controlled vocabularies

controlled vocabularies

Definition

 A controlled vocabulary is an organized arrangement of words and phrases used to index content and/or to retrieve content through browsing or searching. It typically includes preferred and variant terms and has a defined scope or describes a specific domain.

·         A controlled vocabulary is an established list of standardized terminology for use in indexing and retrieval of information.

·          An example of a controlled vocabulary is subject headings used to describe library resources. –(Library & Archives Canada)

Need For Control Vocabulary

·         The need for vocabulary control arises from two basic features of natural language, namely:
 Two or more words or terms can be used to represent a single concept

·         Example:         salinity/saltiness         

·                     VHF/Very High Frequency   

·          Two or more words that have the same spelling can represent different concepts

·         Example:         Mercury (planet)        

·                     Mercury (metal)         

·                     Mercury (automobile)

·         Mercury (mythical being)

How Vocabulary Control is Achieved        

·         Vocabulary control is achieved by three principal methods:

·         Defining the scope, or meaning, of terms
 using the equivalence relationship to link synonymous and nearly synonymous terms; and Distinguishing among homographs.

·         The Standard provides guidelines for constructing controlled vocabularies:

·          selecting the terms, formulating the terms
 establishing relationships among terms, and  pre Purpose of controlled vocabularies:

·         Sending the information effectively in printed, online, and web navigation sites.

·         When librarians became concerned with subject approaches to their stored knowledge records, they quickly came face-to-face with a stubborn fact of life: the complexity, variability and richness of natural language, rather ironically, leads to ambiguity.

·         Using an unlimited or an uncontrolled set of words or phrases, to index and to search a library leads to wasted effort and a certain degree of searching failure due to the enormous range of word choices.

·         In many cases, the user might choose the terms used by the indexer but with a different understanding of their meanings

·         Controlled vocabularies serve five purposes:

·         Translation

·          Consistency

·         Indication of relationships

·         Label and browse

·         Retrieval

Types of Controlled Vocabularies

·         There are many types of controlled vocabularies are as followers….

·         Relationships in General

·         Subject Heading List

·         Controlled Lists

·         Synonym Ring Lists

·         Authority Files

·         Taxonomies

·         Alphanumeric Classification Schemes

·         Thesauri

·         Ontologies

·         Folksonomies

·         Relationships in General

·         In the context of this book, the term relationship means a state of connectedness or an association between two things in a database—in this case, fields or tables in a database for a controlled vocabulary.

             Subject Heading List

·         Subject headings, or simply headings, are uniform words or phrases intended to be assigned to books, articles, or other documents in order to describe the subject or topic of the texts and to group them with texts having similar subjects.

·         The most commonly used subject headings in libraries in the United States are the Library of Congress Subject Headings (LCSH), which form a comprehensive list of preferred terms or strings, often with cross-references.

·         Another well-known set of subject headings is the Medical Subject Headings (MeSH), which is used for indexing journal articles and books on medical science.

·         MeSH incorporates a thesaurus structure with subject headings.

·          Subject heading lists are typically arranged in alphabetical order, with cross-references between the preferred, no preferred, and other related headings.

           Controlled Lists

·         A controlled list is a simple list of terms used to control terminology.

·          In a well-constructed controlled list, the following is true: each term is unique;

·          terms are not overlapping in meaning;

·          terms are all members of the same class (i.e., having the same level of rank in a classification system);

·         Terms are equal in granularity or specificity, And terms are arranged alphabetically or in another logical order.

      

 Synonym Ring Lists

·         A synonym ring is a simple set of terms that are considered equivalent for the purpose of retrieval.

·          Equivalence relationships in most controlled vocabularies should be made only between terms and names that have genuine synonymy or identical meanings.

·          However, synonym rings are different.

·          Even though they are classified as controlled vocabularies.

·         They are almost always used in retrieval rather than indexing

 Authority Files

·         An authority file is a set of established names or headings and cross-references to the preferred form variant or alternate forms.

·         Common types of authority files are name authority files and subject heading authority files.

·         However, any listing of terms, names, or headings that distinguishes between a preferred term, name, or heading and alternate or variant names may be used as an authority.

·          In other words, almost any type of controlled vocabulary—with the exception of a synonym ring list—may be used as an authority.

Taxonomies

·         Taxonomy is an orderly classification for a defined domain.

·         It may also be known as a faceted vocabulary.

·         It comprises controlled vocabulary terms (generally only preferred terms) organized into a hierarchical structure.

·         Each term in Taxonomy is in one or more parent/child (broader/ narrower) relationships to other terms in the taxonomy.

·          There can be different types of parent/child relationships, such as whole/part, genus/ species, or instance relationships.

·         However, in good practice, all children of a given parent share the same type of relationship.

Alphanumeric Classification Schemes

·         Alphanumeric classification schemes are controlled codes (letters or numbers, or both letters and numbers) that represent concepts or headings.

·         They generally have an implied taxonomy that can be surmised from the codes.

·         Examples:

·         The Dewey Decimal Classification (DDC)

 Library of Congress Classification [LCC] system)

Thesauri

·         With additional features. A thesaurus is a semantic network of unique concepts, including relationships between synonyms, broader and narrower (parent/child) contexts, and other related concepts.

·         Thesauri may be monolingual or multilingual.

·         Thesauri may contain three types of relationships:

·         equivalence (synonym),

·          hierarchical (whole/ part, genus/species, or instance),

·          And associative.

·         Thesauri may also include additional peripheral.

·          A thesaurus combines the characteristics of synonym ring lists and taxonomies, together or explanatory information about a concept, including a definition (or scope note), bibliographic citations, and so on.

·          A thesaurus is more complex than a simple list, synonym ring list, or simple taxonomy.

·         Thesauri employ the versatile and powerful vocabulary control generally recommended for use as authorities in databases relating to art and cultural heritage.

Ontologies

·         Whereas the vocabularies discussed above are the ones most commonly used for art information, discussions of controlled vocabularies may also include Ontologies.

·          In common usage in computer science,

·          Ontology is a formal, machine-readable specification of a conceptual model in which concepts, properties, relationships, functions, constraints, and axioms are all explicitly defined.

·         Such ontology is not a controlled vocabulary, but it uses one or more controlled vocabularies for a defined domain and expresses the vocabulary in a representative language.

·          Ontologies generally divide the realm of knowledge.  They represent into the following areas: individuals, classes, attributes, relations, and event

Folksonomies

·         Folk sonomies is a new phrase referring to an assemblage of concepts represented by terms and names (called tags) that are compiled through social tagging.

·         Social tagging is the decentralized practice and method by which individuals and groups create, manage, and share tags (terms, names, etc.) to annotate and categorize digital resources in an online social environment.

·          This method is also referred to as social classification, social indexing, mob indexing, and folk categorization.

 Social tagging is not necessarily collaborative, because the effort is typically not organized; individuals are not actually working together or in concert, and standardization and common vocabulary are not employed