Question

How large the size of a sample needs to be if we want to a 90% confidence level with a margin of error no more than 1.5%

Answer 1

A 90 percent level can be obtained with a smaller sample, which usually translates into a less expensive survey. To obtain a 3 percent margin of error at a 90 percent level of confidence requires a sample size of about 750. For a 95 percent level of confidence, the sample size would be about 1,000.