Chapter 4.1, Problem 8E

a.

To determine

To find out the type of sample that the parade survey obtain.

Explanation of Solution

This is an online poll where it depends on readers whether they vote or not. Hence, it is a voluntary response sample. In voluntary response samples, people decide whether to join the sample in response to an open invitation.

b.

To determine

To explain why the sampling method is biased.

Explanation of Solution

Since it is a voluntary response sample, it is biased toward readers who feel most strongly about the issue. In voluntary response samples, in which people decide whether to join the sample in response to an open invitation, are almost guaranteed to show bias. Voluntary response samples attract people who feel strongly about the issue in question, that leads bias. Hence, 85% is probably higher than the true percent because it is likely that readers who feel most strongly about this issue have in some way been involved in an accident caused by cell phone use while driving.