Table 1.
Power estimates based on the fixed effect, random effects, and withinsubject correlationa
| Fixed effect (β) | Random effects (G side) | Within-subject correlation (ρ) | Power |
|---|---|---|---|
| 0.982 | 0.1 | 0.6 | 74.0% |
| 1.022 | 0.5 | 0.6 | 76.3% |
| 1.138 | 1 | 0.6 | 83.5% |
| 1.514 | 2 | 0.6 | 96.7% |
| 1.989 | 3 | 0.6 | 99.9% |
| 1.138 | 1 | 0.3 | 94.9% |
| 1.138 | 1 | 0.4 | 91.4% |
| 1.138 | 1 | 0.5 | 87.6% |
| 1.138 | 1 | 0.7 | 83.5% |
| 1.138 | 1 | 0.8 | 79.5% |
| 1.138 | 1 | 0.9 | 72.0% |
a
Estimates are for a two-group longitudinal study with 100 subjects in the treatment group and 100 subjects in the control group and with 4 repeated measures for each subject. We assume CS within subject covariance structure and α = 0.05.