Which is true about a 99% confidence interval based on a given sample? I. The interval contains 99% of the population.
II) Results from 99% of all samples will lie in this interval.
III) The interval is wider than a 95% confidence interval would be.
A) None
B) I only
C) II only
D) III only
E) I and III

Question

Quizplus · Accepted Answer

III is correct because a 99% confidence interval is wider than a 95% confidence interval to account for the increased certainty of including the true population parameter. I is incorrect because the interval does not contain 99% of the population but rather is an interval that we are 99% confident contains the true population parameter. II is incorrect because it misinterprets the concept; it's not that 99% of all samples will fall within this specific interval, but that 99% of such intervals constructed from repeated sampling would contain the true population parameter.

Which Is True About a 99% Confidence Interval Based on a Given