Categorical variables and data can be either nominal or ordinal. Examples of nominal categorical variables are gender, region of residence, field of study, type of transport, type of housing, etc. There i­s no orderi­ng i­n the categori­es of these variables. . Exam grade is an ordinal categorical variable, since its categories are ordered: A is better than a B, B is better than a C, and so on. Other examples of ordinal categorical variables are ­income group (I­f i­ncomes have been categorized), an attitude question in a survey where possible responses are strongly agree/agree/disagree/strongly disagree (these categories have an order).