Definition:Categorical Variable

Definition

A categorical variable is a random variable whose values are categories.

Let $X$ be a random variable whose values take on the classification of side effects of a drug:

$\set {\text {none}, \text {slight}, \text {moderate}, \text {severe} }$

Then $X$ is classed as a categorical variable.

Let $X$ be a random variable whose values take on various classifications of personal character:

$\set {\text {introvert}, \text {extrovert}, \ldots{} }$

Then $X$ is classed as a categorical variable.

Let $X$ be a random variable whose values take on various classifications of time to failure of a machine part:

$\set {< 100 \, \mathrm {hr}, 100 - 199 \, \mathrm {hr}, 200 - 299 \, \mathrm {hr}, > 300 \, \mathrm {hr} }$

Then $X$ is classed as a categorical variable.

Let $X$ be a random variable whose values take on various classifications of marital status:

$\set {\text {single}, \text {married}, \text {widowed}, \text {divorced} }$

Then $X$ is classed as a categorical variable.