Table 1 Required samples sizes for three different scenarios of increases in risk-appropriate screening in the intervention arm compared to the control arm, assuming rate of risk-appropriate screening of 1% and 25% at baseline and level of significance = 0.05
Scenario (intervention vs control) | Absolute difference in appropriate screening | Power | Sample size per arm | Sample size per arm allowing for 10% attrition |
|---|---|---|---|---|
10% improvement vs 0% | 11% vs 1% | 90% | 117 | 130 |
10% improvement vs 2.5% | 11% vs 3.5% | 90% | 250 | 278 |
10% improvement vs 5% | 11% vs 6% | 90% | 652 | 725 |
10% improvement vs 0% | 35% vs 25% | 80% | 329 | 366 |