15. A study is conducted to determine whether dieting plus exercise is more effective in producing weight loss than dieting alone. Twelve pairs of matched subjects are run in the study. Subjects are matched on initial weight, initial level of exercise, age, and gender. One member of each pair is put on a diet for 3 months. The other member receives the same diet but, in addition, is put on a moderate exercise regimen.

The following scores indicate the weight loss in pounds over the 3-month period for each subject:

to measure its activity level. The open-fi eld apparatus is composed of a fairly large platform with sides around it to prevent the animal from leaving the platform. A grid confi guration is painted on the surface of the platform such that the entire surface is covered with squares. To measure activity, the experimenter merely counts the number of squares that the animal has crossed during a fi xed period of time. In the present experiment, each rat is tested in the open-fi eld apparatus for 10 minutes.

The results are shown in the table; the scores are the number of squares crossed per minute.

a. What is the overall null hypothesis?

b. Using 0.05, what do you conclude?

c. What is the size of the effect, using vˆ2?

d. Evaluate the a priori hypothesis that a high amount of exogenous thyroxin produces an effect on activity different from that of saline. Use
0.052 tail.

e. Use the Tukey HSD test with 0.05 to compare all possible pairs of means. What do you conclude?
biological

Amount of Thyroxin Zero Low 1 2 Moderate High 3 2 4 00 3 3 7 4 12 10 3 5 9 8 252 2 5 5 3 2 1 3 4 5 4 24364 2 7841000 La 6 7 5 9 13 9 11 8 7 4 9