1. Statistics Department , Univeisity of Florida , Gainesville, FL, 32611;2. Irring Consultive Group , PO Box 238, NJ, 07078 0258;3. Biostatistics and Research Data Systems , Merk Research Laboratories , Rahway, NJ, 07065
Abstract:
We propose flexible group sequential designs using type I and type II error probability spending functions. The proposed designs preserve the overall significance level and power and allow the repeated testing to be perloimed at a flexible schedule. Computational methods are described. An example on a mega clinical trial is provided.