The SEQDESIGN Procedure

Output from the SEQDESIGN Procedure

In addition to computing the boundary values for a group sequential design, the SEQDESIGN procedure computes the following quantities:

  • maximum sample size (as a percentage of the corresponding fixed-sample size) if the trial does not stop at an interim stage

  • average sample numbers (as percentages of the corresponding fixed-sample sizes for nonsurvival data or fixed-sample numbers of events for survival data) under various hypothetical references, including the null and alternative references

  • stopping probabilities at each stage under various hypothetical references to indicate how likely it is that the trial will stop at that stage

  • sample sizes required at each stage for the specified hypothesis test

  • numbers of events required at each stage for the specified hypothesis test with survival data

You can create more than one design with multiple DESIGN statements in the SEQDESIGN procedure and then choose the design with the most desirable features. The next two subsections introduce some basic aspects of group sequential designs that are useful for getting started with the SEQDESIGN procedure.