Which of the following statements is most nearly correct, other things being equal?
A)Using Student's t instead of z makes a confidence interval narrower.
B)The table values of z and t are about the same when the mean is large.
C)For a given confidence level, the z value is always smaller than the t value.
D)Student's t is rarely used, because it is more conservative to use z.

Question

Quizplus · Accepted Answer

For a given confidence level, the t-distribution has thicker tails than the normal distribution, which means that the critical value (t value) will be larger than the z value when the sample size is small and the population standard deviation is unknown. This accounts for the extra uncertainty in estimating the standard deviation from the sample.

Which of the Following Statements Is Most Nearly Correct, Other