Chapter 13, Problem 44E

a)

To determine

To explain why this does not necessarily prove that the special course caused the scores to go up.

Explanation of Solution

If we want to prove causation, then we need a well-controlled experiment, because it tries to eliminate the effect of any lurking variables. As students were not randomly assigned to the special study course. Those who signed up for the course may be a special group whose scores would have improved anyway due to other factors.

b)

To determine

To explain the design for an experiment that could test the effectiveness of the tutorial course.

Explanation of Solution

First need to take volunteers for the SAT. Then assign the subjects randomly to the study course or no study course. After giving the study course to the corresponding group, have both groups take the SAT again. Finally, compare the score of both groups.

c)

To determine

To explain the how the proposed design.

Explanation of Solution

First need to block the students by exam score after taking the SAT. Therefore, the students with the lowest SAT scores belong to block 1 and the students with the highest SAT scores belong to block 2