Chapter 4.1, Problem 32E

To determine

To explain why the two means are so different.

Explanation of Solution

Marcos asked a random sample of $50$ mall shoppers for their weight. The groups were divided into half. The first half group were asked directly about the weight and the other half group were asked anonymously about the weight by “secret ballot”. Thus the mean of the anonymous group was higher than the group who were directly asked. This was so because the people does not want to tell the actual weight when they were asked directly due to their personal reasons. They do not want other to know their actual weight.

Thus, when they were asked directly there was biasness in the result of the survey as the responses were false. But when anonymously asked about the weight then they know that their identity will be kept secret so they gave true results in the survey. Therefore, they are different.