Directional Hypothesis

In statistics and science, a directional hypothesis predicts that a specific relationship between numbers or objects will exist, and furthermore, the direction in which that relationship is heading.

In math, this relates to the concept of the null hypothesis where a two-tailed solution might exist, but that only one of those solutions is valid. In a non-directional hypothesis the arousal and the test performance are closely related to each other and predicts that the independent variable will have an effect on the dependent variable, e.g. the flow rate of molasses is directly related to the ambient temperature of the room.