Power is the ability to: (A) Reject true null hypothesis, (B) Reject false null hypothesis, (C) Accept true null hypothesis, (D) Accept false null hypothesis
Answer is B. Power is the probability of rejecting the null hypothesis when, in fact, it is false. Power is the probability of making a correct decision (to reject the null hypothesis) when the null hypothesis is false. Power is the probability that a test of significance will pick up on an effect that is present. Ref :