Chapter 13, Problem 31E

a)

To determine

To explain the importance of randomization.

Answer to Problem 31E

Randomization is important to equalize two groups.

Explanation of Solution

There might be bias in the results or in the subjects. Therefore, to reduce this bias and equalize two treatments with respect to unknown factor we need randomization.

b)

To determine

To explain the importance of including a control group.

Explanation of Solution

A control group could have revealed whether either exercise program was better or worse than just letting the injury heal without exercise. Therefore, it helps to make natural variations in the healing time.

c)

To determine

To explain the use of blinding.

Answer to Problem 31E

Doctors should be unaware of the received treatment to the athletes.

Explanation of Solution

Blinding accomplished by making the doctors who evaluated the athletes to approve their return to sports should not know which treatment the athletes received. That means, Doctors should be unaware of the received treatment to the athletes.

d)

To determine

To explain whether the difference is statistically significant.

Answer to Problem 31E

The difference is not statistically significant.

Explanation of Solution

The difference between means is less as compare to difference in standard deviations. Therefore, the variability in the times is higher. That means, the difference is likely to occur by chance. Hence, the difference is not statistically significant.