To do a one-tail t test, as opposed to a two-tail,
A) the direction of the difference must always be specified beforehand
B) the direction of the difference need only be specified after null has been rejected
C) the direction of the difference must only be specified when null is accepted
D) the direction of the difference becomes irrelevant

Question

Quizplus · Accepted Answer

In a one-tail t test, the direction of the difference must always be specified beforehand, as the null hypothesis is only being tested in that specific direction. If the alternative hypothesis is formulated as a one-tail test but the direction is not specified beforehand, the hypothesis can be ambiguous and data can be interpreted to support the hypothesis in either direction.

To Do a One-Tail T Test, as Opposed to a Two-Tail