(a) Simple random sampling A. guarantees valid results. B. reduces bias resulting from the behavior of the interviewer. C. reduces bias resulting from poorly worded questions. D. offsets bias resulting from undercoverage and nonresponse. E. None of the above.
(b) A news release for a diet product company reports: There's good news for the 65 million Americans currently on a diet. Its study showed that people who lose weight can keep it off. The sample was 20 graduates of the company's program who endorse it in commercials. The results of the sample are probably A. biased, understating the effectiveness of the diet. B. biased, overstating the effectiveness of the diet. C. unbiased, but they could be more accurate. A larger sample size should be used. D. None of the above.
You can earn partial credit on this problem.