Table 3.

Comparison sample sizes calculated the exponential cure model using Wang’s formula and the new formula (6) with a nominal type I error of 0.05 and power of 90%: (two-sided test, uniform accrual and equal allocation).

		Wang		Formula (6)				Wang		Formula (6)
Design	δ−1/γ	nW	EPW	nX	EPX	Design	δ−1/γ	nW	EPW	nX	EPX
Scenario 1: η ≠ 0 γ ≠ 0
π0 = 0.4	1.2/0.4	927	0.887	972	0.903	π0 = 0.1	1.2/0.4	1377	0.893	1385	0.906
λ0 = 0.1	1.3/0.5	527	0.881	570	0.906	λ0 = 0.1	1.3/0.5	714	0.894	734	0.899
ta = 1	1.4/0.6	345	0.875	383	0.903	ta = 1	1.4/0.6	448	0.884	469	0.899
tf = 10	1.5/0.7	246	0.857	284	0.903	tf = 10	1.5/0.7	313	0.878	333	0.904
	1.6/0.8	186	0.853	221	0.904		1.6/0.8	234	0.886	253	0.903
	1.7/0.9	147	0.849	180	0.908		1.7/0.9	184	0.877	202	0.900
	1.8/1.0	119	0.834	152	0.912		1.8/1.0	150	0.870	166	0.902
Scenario 2: η ≠ 0 γ = 0
π0 = 0.4	1.4/0.0	1657	0.895	1668	0.902	π0 = 0.1	1.4/0.0	745	0.885	801	0.904
λ0 = 0.1	1.5/0.0	1141	0.903	1156	0.904	λ0 = 0.1	1.5/0.0	513	0.875	562	0.900
ta = 1	1.6/0.0	850	0.892	867	0.904	ta = 1	1.6/0.0	382	0.871	425	0.903
tf = 10	1.7/0.0	667	0.894	686	0.904	tf = 10	1.7/0.0	300	0.869	340	0.904
	1.8/0.0	543	0.888	565	0.906		1.8/0.0	245	0.853	282	0.901
	1.9/0.0	456	0.890	478	0.909		1.9/0.0	205	0.854	240	0.900
	2.0/0.0	391	0.889	414	0.910		2.0/0.0	176	0.855	209	0.907
Scenario 3: η = 0 γ ≠ 0
π0 = 0.4	1.0/1.0	420	0.941	360	0.906	π0 = 0.3	1.0/1.0	255	0.952	209	0.904
λ0 = 0.1	1.0/1.1	347	0.943	297	0.902	λ0 = 0.3	1.0/1.1	211	0.953	171	0.904
ta = 1	1.0/1.2	292	0.942	250	0.905	ta = 1	1.0/1.2	177	0.948	143	0.905
tf = 10	1.0/1.3	249	0.942	214	0.910	tf = 10	1.0/1.3	151	0.959	121	0.908
	1.0/1.4	214	0.944	186	0.910		1.0/1.4	130	0.956	105	0.910
	1.0/1.5	187	0.945	164	0.912		1.0/1.5	114	0.956	91	0.910
	1.0/1.6	164	0.940	146	0.912		1.0/1.6	100	0.954	81	0.908

abbreviation n_W and EP_W : sample size and empirical power calculated by formula derived by Wang at al.; abbreviation n_X and EP_X: sample size and empirical power calculated by formula (6).