Dogs, friends, and stress. In Exercise 29.3, the ANOVA F test had a very small P-value, giving good reason to conclude that mean heart rates under stress do differ depending on whether a pet, a friend, or no one is present. Do the means for the two treatments (pet, friend) differ significantly from each other and from the mean for the control group?

(a) What are the three null hypotheses that formulate these questions?

(b) We want to be 90% confident that we don't wrongly reject any of the three null hypotheses. Tukey pairwise comparisons can give conclusions that meet this condition. What are the conclusions?

Exercise 29.3:

Dogs, friends, and stress. If you are a dog lover, perhaps having your dog along reduces the effect of stress. To examine the effect of pets in stressful situations, researchers recruited 45 women who said they were dog lovers. The EESEE story "Stress among Pets and Friends" describes the results. Fifteen of the subjects were randomly assigned to each of three groups to do a stressful task alone (the control group), with a good friend present, or with their dog present. The subject's mean heart rate during the task is one measure of the effect of stress. Table 29.2 displays

the data. Are there significant differences among the mean heart rates under the three conditions?