When testing a directional hypothesis, we always must use a one-tailed test of significance; there are no exceptions to this rule.

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Quizplus · Accepted Answer

This statement is false. While a directional hypothesis may lend itself to a one-tailed test, it is not always necessary or appropriate. In some cases, a two-tailed test may be more appropriate, depending on the research question and the data being analyzed.

When Testing a Directional Hypothesis, We Always Must Use a One-Tailed