Table III.
Longitudinal Parameter Estimates for the Unidimensional Item Response Theory (IRT) Model
| Parameter | Longitudinal unidimensional integrated IRT model | |
|---|---|---|
| Value | Relative standard error | |
| Baseline | − 0.0993 | 57.1 |
| Pmax (maximal placebo response) | − 1.22 | 9.2 |
| Tprog (placebo half-life) | 16.2 | 17.5 |
| Drug effect | − 0.565 | 19.3 |
| Covariates | ||
| Post-void residual volume on baseline | 0.00327 | 24.9 |
| Interindividual variability (IIV) | ||
| IIV Baseline | 104.4% | 5.5 |
| IIV Pmax | 134.9% | 13.9 |
| IIV Drift | 0.9% | 9 |
| IIV Tprog | 51.7% | 12.6 |
| IIV Baseline-Pmax correlation | 15.5% | 46.3 |
| IIV Pmax-Drift correlation | 45.4% | 36.5 |