A class of treatment assignment rules for sequential experiments

In an experiment to compare K(<2) treatments, suppose that eligible subjects arrive at an experimental site sequentially and must be treated immediately. In this paper, we assume that the size of the experiment cannot be predetermined and propose and analyze a class of treatment assignment rules which offer compromises between the complete randomization and the perfect balance schemes, A special case of these assignment rules is thoroughly investigated and is featured in the numerical compu-tations. For practical use, a method of implementation of this special rule is provided.