alpha spending functions;
group sequential design;
optimal design;
D O I:
10.1002/bimj.200510205
中图分类号:
Q [生物科学];
学科分类号:
07 ;
0710 ;
09 ;
摘要:
We present optimized group sequential designs where testing of a single parameter 0 is of interest. We require specification of a loss function and of a prior distribution for theta. For the examples presented, we pre-specify Type I and II error rates and minimize the expected sample size over the prior distribution for theta. Minimizing the square of sample size rather than the sample size is found to produce designs with slightly less aggressive interim stopping rules and smaller maximum sample sizes with essentially identical expected sample size. We compare optimal designs using Hwang-Shih-DeCani and Kim-De-Mets spending functions to fully optimized designs not restricted by a spending function family. In the examples selected, we also examine when there might be substantial benefit gained by adding an interim analysis. Finally, we provide specific optimal asymmetric spending function designs that should be generally useful and simply applied when a design with minimal expected sample size is desired.
机构:
Amer Coll Radiol, Philadelphia, PA 19103 USA
Univ Penn, Dept Biostat & Epidemiol, Philadelphia, PA 19104 USAAmer Coll Radiol, Philadelphia, PA 19103 USA