A researcher evaluates a treatment effect using a one-tailed hypothesis test with $\alpha$ = .05,and the decision is to reject the null hypothesis.If the researcher switched to a two-tailed test using the same sample,what decision would be made?
A)Definitely reject the null hypothesis with either $\alpha$ = .05 or with $\alpha$ = .01
B)Definitely reject the null hypothesis with $\alpha$ = .05 and maybe reject with $\alpha$= .01
C)Might reject the null hypothesis with $\alpha$ = .05 but might not
D)Definitely fail to reject the null hypothesis with either $\alpha$ = .05 or with $\alpha$ = .01

Question

Quizplus · Accepted Answer

Switching from a one-tailed test to a two-tailed test would require dividing the p-value by 2, which would make it harder to reject the null hypothesis. Therefore, it is possible that the null hypothesis might not be rejected with a two-tailed test, even though it was rejected with a one-tailed test. Thus, the best choice is C, as it suggests that there is a possibility that the null hypothesis might not be rejected with a two-tailed test.

A Researcher Evaluates a Treatment Effect Using a One-Tailed Hypothesis α\alphaα

A Researcher Evaluates a Treatment Effect Using a One-Tailed Hypothesis $\alpha$