What effect will using a one-tailed test over a two-tailed test have on power (presuming the true population difference is in the expected direction)?
A)it will increase power
B)it will have no effect on power
C)it will decrease power
D)power cannot be calculated if a one-tailed test is used

Question

Quizplus · Accepted Answer

Using a one-tailed test over a two-tailed test will increase power because all of the α level is concentrated on one tail instead of being split between both tails. This means that less extreme observations will be more likely to fall into the critical region, leading to a higher chance of rejecting the null hypothesis.

What Effect Will Using a One-Tailed Test Over a Two-Tailed