33. “900” Numbers Radio and television stations often air controversial issues during broadcast time. A poll is then conducted, asking viewers who agree with the issue to call a certain 900 telephone number and those who disagree to call a second 900 telephone number.

All respondents pay a fee for their calls.

a. Does this polling technique result in a random sample?

b. What can be said about the validity of the results of such a survey? Do you need to worry about a margin of error in this case?