Baseline prevalence | 30% | 30% | 30% | 35% | 35% | 35% | |||
Improvement in control (A) | −3.0% | −3.0% | −3.0% | −3.5% | −3.5% | −3.5% | |||
Improvement in intervention (B) | −9.0% | −10.5% | −12.0% | −10.5% | −12.3% | −14% | |||
Intervention effect size (B – A): | -6% | −8% | −9% | −7% | −9% | −11% | |||
Power if sample size = 800 | 51% | 71% | 86% | 61% | 81% | 93% | |||
Power if sample size = 900 | 56% | 76% | 90% | 66% | 85% | 95% | |||
Power if sample size = 1000 | 60% | 80% | 92% | 71% | 88% | 97% | |||
Power if sample size = 1100 | 64% | 84% | 94% | 75% | 91% | 98% | |||
Power if sample size = 1200 | 68% | 87% | 96% | 78% | 93% | 99% | |||
Using type I error in the analysis: alpha= | 0.05 | 0.05 | 0.05 | 0.05 | 0.05 | 0.05 | |||
Expected baseline prevalence in both groups: A= | 30% | 30% | 30% | 35% | 35% | 35% | |||
Expected improvement in control group: B= | −3.0% | −3.0% | −3.0% | −3.5% | −3.5% | −3.5% | |||
Expected improvement in intervention group: C= | −9.0% | −10.5% | −12.0% | −10.5% | −12.3% | −14.0% | |||
Therefore the effect of Intervention is: C-B = | -6% | −8% | −9% | −7% | −9% | −11% | |||
Sample per group per period | 1000 | 1.2 | 833 | 53% | 72% | 87% | 63% | 82% | 94% |
Sample per group per period | 1100 | 1.2 | 917 | 57% | 76% | 90% | 67% | 86% | 96% |
Sample per group per period | 1200 | 1.2 | 1000 | 60% | 80% | 92% | 71% | 88% | 97% |
Sample per group per period | 1000 | 1.4 | 714 | 47% | 66% | 82% | 56% | 76% | 90% |
Sample per group per period | 1100 | 1.4 | 786 | 50% | 70% | 85% | 60% | 80% | 92% |
Sample per group per period | 1200 | 1.4 | 857 | 54% | 74% | 88% | 64% | 83% | 94% |
 | (A) | (B) | (C) |  |  |  |  |  |  |