Chapter 4.2, Problem 83E

(a)

To determine

To find out what kind of design is this given in the figure in the question.

Answer to Problem 83E

It is a completely randomized design.

Explanation of Solution

In the question, researchers want to find out does talking on the hands-free cell phone distract drivers. Thus, researchers are considering the design shown in the figure given in the question. The design given is a completely randomized design because it randomly splits the main group into two smaller groups. One group receives one treatment (Driving) and the other group receives the other treatment (Driving and Talking). /the results (Brake Time) are compared afterward.

(b)

To determine

To explain how blocking could be used to improve the design in part (a).

Explanation of Solution

In the question, researchers want to find out does talking on the hands-free cell phone distract drivers. Thus, blocking can be used to improve the design in part (a) by let us have each student be a block and run the simulator twice, once with the phone and once without, in random order, as in a matched pairs design. This will control variability in driving ability among individual students. Thus, by this it can help to improve the design.

(c)

To determine

To explain why it is important to randomly assign the treatments within each block.

Explanation of Solution

In the question, researchers want to find out does talking on the hands-free cell phone distract drivers. Thus, it is important to randomly assign the treatments within each block because we would expect the subjects to perform better on their second attempt as they would have more experience. Thus, we could expect the experience to be a possible confounding variable. If we would then randomly assign the order of treatments then both treatments will occur as the first attempt for some subjects and the second attempt for 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.