Introduction to Statistics - Categorical Data

Counts

Counting up the # of cases in each category

Proportions

Divide the # of cases per category by sample size

Percentages

The proportion multiplies by 100

Frequency table

Numeric display of the categories and the counts

Relative frequency table

Numeric display of the categories and the proportions

Bar Chart

A graphical display of a categorical variable’s distribution

Response Variable

The main variable of interest

Explanatory variable

The variable used to “explain” / predict the difference in distribution of the response variable

Association

When the distribution of the response variable is different for the different categories of the explanatory variable

Contingency Table

Numeric display of the relationship between two categorical variables

Mosiac Plot

Graphical display of the relationship between two categorical variables

Marginal Distribution

The distribution for each variable separately, ignoring the other variable

Conditional Distribution

Looks at the counts or proportions for one variable contingent upon a particular category of another variable