How to do it...

We proceed with the recipe as follows:

1. Use an if statement to check and install the car package:

> if(!require(car)){ install.packages('car') }

1. Load the package and use ? to call for data set documentation:

> library(car)
> ?Salaries

1. Check both the first row and the data set object type:

> head(Salaries)
> class(Salaries)