The comparison distribution for a t test for independent means is a t distribution (as opposed to a normal curve)because:
A)tables are not available for the normal curve
B)the population variance is estimated
C)Z distributions were not used at the time the t test for independent means was invented
D)there are more degrees of freedom for a single sample than for when you use two samples

Question

Quizplus · Accepted Answer

The population variance is estimated in a t test for independent means, and therefore the t distribution is used instead of the normal curve. The estimated variance results in a slightly flatter and wider distribution, requiring a different type of distribution to accurately compare means.

The Comparison Distribution for a T Test for Independent Means