Table 5.
Reliability of the Dutch OKS-APQ
| Study sample | Pooled sample (n = 131) | Preoperative sample (n = 72) | Postoperative sample (n = 59) |
| Cronbach α | 0.95 | 0.81 | 0.95 |
| Test–retest sample | Preoperative sample (n = 12) | Postoperative sample (n = 38) | |
| OKS-APQ test median (25th–75th percentile) | 9.38 (0.00–29.69) | 67.19 (27.34–82.03) | |
| OKS-APQ retest median (25th–75th percentile) | 15.63 (0.78–28.13) | 62.50 (21.88–78.13) | |
| ICC (95% CI) | 0.63 (0.10–0.88) | 0.85 (0.72–0.92) | |
| Variance components | |||
| σ2p | 125.62 | 820.31 | |
| σ2o | 0.00 | 2.08 | |
| σ2residual | 72.02 | 147.49 | |
| SEM | 8.49 | 12.23 | |
| SDCind | 23.53 | 34.00 | |
| SDCgroup | 6.79 | 5.52 | |
σ2p: The variance of the patients (i.e. the systematic differences between the ‘true’ scores of the patients; σ2o: Variance due to systematic differences between observers/timepoints; σ2residual: Residual variance (i.e. random error variance)
ICC Intraclass correlation coefficient, SEM Standard error of measurement, SDCind Smallest detectable change in one individual, SDCgroup Smallest detectable change in a group