Some new multiple-test procedures for dose finding

In Tamhane, Hochberg, and Dunnett (1) we focused primarily on step-down test procedures based on contrasts among the sample means to find the minimum effective dose in a dose-response study. In the present article we use the global tests of Bartholomew (2,3) and Hayter (4) in these step-down procedures. We also propose a new step-down procedure that permits tests based on a class of contrasts [step and basin contrasts of Ruberg (5) are examples of such contrasts] that could not be used with the step-down procedures studied in our previous paper because of lack of control of the familywise error rate. A simulation study to compare the four procedures proposed in the present paper with the top four procedures from the previous article is carried out. It is found that the step-down procedure based on Bartholomew's test and the new step-down procedure based on step and modified basin contrasts generally perform better than the other procedures for a wide range of dose-response profiles.