Testing the hypothesis that treatments have negligible effects: Minimum-effect tests in the general linear model

Researchers are often interested in testing the hypothesis that the effects of treatments, interventions, and so on are negligibly small rather than testing the hypothesis that treatments have no effect whatsoever. A number of procedures for conducting such tests have been suggested but have yet to be widely adopted. In this article, simple methods of testing such minimum-effect hypotheses are illustrated in a variety of applications of the general linear model. Tables and computational routines that can be used in conjunction with the familiar F test to evaluate the hypothesis that the effects of treatments or interventions exceed some minimum level are also provided.