Topaz Research is planning to sample area television viewers in order to estimate the proportion of all TV sets that were tuned to Channel 4 to watch the latest NBC miniseries.
a. If the company intends to produce a 95% confidence interval that will be no wider than 4 percentage points (.04), how large a simple random sample would you recommend? (The results of a small “pilot” study showed a sample proportion of .12.)
b. How large a sample would be required for a 90% interval of the same width?
c. Suppose no pilot study results were available. Recompute the recommended sample sizes for parts a and b.