SELECTING THE LARGEST INTERACTION IN A TWO-FACTOR EXPERIMENT

Publisher Summary The research described in this chapter involved the study of the effect of several different methods of treatment on a physiological response of male and female subjects—otherwise matched with respect to other factors that might affect the response—as required by a medical research worker. The study was undertaken with the consideration that the effect of the treatment on the mean response is different for men than for women and also that it varies from treatment to treatment. A large interaction between the sex and the method of treatment was suspected to identify the sex treatment combination for which this interaction is largest, in turn, deciphering the mechanism underlying the effectiveness of the methods of treatment. The statistical problem is to design the experiment on such a scale that this largest interaction can, if it is sufficiently large to be of practical importance to the experimenter, be detected with preassigned probability.