Skip to main content

Table 1 Required sample size per arm as a function of the coefficient of variation and the number of clinical centers

From: Accounting for treatment by center interaction in sample size determinations and the use of surrogate outcomes in the pessary for the prevention of preterm birth trial: a simulation study

Coefficient of variation Probability that π Si >0.225 Number of clinical centers
20 40 60 80 100
0 1 610 580 560 540 520
0.1 0.99 660 600 580 560 530
0.2 0.90 880 700 650 600 560
0.3 0.79 1840 1000 800 700 640
0.4 0.71 50,000 1700 1200 900 800