Exercise

# 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.

Instructions 1/3

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3

## Question

Which of the below sentences about the Q-Q plot is true?

### Possible answers

A point on the plot corresponds to one of the quantiles of the second distribution plotted against the same quantile of the first distribution.

A Q-Q plot is a graphical method for comparing two probability distributions by plotting their quantiles against each other.

If the two distributions being compared are similar, the points will approximately lie on the line.

All of the above answers are true.