Chapter 6.1, Problem 6.26E

(a)

To determine

To explain how the three principles of experimental design were addressed in the study.

Explanation of Solution

Replication: each of the treatments is replicated $80$ times, with each subject counting as a replication.

Randomization: the study says that the subjects were randomly assigned to the two treatments.

Local control: There were multiple treatments, improving the quality of the experiment.

(b)

To determine

To explain the meaning of the sentence given in the question.

Explanation of Solution

This means that the difference in the number of women who were pregnant between the two treatments did not occur because of chance.

(c)

To determine

To explain why can’t we conclude that acupuncture caused the difference in pregnancy rates.

Explanation of Solution

We cannot say that acupuncture caused the increase in pregnancy rates because there may be confounding variables in this study.