Data for Example 2.6

`Ratings`

A data frame/tibble with 250 observations on two variables

- rating
character variable with students' ratings of instructor (A-F)

- gpa
students' grade point average

Kitchens, L. J. (2003) *Basic Statistics and Data Analysis*.
Pacific Grove, CA: Brooks/Cole, a division of Thomson Learning.

```
boxplot(gpa ~ rating, data = Ratings, xlab = "Student rating of instructor",
ylab = "Student GPA")
if (FALSE) {
library(ggplot2)
ggplot2::ggplot(data = Ratings, aes(x = rating, y = gpa, fill = rating)) +
geom_boxplot() +
theme_bw() +
theme(legend.position = "none") +
labs(x = "Student rating of instructor", y = "Student GPA")
}
```