences vs. information technology.

Purpose

A controlled vocabulary is a list of terms (e.g. words, phrases) that is used tag (label) information. According to Wikipedia, Controlled vocabularies solve the problems of homographs (words with same spelling but different meaning), synonyms (different words with same meaning) and polysemes (words with multiple meanings) by ensuring that each concept is described using only one authorized term and each authorized term in the controlled vocabulary describes only one concept. In short, controlled vocabularies reduce ambiguity inherent in normal human languages where the same concept can be given different names and ensure consistency. (retrieved 15:03, 28 February 2009 (UTC))

Types of controlled vocabularies

Currier (2005) distinguish between the following kinds of controlled vocabularies:

Flat list

A simple flat list of terms

Glossary

An alphabetical list of terms with some explanation

Subject headings list

See subject heading. A systematic list of subject headings like the ones used for library catalogues. A subject header provides one of the access points to information.

Taxonomy

In a wide sense almost any kind of well defined list of terms

In one narrow sense, a monohierarchical classification of terms. I.e. a child term inherits in principle the properties of the parent term. E.g. controlled vocabularies are a kind of vocabularies, or XHTML is a kind of XML application which is a kind of formalism for defining a formal grammar. This is the equivalent of a kind of typology.

In another narrow sense: “controlled vocabulary in which concepts are represented by preferred terms, formally organized so that paradigmatic relationships between the concepts are made explicit, and the preferred terms are accompanied by lead-in entries for synonyms or quasi-synonyms” (Willpower Information, retrieved 15:08, 27 February 2009 (UTC)). In other words, one also could define a taxonomy with non-hierarchical relationships, but we would rather call these "thesauri".

Classification scheme

A classification scheme is primarily developed for browsing, rather than as indexing or search tools. ([Pedagogical vocabularies project). We therefore could qualify it as a kind of taxonomy.

Thesaurus

A thesaurus is like a taxonomy or a classification scheme, but richer. Leonard Will defines it as “controlled vocabulary in which concepts are represented by preferred terms, formally organized so that paradigmatic relationships between the concepts are made explicit, and the preferred terms are accompanied by lead-in entries for synonyms or quasi-synonyms” (Willpower Information, retrieved 15:08, 27 February 2009 (UTC).

Joan M. Reitz provides a similar definition: “Also refers to an alphabetically arranged lexicon of terms comprising the specialized vocabulary of an academic discipline or field of study, showing the logical and semantic relations among terms, particularly a list of subject headings or descriptors used as preferred terms in indexing the literature of the field.” (T, retrieved 15:08, 27 February 2009 (UTC)).

Topic map

See topic maps, an ISO standard to organize a forest of resources. It's something in between a taxonomy and an ontology.

Ontology

In computer science, ontology refers to “a model for describing the world that consists of a set of types, properties, and relationship types. Exactly what is provided around this varies, but this is the essential of an ontology. There is also generally an expectation that there be a close resemblance between the real world and the features of the model in an ontology” (Garshol, cited by Pedagogical vocabularies project)

See ontology

Folksonomy

Folksonomies are sets of free tags assigned by users to an object. There can be some emergent organization (via statistical analysis) or at least some visualization as in tag clouds.

See Tagging

Formalisms

Many of todays controlled vocabularies, in particular taxonomies and ontologies are defined in XML and XML applications like RDF and Topic maps or languages built on top of of RDF like OWL or SKOS.

But many other formal, less formal or non-formal ways exist. E.g. LDAP Schemas are built with ASN.1, Abstract Syntax Notation-1 (X.691). An LDAP schema can be considered a hierarchical taxonomy of properties that can describe a person.

Typologies

A typology is a list of types that share similar features. These features are usually described with controlled classification criteria (vocabularies), but also can be determined through analysis of subjective representations, e.g. with repertory grid technique, by analyzing taggings, or statistical content analysis.

Also, there is a distinction between type (the set of objects that share the same or similar features) and the token (the instance). E.g. there exists a type of educational sofware that is called learning management systems and an example (token) would be Moodle.

Links

• Glossary of terms relating to thesauri and other forms of structured vocabulary for information retrieval. (Good).

• Reitz, Joan M. ODLIS — Online Dictionary for Library and Information Science (Good)

• Controlled vocabulary (Wikipedia)

Bibliography

• Currier Sarah, Lorna M. Campbell, Helen Beetham (2005). Pedagogical Vocabularies Review, JISC Pedagogical Vocabularies Project, Final Draft, 23rd December 2005 Pedagogical vocabularies project

• Falconer, Isobel, Gráinne Conole, Ann Jeffery, and Peter Douglas (2006). Learning Activity Reference Model – Pedagogy, LADIE reference model guides, The e-learning framework. word doc -archive (broken)

• Garshol, Lars Marius (2004). Metadata? Thesauri? Taxonomies? Topic Maps! Making sense of it all. Journal of Information Science, 30 (4), pp. 378-391. HTML Preprint.

• Reitz, Joan M. (2004). Dictionary for Library and Information Science, Libraries Unlimited, ISBN 1591580757.