You are the assistant director of political research for the ABC television network, and two candidates, Joseph Thomas and Ann Martin, are running for president of the United States. You need to furnish a prediction of the percentage of the vote going to Martin, assuming the election was held today, for tomorrow's evening newscast. You want to be 95 percent confident in your prediction and desire a total precision of 6 percent.
a. Assume that you have no reliable information concerning the percentage of the population that prefers Martin. What sample size will you use for the project?
b. Assume that a similar poll, taken thirty days ago, revealed that 40 percent of the respondents would vote for Martin. Taking this information into account, what sample size will you use for the project?
c. Which of the two sample sizes you have just calculated would you prefer to use for your study? Why?