Table 1.

Single-stage (n*), minimax and optimal two-stage designs with λ₀ = 0.7 and a follow-up time of b = 1 year

			Minimax Design						Optimal Design
r	Δ	n*	n1(τ)	c1	n	c	EN	PET	n1(τ)	c1	n	c	EN	PET
	(α, 1 − β) = (.05, .9)
30	1.4	97	62(2.07)	0.215	98	−1.643	82.8	.41	57(1.90)	−0.130	107	−1.633	79.2	.55
	1.5	73	49(1.60)	0.520	74	−1.643	65.6	.30	45(1.47)	0.010	80	−1.631	61.7	.50
	1.6	59	46(1.53)	0.500	59	−1.643	54.9	.31	35(1.17)	0.130	64	−1.630	50.9	.45
	1.7	50	34(1.13)	0.490	51	−1.640	45.1	.31	31(1.00)	0.230	54	−1.630	43.7	.41
	(α, 1 − β) = (.1, .9)
	1.4	78	58(1.93)	0.610	78	−1.280	72.3	.27	49(1.60)	0.185	84	−1.265	68.4	.43
	1.5	59	45(1.47)	0.830	59	−1.280	55.7	.20	37(1.20)	0.350	63	−1.265	53.0	.36
	1.6	48	33(1.07)	0.705	48	−1.275	44.0	.24	31(1.00)	0.455	50	−1.265	43.4	.32
	1.7	40	31(1.03)	1.080	40	−1.280	38.5	.14	25(0.83)	0.560	42	−1.265	36.9	.29
	(α, 1 − β) = (.05, .85)
	1.4	85	54(1.80)	0.330	86	−1.643	73.9	.37	49(1.60)	−0.075	94	−1.628	69.5	.53
	1.5	65	43(1.43)	0.320	66	−1.640	56.9	.37	38(1.27)	−0.020	72	−1.624	54.3	.51
	1.6	53	34(1.13)	0.585	53	−1.641	47.3	.28	31(1.00)	0.105	58	−1.622	44.9	.46
	1.7	44	27(0.90)	0.555	45	−1.638	39.5	.29	27(0.87)	0.190	48	−1.622	38.5	.42
	(α, 1 − β) = (.05, .9)
60	1.4	113	78(1.30)	0.665	113	−1.643	103.7	.25	70(1.17)	0.105	122	−1.628	97.9	.46
	1.5	85	58(0.97)	0.670	86	−1.641	78.7	.25	53(0.87)	0.320	91	−1.630	76.2	.37
	1.6	69	49(0.82)	0.710	69	−1.640	64.2	.24	42(0.70)	0.420	73	−1.628	62.5	.34
	1.7	58	41(0.67)	1.090	58	−1.643	55.1	.14	37(0.60)	0.525	61	−1.630	53.2	.30
	(α, 1 − β) = (.1, .9)
	1.4	90	65(1.07)	0.900	91	−1.278	85.4	.18	57(0.95)	0.480	96	−1.265	83.2	.32
	1.5	68	45(0.73)	1.050	69	−1.277	64.8	.15	45(0.73)	0.695	71	−1.268	64.0	.24
	1.6	55	41(0.67)	1.085	55	−1.277	52.6	.14	35(0.58)	0.775	57	−1.266	51.9	.22
	1.7	46	29(0.48)	1.110	47	−1.274	43.8	.13	29(0.47)	0.920	48	−1.268	43.7	.18
	(α, 1 − β) = (.05, .85)
	1.4	99	83(1.37)	0.585	99	−1.643	93.9	.28	60(0.98)	0.130	108	−1.624	85.8	.45
	1.5	75	57(0.93)	0.725	75	−1.641	70.5	.23	46(0.75)	0.270	81	−1.622	66.8	.39
	1.6	61	46(0.75)	1.100	61	−1.643	58.1	.14	37(0.60)	0.370	66	−1.621	54.8	.36
	1.7	51	34(0.57)	0.870	51	−1.638	47.7	.19	29(0.48)	0.535	54	−1.624	46.5	.30