Table 4.

Average sample size and empirical probability of rejecting the null hypothesis, design with interim futility monitoring: Equal subgroup accrual rates (10,000 replications)

Design		True response rate in each subgroup
Case 1		.1	.1	.1	.1	.1
Subgroup-specific analyses	Average sample size	19.4	19.5	19.5	19.5	19.5
	Rejection probability	.093	.096	.094	.098	.098
HB* Model 1 Moderate borrowing	Average sample size	19.6	19.6	19.6	19.6	19.4
	Rejection probability	.091	.094	.094	.097	.097
Simple borrowing (LeBlanc et al)	Average sample size	16.2	16.3	16.3	16.3	16.3
	Rejection probability	.064	.067	.069	.068	.071
Case 2		.1	.1	.1	.1	.3
Subgroup-specific analyses	Average sample size	19.5	19.5	19.5	19.5	24.6
	Rejection probability	.092	.089	.096	.087	.900
HB Model 1 Moderate borrowing	Average sample size	20.0	20.0	20.0	19.9	24.4
	Rejection probability	.092	.090	.097	.088	.892
Simple borrowing (LeBlanc et al)	Average sample size	18.6	18.6	18.7	18.7	22.8
	Rejection probability	.086	.084	.091	.084	.776
Case 3		.1	.1	.1	.3	.3
Subgroup-specific analyses	Average sample size	19.4	19.4	19.4	24.6	24.6
	Rejection probability	.093	.092	.089	.897	.900
HB Model 1 Moderate borrowing	Average sample size	20.4	20.4	20.4	24.5	24.6
	Rejection probability	.094	.093	.090	.895	.894
Simple borrowing (LeBlanc et al)	Average sample size	19.3	19.2	19.3	24.0	24.1
	Rejection probability	.092	.091	.089	.875	.874
Case 4		.1	.1	.3	.3	.3
Subgroup-specific analyses	Average sample size	19.5	19.5	24.6	24.7	24.6
	Rejection probability	.097	.095	.900	.901	.892
HB Model 1 Moderate borrowing	Average sample size	21.0	21.0	24.6	24.6	24.6
	Rejection probability	.100	.098	.901	.902	.891
Simple borrowing (LeBlanc et al)	Average sample size	19.5	19.4	24.5	24.6	24.6
	Rejection probability	.097	.095	.898	.899	.889

^*HB = hierarchical Bayesian