Table 2.
Comparison of a two-stage design with internal pilot and fixed sample size designs in a randomized study assuming a 20-percentage-point effect size and 80% power at 5% significance.
| Scenario | Properties | Fixed design (N=49) | Fixed design (N=70) | Internal pilot (n1=30) |
|---|---|---|---|---|
| Placebo: 10% Treatment: 30% |
Power | 80% | 91% | 84% |
| Ave Na IQRb |
49 (49–49) |
70 (70–70) |
54 (50–56) |
|
| Placebo: 25% Treatment: 45% |
Power | 64% | 80% | 80% |
| Ave Na IQRb |
49 (49–49) |
70 (70–70) |
70 (68–74) |
a
Per arm;
b
Interquartile range.