Table 6.

Joint probabilities of final decisions for TTB and PFS for Scenarios 0, 6, 17, and 18 using three interim analyses. Operating characteristics for conventional bivariate sequential design using O’Brien Fleming monitoring boundaries are provided in parentheses, ().

Scenario 0: Identical mean TTB and PFS hazard (global null)
			TTB Decision
		PBT Better	Indeterminate	IMRT Better
	PBT Better	0.00 (0.00)	0.02 (0.02)	0.00 (0.00)
PFS Decision	Indeterminate	0.01 (0.01)	0.93 (0.93)	0.01 (0.01)
	IMRT Better	0.00 (0.00)	0.02 (0.02)	0.00 (0.00)
Early Stopping Probability = 0.04 (0.01);		Mean Sample Size = 178 (180)
Scenario 6: 50% reduction in mean TTB for PBT and PFS HR= 1 (null case)
			TTB Decision
		PBT Better	Indeterminate	IMRT Better
	PBT Better	0.01 (0.005)	0.01 (0.01)	0.00 (0.00)
PFS Decision	Indeterminate	0.88 (0.66)	0.07 (0.31)	0.00 (0.00)
	IMRT Better	0.01 (0.005)	0.02 (0.01)	0.00 (0.00)
Early Stopping Probability = 0.68 (0.30);		Mean Sample Size = 144 (167)
Scenario 17: 50% reduction in mean TTB for PBT and PFS HR= 2 (in favor of PBT)
			TTB Decision
		PBT Better	Indeterminate	IMRT Better
	PBT Better	0.20 (0.16)	0.42 (0.65)	0.00 (0.00)
PFS Decision	Indeterminate	0.37 (0.15)	0.01 (0.04)	0.00 (0.00)
	IMRT Better	0.00 (0.00)	0.00 (0.00)	0.00 (0.00)
Early Stopping Probability = 0.89 (0.65);		Mean Sample Size = 125 (152)
Scenario 18: 50% reduction in mean TTB for PBT and PFS HR= 0.5 (in favor of IMRT)
			TTB Decision
		PBT Better	Indeterminate	IMRT Better
	PBT Better	0.00 (0.00)	0.00 (0.00)	0.00 (0.00)
PFS Decision	Indeterminate	0.33 (0.35)	0.01 (0.02)	0.00 (0.00)
	IMRT Better	0.21 (0.29)	0.45 (0.34)	0.00 (0.00)
Early Stopping Probability = 0.88 (0.73);		Mean Sample Size = 126 (147)