ABSTRACT
This chapter focuses on the general concepts behind multiplicity in the context of confirmatory trials that compare several doses with a control. Multiple test procedures can generally be divided into two categories: single-step tests and stepwise test procedures. Single-step procedures are characterized by the fact that the rejection or non-rejection of a null hypothesis does not take the decisions for any other hypothesis into account. In contrast, for stepwise procedures, the rejection or non-rejection of a null hypothesis may depend on the decision of other hypotheses. The simplest method for controlling family-wise error rate (FWER) is the Bonferroni test, which divides the significance level equally among all of the hypothesis tests. The fixed-sequence approach has advantage of being simple, and it controls FWER in the strong sense. The closed test procedure is a key principle for constructing multiple test procedures. The chapter describes an extension of the MCP-Mod approach using the closed test procedure, which does allow such individual statements.
