Designs for clinical trials with time-to-event outcomes based on stopping guidelines for lack of benefit

Table 1 Suggested significance level and power at each stage of a TAMS design with four stages and an allocation ratio of either 1 or 0.5.

Allocation Ratio	Stage	Significance level (1-sided)	Power	Number of events		Time
				Control arm	Total
A	i	α _i	ω _i	e _i		t _i
1	1	0.5	0.95	73	133	1.7
	2	0.25	0.95	139	256	2.6
	3	0.125	0.95	198	369	3.3
	4	0.025	0.9	264	486	5.0
0.5	1	0.5	0.95	113	160	1.9
	2	0.25	0.95	211	301	2.8
	3	0.125	0.95	301	432	3.6
	4	0.025	0.9	399	568	5.4

The number of events in the control arm and overall at each stage are shown, together with the time at which each stage ends. The assumptions underlying the calculations are described in the text.

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