Table 1.

Fixed and constant parameter values for the interim analysis simulations

Description	Constant factors	Factors varied
Interim sample size	n = 50
Minimum required sample size	n = 600
Number of simulations	1000
Between-person SD	σb = 10 mmHg
Within person SD		σe = 9, 10 mmHg
Overall mean SBP (mmHg)	μ = 140 mmHg
Single treatment-by-ethnic interaction (mmHg)		δ = 3, 4 mmHg
Period effect (mmHg)	πj = 0 mmHg, ∀j
Power to detect a single ethnic by treatment interaction at 5% significance level (%)		1 − β = 0.1,0.2