Chapter 4.2, Problem 79E

(a)

To determine

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

Answer to Problem 79E

Matched pair design.

Explanation of Solution

In this study, the researcher wants to study does talking on a hands free cell phone distract drivers or not. For, this experiment they examined forty students and both of the experiments are conducted on each of the students.

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 wants to study does talking on a hands free cell phone distract drivers or not. For, this experiment they examined forty students and both of the experiments are conducted on each of the students. And the design used is matched pair design.

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.

(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 wants to study does talking on a hands free cell phone distract drivers or not. For, this experiment they examined forty students and both of the experiments are conducted on each of the students.

It is important to randomly assign the order of the treatments because we could expect the subjects to perform better on their second attempt as they would have more experienced. Thus we could expect the experience to be a possible confounding variable.

If we would then randomly assign the order of the treatments then both treatments will occur as the first attempt of some subjects and second attempts of other subjects which means that we could compare the results of the two treatments while knowing that the experience would affect the differences between the two attempts differing.

(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 variables in this experiment. The stimulator, route, driving conditions and traffic flow were all kept the same for both the sessions. This how the researchers controlled the other variables so as to prevent these variables from adding variability to the response variable.