Table 4.

Properties of estimates based on 1000 simulations. Estimates are mean values over simulations. The sample size ratio is the size of the new trial divided by the average size of the previous trials. The 95% prediction was computed at the median value of the effect of treatment on the surrogate endpoint among the previous trials.

Sample size ratio	Number of trials	Between-trial standard error =σ			Slope = β			Coverage of the 95% prediction interval
		True	Approximate MLE	MLE	True	Approximate MLE	MLE
1.0	10	5	4.37	4.37	2	2.00	2.01	0.93
		2	1.41	1.41	2	2.00	2.00	0.99
	30	5	4.80	4.80	2	2.00	2.00	0.96
		2	1.67	1.67	2	2.00	2.01	1.00
0.2	10	5	4.37	4.37	2	2.00	2.00	1.00
		2	1.41	1.41	2	2.00	2.00	1.00
	30	5	4.80	4.80	2	2.00	2.00	1.00
		2	1.67	1.67	2	2.00	2.00	1.00