In
information science and
ontology, 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 bent, as classification can be applied over a wide
semantic spectrum.
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 metadata registry standard uses classification schemes as a way to classify administered items, such as
data elements, in a
metadata registry.
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
In
linguistics,
subordinate concepts are described as
hyponyms 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 (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 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 - 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 - 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.
*
ontology - an arrangement of concepts that are related by various well defined kinds of relations. The arrangement can be visualized in a
directed acyclic graph.
One example of a classification scheme for
data elements is a
representation term.
See also
*
ISO/IEC 11179
*
Faceted classification
*
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 ...
*
Ontology (computer science)
*
Representation class
*
Representation term
*
Simple Knowledge Organisation System
*
Semantic spectrum
References
{{reflist
External links
OECD Glossary of Statistical Terms - Classification SchemesISO/IEC 11179-2:2005 Metadata registries (MDR) - Part 2: ClassificationNancy Lawler's presentation on Classification Schemes
Metadata
Metadata registry
ISO/IEC 11179
Classification systems