PLEASE NO COPYPASTE 1 Assume that you read a study reporting

PLEASE NO COPY&PASTE

1) Assume that you read a study reporting a significant result for a Null Hypothesis Significance Test.

A) Do you need to know the power of the experiment to figure out the probability that the alternative hypothesis is true?

B) Explain why power does or does not affect the probability that the alternative hypothesis is true using concepts from Bayes Theorem. (Make sure to clearly define power as part of your explanation).

C) Do you need to know the alpha value used by the authors of the study to figure out the probability that the alternative hypothesis is true? D) Explain why alpha does or does not affect the probability that the alternative hypothesis is true using concepts from Bayes Theorem. (Make sure to clearly define alpha as part of your explanation).

Solution

A) No. We do not need to know the power of the experiment to figure out the probability that the alternative hypothesis is true. It is the probability of rejecting a false null hypothesis.

B) Power does not affect the probability that the alternative hypothesis is true because it is the probability that we reject H₀ when it is false. It gives the probability that our test can detect an effect. We do not test for the alternative hypothesis, we test for the null hypothesis and accept or reject it. It does not not prove alternative hypothesis.

C) Yes. We need to know the alpha value used by the authors of the study to figure out the probability that the alternative hypothesis is true. It is probability of rejecting a true null hypothesis.

D) Alpha affects the probability that the alternative hypothesis is true. It is a pre chosen probability that cannot be exceeded while rejecting H₀ when it is true. P(rejecthing H₀|H₀)=alpha.