Notes on power comparison between the sequential parallel comparison and other commonly-used designs

Abstract

Because one excludes in the sequential parallel comparison design (SPCD) both placebo responders and patients assigned to the experimental treatment in period 1 from comparison in period 2, test procedures for the SPCD may lose efficiency.? We evaluate the loss of efficiency by comparing power of the SPCD with those for the parallel groups design with repeated measurements (PGDRM), the simple crossover design (SCD), and the parallel group design (PGD). Using Monte Carlo simulations, we demonstrate that one can increase the efficiency of the SPCD by use of the PGDRM and SCD. However, the SPCD may be of use if we wish to assess the treatment effect under the simple carry-over model.