1) Why do we have to compute a pooled variance for an independent-sample t-test?

Group of answer choices

A. Because the degrees of freedom for this test is 0

B. Because we need to get a good estimate of the weighted average of the variances

C. Because we know that the 2 variances are equal

D. Because the groups that we're studying are related.

2)What does a difference score of 0 represent?

Group of answer choices

A. That the statistician made a calculation error.

B. That there were no participants in the study.

C. That there was no change between the before and after scores.

D. That there was no change in the t-test number.