If the expected direction of an effect is correct, then using a one-tailed hypothesis test instead of a two-tailed hypothesis test:
A) increases power.
B) decreases power.
C) makes power 1.0.
D) makes power 0.

Question

Quizplus · Accepted Answer

Using a one-tailed hypothesis test instead of a two-tailed hypothesis test increases the power of the test as all of the alpha level is being allocated to one tail instead of being split between two tails. This reduces the probability of a type II error and increases the likelihood of detecting a true effect. However, it is important to note that using a one-tailed test is only appropriate if there is strong theoretical or empirical evidence indicating the direction of the effect.

If the Expected Direction of an Effect Is Correct, Then