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.

Question

Quizplus · Accepted Answer

The different decisions in Study 1 and Study 2 are due to the fact that Study 2 had a larger sample size, which increased the power of the test to detect an effect. This resulted in the rejection of the null hypothesis in Study 2, whereas the null hypothesis was retained in Study 1.

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