A Researcher Computes a One-Sample Z Test in Two Studies

Multiple Choice

A researcher computes a one-sample z test in two studies.Both studies used the same alpha level,placed the rejection region in both tails,and measured the same sample mean.The researcher selects a sample of 30 participants in Study 1 and decides to retain the null hypothesis.She selects a sample of 60 participants in Study 2 and decides to reject the null hypothesis.Which of the following is the best explanation for why the decision was different in Study 1 and Study 2?

A) The different decisions in Study 1 and Study 2 are not possible because all values were the same.
B) The different decisions in Study 1 and Study 2 are not possible because the researcher tested the same hypothesis.
C) The different decisions in Study 1 and Study 2 are due to an error the researcher made in the first hypothesis test.
D) The different decisions in Study 1 and Study 2 are possible because the second test was associated with greater power to detect an effect.