Categorical Variable in statistics is a variable that can take on one of a limited, and usually fixed number of possible values, assigning each unit of observation to a particular group or nominal category on the basis of some qualitative property. In computer science and some branches of mathematics, categorical variables are referred to as enumerations or enumerated types. Commonly, each of the possible values of a categorical variable is referred to as a level. The probability distribution associated with a random categorical variable is called a categorical distribution. Categorical data is the statistical data type consisting of categorical variables or of data that has been converted into that form, for example as grouped data. A categorical variable that can take on exactly two values is termed a binary variable or dichotomous variable an important special case is the Bernoulli variable. Categorical variables with more than two possible values are called polytomous variables, categorical variables are often assumed to be polytomous unless otherwise specified.
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