Table 3 Approximate maximum intra-class correlation (ICC) for various cluster sizes and number of intervention hospitals to answer primary hypothesis
Number of intervention (and control) hospitals | Average size of cluster | Maximum ICC to have 80% power to detect 5% difference |
|---|---|---|
8 | 400 | 0.01 |
15 | 400 | 0.02 |
21 | 400 | 0.03 |
9 | 300 | 0.01 |
15 | 300 | 0.02 |
22 | 300 | 0.03 |
10 | 200 | 0.01 |
16 | 200 | 0.02 |
23 | 200 | 0.03 |