Suppose a 95% confidence interval for μ turns out to be (1,000,2,100).To make more useful inferences from the data,it is desired to reduce the width of the confidence interval.Which of the following will result in a reduced interval width?
A)Increase the sample size.
B)Increase the confidence level.
C)Increase the population mean.
D)Increase the sample mean.

Question

Quizplus · Accepted Answer

Increasing the sample size will reduce the width of the confidence interval because the standard error (which determines the width of the interval) decreases as the sample size increases. Increasing the confidence level will actually increase the width of the interval because there is a tradeoff between confidence and precision. Increasing the population mean or sample mean will have no effect on the width of the interval. Therefore, the best choice is A.

Suppose a 95% Confidence Interval for μ Turns Out to Be