Chapter 4.2, Problem 84E

(a)

To determine

To explain what type of design did the investigators use in their study.

Answer to Problem 84E

The design is the matched pair design.

Explanation of Solution

In the question, a cardiologist wants to test whether the chocolates affected blood flow in the blood vessels or not. Thus we note that in the question each volunteer underwent two treatments and that is: bittersweet chocolate and a fake chocolate. Since each subjects undergoes two treatments the experiment conducted on the subjects by the researcher is a matched pair design experiment.

(b)

To determine

To explain why the investigators chose this design instead of a completely randomized design.

Explanation of Solution

In the question, a cardiologist wants to test whether the chocolates affected blood flow in the blood vessels or not. Thus, the investigators chose the matched pair design instead of a completely randomized design because a completely randomized design will result in two groups that are compared of which no subject will be in both groups and thus the groups will be different because each groups contains deferent subjects. The design chosen uses the same subjects for both groups which means that the results will be easier to compare for each treatment group as the groups are identical.

(c)

To determine

To explain why it is important to randomly assign the order of treatments for the subjects.

Explanation of Solution

In the question, a cardiologist wants to test whether the chocolates affected blood flow in the blood vessels or not. Thus, it is important to randomly assign the order of treatments for the subjects because if all subjects first receive the bittersweet chocolate then they might recognize that the second chocolate is fake. Thus, it is better that some receive the bittersweet chocolate first and that some receive the fake chocolate first.