Abstract

A MULTIPLE COMPARISON PROCEDURE FOR COMPARING SEVERAL TREATMENTS WITH A CONTROL CHARLES W. DUNNETT* American Cyanamid Company 1. INTRODUCTION COMMON problem in applied research is the comparison of treat­ ments with a control or standard. Such a situation may arise, for example, when an agronomist tests the effects on crop yield of the addi­ tion of chemicals to the soil, or when a pharmacologist assays drug samples to determine their potencies. In designing an experiment to measure the effects of such treatments, it is often desirable to include in the experiment a control in the form of either a dummy treatment, to measure the magnitude of the experimental response in the absence of the treatments under investigation, or some recognized standard treatment. Sometimes past experience with the control will suffice, but often this cannot be relied upon due to altered environmental con­ ditions. Thus the agronomist may leave a few of his experimental plots untreated for comparison with the treated plots, and the pharmacolo­ gist may measure the response to a standard drug preparation of known potency concomitantly with the test samples in order to esti­ mate the potencies of the latter. We will consider the case where the