A one-tailed test is proper when
A) you do not have enough data for a two-tailed test
B) you have only one sample, not two
C) you are only interested in finding out if the effect of a treatment is to increase the scores
D) you want to make the standard error of a difference as small as possible.

Question

Quizplus · Accepted Answer

A one-tailed test is appropriate when the research hypothesis specifies a direction of the effect, such as predicting that a treatment will increase scores, not just change them.

A One-Tailed Test Is Proper When