At a given significance level, a one-tailed test:
A) is less likely to detect real differences between means than is a two-tailed test.
B) has a higher critical value than does a two-tailed test.
C) is less accurate than a two-tailed test.
D) is more likely to detect real differences between means than is a two-tailed test, given that the correct tail was selected for the test.

Question

Quizplus · Accepted Answer

A one-tailed test is more powerful than a two-tailed test in detecting a real difference in the specified direction because it allocates all the significance level to one tail, making it more likely to reject the null hypothesis if the effect is in the predicted direction.

At a Given Significance Level, a One-Tailed Test