The t test for two independent samples may only be used when
A) the selection of subjects for the first group does not depend in any way on the selection of subjects for the second group
B) the subjects used in the two samples are matched on some relevant variable
C) the same subjects are used twice
D) the degrees of freedom are independent of the sample sizes

Question

Quizplus · Accepted Answer

The t test for two independent samples is only appropriate when the two groups of subjects are independent of each other, meaning that the selection of subjects for the first group does not depend on the selection of subjects for the second group. If the two groups are not independent, then a paired t test or other statistical method must be used. Therefore, option A is the correct choice.

The T Test for Two Independent Samples May Only Be