Q-Q plot

During the interview, you can use a Q-Q plot to support the result of the Shapiro-Wilk test.

A Q-Q plot that compares a certain sample data against the values of a normal distribution helps to assess the normality of the sample visually.

Recall that:

• qqplot(x, y) - produces a Q-Q plot of two datasets,
• qqnorm(x) - produces a Q-Q plot against normal distribution.

The line added by qqline(x) is by default normal.

The cats dataset from the MASS package is available for this exercise.