Table 1 Sample size and power under different scenarios
Raw difference on the ADOS scale (SD = 5) | Standardised effect size (Cohen's d) | Power at first interim look1 | Test power over all 4 interim looks2 |
|---|---|---|---|
2.5 | 0.5 (medium effect) | 93% | 100% |
2 | 0.4 | 76% | 100% |
1.5 | 0.3 | 47% | 99% |
1 | 0.2 (small effect) | 20% | 80% |