Nominal Variable: A nominal variable is a type of categorical variable where the categories have no inherent order or ranking, such as gender (male, female) or race (Caucasian, African American, Asian).
Ordinal Variable: An ordinal variable is a type of categorical variable where the categories have a natural order or ranking, such as education level (elementary, high school, college) or customer satisfaction (poor, average, good, excellent).
Dichotomous Variable: A dichotomous variable is a special case of a categorical variable that can take on only two possible values, such as yes/no, pass/fail, or alive/dead.