Visualizing Categorical Data

Synonyms

Graphics for discrete data; Plots for qualitative information; Visual displays of nonnumerical data; Visualizing categorical data

Definition

Categorical data are data recorded about units on variables which take values in a discrete set of categories. Examples of categorical variables are gender, citizenship, or number of children. Categorical variables can be dichotomous (two categories; e.g., gender) or polytomous (more than two categories; e.g., citizenship), and nominal (unordered categories; e.g., gender) or ordinal (ordered categories; e.g., number of children). Categorical data can be in case form (individual raw data vector recorded about each unit) or frequency form (tabulated data counting over the categories of the variables), and univariate or multivariate (including bivariate). Quantitative variables can be discretized to become categorical variables (e.g., using child and adult instead of exact age). Strictly speaking, all data may be considered categorical...