When the necessary conditions are met, a two-tail test is being conducted to test the difference between two population means, but your statistical software provides only a one-tail area of 0.156 as part of its output. The p-value for this test will be 0.078.

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Quizplus · Accepted Answer

If the software only provides a one-tail area, then it is likely that it is performing a one-tail test. Therefore, the reported p-value would correspond to the one-tail area and would need to be doubled to obtain the p-value for the two-tail test. In this case, 0.078 x 2 = 0.156, which is the reported one-tail area.

When the Necessary Conditions Are Met, a Two-Tail Test Is