If statistical power is .80, then the probability of a Type II error is:
A)0.80
B)1.80
C)0.20
D)0.60

Question

Quizplus · Accepted Answer

Statistical power is the probability of rejecting a null hypothesis when it is false (aka correctly detecting a true effect). Therefore, if statistical power is .80, then the probability of a Type II error (failing to reject a false null hypothesis) is the complement of the statistical power, which is 1 - .80 = .20. So, the best choice is C, with the explanation that statistical power and the probability of Type II error are complementary probabilities.

If Statistical Power Is