information science Information science (also known as information studies) is an academic field which is primarily concerned with analysis, collection, Categorization, classification, manipulation, storage, information retrieval, retrieval, movement, dissemin ...

and

ontology In metaphysics, ontology is the philosophical study of being, as well as related concepts such as existence, becoming, and reality. Ontology addresses questions like how entities are grouped into categories and which of these entities exis ...

, a classification scheme is the product of arranging things into kinds of things (classes) or into ''groups'' of classes; this bears similarity to

categorization Categorization is the ability and activity of recognizing shared features or similarities between the elements of the experience of the world (such as Object (philosophy), objects, events, or ideas), organizing and classifying experience by a ...

, but with perhaps a more

theoretical A theory is a rational type of abstract thinking about a phenomenon, or the results of such thinking. The process of contemplative and rational thinking is often associated with such processes as observational study or research. Theories may be ...

bent, as classification can be applied over a wide

semantic spectrum The semantic spectrum (sometimes referred to as the ontology spectrum or the smart data continuum or semantic precision) is a series of increasingly precise or rather semantically expressive definitions for data elements in knowledge representat ...

. In the abstract, the resulting structures are a crucial aspect of

metadata Metadata is "data that provides information about other data", but not the content of the data, such as the text of a message or the image itself. There are many distinct types of metadata, including: * Descriptive metadata – the descriptive ...

, often represented as a hierarchical structure and accompanied by descriptive information of the classes or groups. Such a classification scheme is intended to be used for an arrangement or division of individual objects into the classes or groups, and the classes or groups are based on characteristics which the objects (members) have in common. The

ISO/IEC 11179 The ISO/IEC 11179 Metadata Registry (MDR) standard is an international ISO/IEC standard for representing metadata for an organization in a metadata registry. It documents the standardization and registration of metadata to make data understandabl ...

metadata registry standard uses classification schemes as a way to classify administered items, such as

data element In metadata, the term data element is an atomic unit of data that has precise meaning or precise semantics. A data element has: # An identification such as a data element name # A clear data element definition # One or more representation terms # ...

s, in a

metadata registry A metadata registry is a central location in an organization where metadata definitions are stored and maintained in a controlled method. A metadata repository is the database where metadata is stored. The registry also adds relationships with r ...

. Some quality criteria for classification schemes are: * Whether different kinds are grouped together. In other words, whether it is a grouping system or a pure classification system. In case of grouping, a subset (subgroup) does not have (inherit) all the characteristics of the superset, which makes that the knowledge and requirements about the superset are not applicable for the members of the subset. * Whether the classes have overlaps. * Whether subordinates (may) have multiple superordinates. Some classification schemes allow that a kind of thing has more than one superordinate others don't. Multiple supertypes for one subtype implies that the subordinate has the combined characteristics of all its superordinates. This is called multiple inheritance (of characteristics from multiple superordinates to their subordinates). * Whether the criteria for belonging to a class or group are well defined. * Whether the kinds of relations between the concepts are made explicit and well defined. * Whether subtype-supertype relations are distinguished from composition relations (part-whole relations) and from object-role relations.

In linguistics

linguistics Linguistics is the scientific study of human language. It is called a scientific study because it entails a comprehensive, systematic, objective, and precise analysis of all aspects of language, particularly its nature and structure. Linguis ...

subordinate A hierarchy (from Greek: , from , 'president of sacred rites') is an arrangement of items (objects, names, values, categories, etc.) that are represented as being "above", "below", or "at the same level as" one another. Hierarchy is an important ...

concepts are described as

hyponym In linguistics, semantics, general semantics, and ontologies, hyponymy () is a semantic relation between a hyponym denoting a subtype and a hypernym or hyperonym (sometimes called umbrella term or blanket term) denoting a supertype. In other ...

s of their respective superordinates; typically, a hyponym is 'a kind of' its superordinate.Keith Allan (2002, p. 260), Natural Language Semantics, Blackwell Publishers Ltd, Oxford, .

Benefits of using classification schemes

Using one or more classification schemes for the classification of a collection of objects has many benefits. Some of these include: * It allows a user to find an individual object quickly on the basis of its kind or group. * It makes it easier to detect duplicate objects. * It conveys

semantics Semantics (from grc, σημαντικός ''sēmantikós'', "significant") is the study of reference, meaning, or truth. The term can be used to refer to subfields of several distinct disciplines, including philosophy Philosophy (f ...

(meaning) of an object from the definition of its kind, which meaning is not conveyed by the name of the individual object or its way of spelling. * Knowledge and requirements about a kind of thing can be applied to other objects of that kind.

Kinds of classification schemes

The following are examples of different kinds of classification schemes. This list is in approximate order from informal to more formal: *

thesaurus A thesaurus (plural ''thesauri'' or ''thesauruses'') or synonym dictionary is a reference work for finding synonyms and sometimes antonyms of words. They are often used by writers to help find the best word to express an idea: Synonym diction ...

- a collection of categorized concepts, denoted by words or phrases, that are related to each other by narrower term, wider term and related term relations. *

taxonomy Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...

- a formal list of concepts, denoted by controlled words or phrases, arranged from abstract to specific, related by subtype-supertype relations or by superset-subset relations. *

data model A data model is an abstract model that organizes elements of data and standardizes how they relate to one another and to the properties of real-world entities. For instance, a data model may specify that the data element representing a car be co ...

- an arrangement of concepts (entity types), denoted by words or phrases, that have various kinds of relationships. Typically, but not necessarily, representing requirements and capabilities for a specific scope (application area). *

network (mathematics) In discrete mathematics, and more specifically in graph theory, a graph is a structure amounting to a set of objects in which some pairs of the objects are in some sense "related". The objects correspond to mathematical abstractions called '' ...

- an arrangement of objects in a random graph. *

- an arrangement of concepts that are related by various well defined kinds of relations. The arrangement can be visualized in a

directed acyclic graph In mathematics, particularly graph theory, and computer science, a directed acyclic graph (DAG) is a directed graph with no directed cycles. That is, it consists of vertices and edges (also called ''arcs''), with each edge directed from one ve ...

. One example of a classification scheme for

s is a

representation term A representation term is a word, or a combination of words, that semantically represent the data type (value domain) of a data element. A representation term is commonly referred to as a ''class word'' by those familiar with data dictionaries. ISO ...

References

{{reflist

External links

OECD Glossary of Statistical Terms - Classification Schemes

ISO/IEC 11179-2:2005 Metadata registries (MDR) - Part 2: Classification

Nancy Lawler's presentation on Classification Schemes
Metadata Metadata registry ISO/IEC 11179 Classification systems

In linguistics

Benefits of using classification schemes

Kinds of classification schemes

See also

References

External links