Question

Online polls Parade magazine posed the following question: “Should drivers be banned

from using all cell phones?” Readers were encouraged to vote online at parade.com. The

subsequent issue of Parade reported the results:$2407(85\%)$said “Yes” and $410(15\%)$

said “No.”

a. What type of sample did the Parade survey obtain?

b. Explain why this sampling method is biased. Is $85\%$probably greater than or less than

the true percent of all adults who believe that all cell phone use while driving should be

banned? Why?

Short answer

a) The subjects can decide whether or not they want to be included in the sample.The sample is a voluntary response sample

b) They have data about the strongest opinions, resulting because persons with the strongest opinions choose to engage in a voluntary response sample.

Step-by-step solution

Part (a) Step 1: Given information

We have to tell about type of sample did the counsellor obtain.

Part (a) Step 2: Explanation

We note that the sample in the exercise prompt is a voluntary response sample. The sample is a voluntary response sample because the subjects must choose whether or not to call the telephone number (if they do, they will be included in the sample), and thus the subjects can decide whether or not they want to be included in the sample.

Part (b) Step 1: Given information 

We have to tell about true percent of all adults who believe that all cell phone use while driving

Part (b) Step 2: Explanation

Because persons with the strongest opinions choose to engage in a voluntary response sample, we will only have data about the strongest opinions, resulting in us continuously overestimating or underestimating the actual opinions.