Table 5.

Optimal two-stage parameters for designs that minimize either the ETSL (top line) or the EDA (bottom line) for testing H₀: S(1) ≤ .35. Power is specified for S(1) = .5.^#

α	1 - β	DA/x*	t1	C1	C2	I1/Imax	EDA	MDA	ETSL	MTSL
.1	.9	1.50	1.01	.488	1.154	.49	1.05	1.15	.76	1.09
			.81	-.489	1.257	.32	.96	1.03	.85	1.02
		1.75	.93	.457	1.159	.48	1.00	1.15	.76	1.10
			.76	-.291	1.245	.34	.94	1.05	.82	1.03
		2	.87	.434	1.163	.47	.96	1.15	.75	1.10
			.72	-.179	1.237	.36	.92	1.06	.80	1.04
		3	.74	.375	1.172	.46	.88	1.15	.75	1.11
			.63	.004	1.220	.38	.86	1.09	.77	1.07
		4	.67	.346	1.176	.45	.84	1.15	.75	1.12
			.59	.073	1.212	.39	.83	1.10	.76	1.08
.05	.95	1.50	.99	.680	1.536	.46	1.03	1.17	.72	1.10
			.81	-.274	1.622	.32	.95	1.04	.81	1.02
		1.75	.91	.648	1.541	.46	.98	1.16	.72	1.10
			.75	-.084	1.612	.34	.92	1.06	.78	1.04
		2	.85	.624	1.545	.45	.94	1.16	.71	1.11
			.72	.024	1.605	.35	.89	1.07	.76	1.05
		3	.72	.563	1.553	.44	.85	1.16	.71	1.12
			.63	.202	1.591	.38	.83	1.10	.72	1.08
		4	.66	.531	1.557	.44	.80	1.15	.70	1.12
			.59	.266	1.586	.39	.79	1.11	.71	1.09

^# DA is the fixed sample duration of accrual; x* is the survival time of interest; t₁ is the time of the first interim review; C₁ and C₂ are the cutpoints for acceptance at the first stage and rejection at the second stage; I₁ and Imax are the information available at the interim and final reviews; EDA and MDA are the expected and maximum duration of accrual relative to the single stage values; and ETSL and MTSL are the expected and maximum total study length relative to the single stage values. Expected values are calculated under the null hypothesis.