Influence? Your scatterplot in Exercise 10.38 shows one unusual point: Student 3, who drank 9 beers.

(a) Does Student 3 have the largest residual from the fitted line?

(You can use the scatterplot to see this.) Is this observation extreme in the x direction, so that it may be influential?

(b) Do the regression again, omitting Student 3. Add the new regression line to your scatterplot. Does removing this observation greatly change predicted BAC? Does r 2 change greatly? Does the P-value of your test change greatly? What do you conclude:

did your work in the previous problem depend heavily on this one student?