Question: To examine the effect of pets in stressful situations, researchers recruited 45 women who said they were dog lovers. Fifteen of the subjects were randomly assigned to each of three groups to do a stressful task alone, with a good friend present, or with their dog present. (The stressful task was to count backwards by 13s or 17s.) The subject's mean heart rate during the task is one measure of the effect of stress. The Minitab ANOVA output for the data is given below.

a. Do the mean heart rates for the groups appear to show that the presence of a pet or a friend reduces heart rate during a stressful task?

b. What are the values of the ANOVA F-statistic and its p-value? What hypotheses does F test? Briefly describe the conclusions you draw from these data. Did you find anything surprising?