14.22 Multiple comparison for time on Facebook Refer to Exercise 14.13, which investigated the amount of time freshman, sophomores, juniors, and seniors spent on Facebook while doing schoolwork. The data from the study are available on the book’s website, where time is measured in minutes.

a. If you want to construct confidence intervals between all possible pairs of means for the four classes, how many intervals do you need to construct?

b. Using software (such as the web app ANOVA accessible from the book’s website), find the confidence intervals for all possible pairs of population means such that the overall error rate of all intervals is 0.05 (use Tukey’s method). Visualize the confidence intervals in a figure similar to Figure 14.4. (The web app can construct such a plot, which you can download.)

c. Is it true that seniors spent significantly less time than all other classes? Explain.