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 t esting the hypothesis that treatments have no effect whatsoever. A number o f 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 gener al linear model. Tables and computational routines that can be used in conj unction with the familiar F test to evaluate the hypothesis that the effect s of treatments or interventions exceed some minimum level are also provide d.