What advertising medium is most influential in making a purchase decision? According to a TVB survey, 37.2% of American adults point to TV. (Data extracted from "TV Seen Most Influential Ad Medium for Purchase Decisions," MC Marketing Charts, June 18, 2012.)
a. To conduct a follow up study that would provide 95% confidence that the point estimate is correct to within ±0.04 of the population proportion, how large a sample size is required?
b. To conduct a follow up study that would provide 99% confidence that the point estimate is correct to within ±0.04 of the population proportion, how many people need to be sampled?
c. To conduct a follow up study that would provide 95% confidence that the point estimate is correct to within ±0.02 of the population proportion, how large a sample size is required?
d. To conduct a follow up study that would provide 99% confidence that the point estimate is correct to within ±0.02 of the population proportion, how many people need to be sampled?
e. Discuss the effects on sample size requirements of changing the desired confidence level and the acceptable sampling error.