A researcher obtains z = -6.45.What is the decision for a one-tailed test,upper-tail critical,at a .05 level of significance?
A) to reject the null hypothesis
B) to retain the null hypothesis
C) it depends on the sample size
D) there is not enough information to make a decision

Question

Quizplus · Accepted Answer

In a one-tailed test, specifically an upper-tail test, a negative z-score (like -6.45) indicates that the sample mean is significantly lower than the population mean hypothesized under the null hypothesis. However, since we're looking at the upper tail, we're interested in whether the sample mean is significantly higher, not lower. Therefore, a negative z-score does not lead to rejecting the null hypothesis at the .05 level of significance in an upper-tail test. We retain the null hypothesis because the evidence does not support a significantly higher mean than hypothesized.

A Researcher Obtains Z = -6