Table 1

Estimated statistical powers required for parallel group trials using different sample sizes and durations of follow up for different treatment effects using the number of new enhancing lesions (A.III) and the number of active scans (A.II) as the end point measure

Sample size		Effect (%)		Response variable		Duration of follow up (months)
Sample size		Effect (%)		Response variable		2	3	6	9
2×20	50	A.II	13	13	14	15
		A.III	14	17	19	21
	60	A.II	20	21	24	25
		A.III	28	35	37	37
	70	A.II	31	35	40	43
		A.III	37	54	57	57
2×30	50	A.II	16	18	21	22
		A.III	22	27	30	31
	60	A.II	27	31	36	39
		A.III	43	48	50	54
	70	A.II	45	51	58	60
		A.III	55	71	74	75
2×40	50	A.II	21	23	27	29
		A.III	26	33	38	40
	60	A.II	36	39	46	48
		A.III	54	62	62	67
	70	A.II	57	64	71	72
		A.III	69	83	85	87
2×50	50	A.II	24	27	32	34
		A.III	31	41	46	46
	60	A.II	43	48	55	58
		A.III	63	67	74	74
	70	A.II	69	73	80	81
		A.III	76	90	92	92