Chapter 5.1, Problem 5.4E

(a)

To determine

To explain why we think the results of the two studies are so different.

Explanation of Solution

We think the results of the two studies are so different because the first study used a voluntary response sample and thus the participants has to be willing to answer the question (truthfully) and those that did not wash their hands were probably less willing to admit this.

(b)

To determine

To explain why these precautions were taken by the observers.

Explanation of Solution

These precautions were taking such that the observers did not influence the participants to wash their hands.