What is an Attribute?

An attribute is a data field, defining a characteristic of a data object. The nouns attribute, dimension, feature, and variable are used correspondently in the literature. The dimension is generally used in data warehousing. Machine learning literature influence to use the term feature, while statisticians prefer the method svariable.

Data mining and database experts generally use the term attribute. Attributes defining a user object can include, for instance, customer ID, name, and address. Observed values for a given attribute are referred to as observations.

A set of attributes can define a given object is known as attribute vector (or feature vector). The distribution of data containing one attribute (or variable) is known as univariate. A bivariate distribution contains two attributes, etc.

The type of an attribute is decided by the set of possible values including nominal, binary, ordinal, or statistical attribute can have.

Nominal Attributes − Nominal defines associating with names. The values of a nominal attribute are symbols or names of things. Each value defines some type of category, code, or state, etc. Nominal attributes are defined as categorical. The values do not have any significant order. In computer science, the values are also called an enumerations.

Binary Attributes − A binary attribute is a nominal attribute with only two elements or states such as 0 or 1, where 0 generally defines that the attribute is absent, and 1 defines that it is present. Binary attributes are defined as Boolean if the two states equivalent to true and false.

A binary attribute is symmetric if both of its states are same valuable and produce the same weight. There is no preference on which results must be coded as 0 or 1. An example can be the attribute gender having the states male and female.

A binary attribute is asymmetric if the results of the states are not similarly important, including the positive and negative results of a medical test for HIV. By convention, it can code the most essential result, which is generally the nearest one, by 1 (e.g., HIV positive) and the different by 0 (e.g., HIV negative).

Ordinal Attributes − An ordinal attribute is an attribute with possible values that have a significant order or ranking between them, but the magnitude among successive values is not known.

Numeric Attributes − A numeric attribute is quantitative. It is a measurable quantity, defined in integer or real values. It can be interval-scaled or ratio-scaled.