A hypothesis test for the difference between two means is considered a two-tailed test when:
A) the population variances are equal.
B) the null hypothesis states that the population means are equal.
C) the alpha level is 0.10 or higher.
D) the standard deviations are unknown.

Question

Quizplus · Accepted Answer

A two-tailed test is used when the alternative hypothesis specifies that the parameter of interest (in this case, the difference between two means) is not equal to the null hypothesis value. This implies that the research is interested in deviations in both directions from the null hypothesis value, not just one.

A Hypothesis Test for the Difference Between Two Means Is