Table 1.

Sample sizes of SMARTer to achieve the same efficiency as SMART with 100 subjects for comparing two DTRs with different first stage treatments

α	0		0.2		0.4		0.5		0.6		0.8
SMARTera			β = 0.5
	n	m	n	m	n	m	n	m	n	m	n	m
γ = 0.5	100	50	92	46	91	46	92	46	93	46	96	48
γ = 1	125	62	109	54	102	51	100	50	99	50	99	49
γ = 2	150	75	125	62	112	56	108	54	105	53	102	51
			β = 1
γ = 0.5	67	67	73	73	80	80	83	83	87	87	93	93
γ = 1	75	75	80	80	85	85	88	88	90	90	95	95
γ = 2	83	83	87	87	90	90	92	92	93	93	97	97
			β = 2
γ = 0.5	50	100	61	122	72	143	77	153	82	163	91	182
γ = 1	50	100	62	124	73	145	78	155	82	165	91	183
γ = 2	50	100	62	125	73	147	78	157	83	166	92	184
SMART-misb	NA		500		250		200		167		125

^aSample sizes for SMARTer are to achieve same efficiency as a SMART trial with 100 patients and in an ideal case of no dropout. n is the sample size for the SMART group, m is the sample size for the enrichment group; β = m/n is the ratio of sample size between enrichment and SMART group; α is the completion rate; γ is ratio of within- and between-stratum variance.

^bSMART-mis is the sample size for a SMART accounting for the dropout rate of 1 − α in the second stage in the design, that is, 100/α.