Chapter 4.2, Problem 80E

(a)

To determine

To find out what type of design did the researchers use in their study.

Answer to Problem 80E

Matched pair design.

Explanation of Solution

In this study, the researcher wanted to test if chocolate affects blood vessel function or not. So, they recruited healthy young volunteers to examine this and each of the volunteers goes through both of the treatments i.e. they were give both bittersweet chocolate and the fake chocolate.

Thus we can say that, the design used for this experiment is matched pair design, since each subject is administered both treatments in a random order and compared to themselves.

(b)

To determine

To explain why the researcher choose this design instead of completely randomized design.

Explanation of Solution

In this study, the researcher wanted to test if chocolate affects blood vessel function or not. So, they recruited healthy young volunteers to examine this and each of the volunteers goes through both of the treatments i.e. they were give both bittersweet chocolate and the fake chocolate.

The researcher choose matched pair design instead of completely randomized design because matched pair design helps eliminate variability among subjects by comparing each subject's response to treatment A with their own response to treatment B.

Thus, this design uses the same subjects for both groups which means that the result will be easier to compare.

(c)

To determine

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

Explanation of Solution

In this study, the researcher wanted to test if chocolate affects blood vessel function or not. So, they recruited healthy young volunteers to examine this and each of the volunteers goes through both of the treatments i.e. they were give both bittersweet chocolate and the fake chocolate.

It is important to randomly assign the order of the treatments because if all the subjects first receive the bittersweet chocolate then they might recognize that the second chocolate is fake. Thus, it is better to receive the bittersweet chocolate first and that some receive the fake chocolate first.

(d)

To determine

To explain how and why the researchers controlled for other variables in this experiment.

Explanation of Solution

The researchers controlled for other potential health issues by choosing young, healthy volunteers. They also controlled against chocolate consumption outside of the confines of the experiment.

Other potential health issues were controlled because other health issues may be responsible in differences between blood vessel function as opposed to chocolate. Additionally, outside chocolate consumption was controlled to ensure that a placebo subject did not have real chocolate and skew the results of the experiment.