In: Statistics and Probability
A marketing research company is estimating the average total compensation of full-time waitstaff in the U.S. Data were randomly collected from 38 full-time waitstaff workers, and the 99% confidence interval for the mean was calculated to be $18,360<μ<$26,950$18,360<μ<$26,950. What would happen to the confidence interval if the confidence level were changed to 95%?
The 99% confidence interval for the mean was calculated to be $18,360<μ<$26,950, and the confidence interval is calculated a:
CI = M+/- E where M is the sample mean and E is the margin of error which is calculated as E = Zc* SE, where SE is the standard error and Zc is the critical standard score at a given confidence level, and the critical score decreases as the confidence level decreases, and the Margin of error as from formula can be computed that it is directly proportional to Zc so, the confidence interval width decreases as we change the confidence level from 99% to 95%.