R: Mining Spatial, Text, Web, and Social Media Data

Contingency tables, bivariate statistics, and checking for data normality

Contingency tables are frequency tables represented by two or more categorical variables along with the proportion of each class represented as a group. Frequency table is used to represent one categorical variable; however, contingency table is used to represent two categorical variables.

Let's see an example to understand contingency tables, bivariate statistics, and data normality using the Cars93 dataset:

> table(Cars93$Type)

Compact Large Midsize Small Sporty Van

16 11 22 21 14 9

> table(Cars93$AirBags)

Driver & Passenger Driver only None

16 43 34

The individual frequency table for two categorical variables AirBags and Type of the car is represented previously: ...