In each of the following situations, summarize negative aspects of the sample design.
a. A newspaper asks readers to vote at its Internet site to determine if they believe government expenditures should be reduced by cutting social programs. Based on 1434 votes, the newspaper reports that 93% of the city’s residents believe that social programs should be reduced.
b. A congresswoman reports that letters to her office are running 3 to 1 in opposition to the passage of stricter gun control laws. She concludes that approximately 75% of her constituents oppose stricter gun control laws.
c. An anthropology professor wants to compare attitudes toward premarital sex of physical science majors and social science majors. She administers a questionnaire to her Anthropology 437, Comparative Human Sexuality class. She finds no appreciable difference in attitudes between the two majors, so she concludes that the two student groups are about the same in their views about premarital sex.
d. A questionnaire is mailed to a simple random sample of 500 household addresses in a city. Ten are returned as bad addresses, 63 are returned completed, and the rest are not returned. The researcher analyzes the 63 cases and reports that they represent a “simple random sample of city households.”