Table 3.
Model diagnosticsa
| Measure | Apparent performance (95% CI)b | Test performance (95% CI)c | Average optimism (95% CI)d | Optimism corrected performance (95% CI)e | External validation (CPRD Aurum) (95% CI) |
|---|---|---|---|---|---|
| Overall calibration slope | 1.00 (0.75, 1.25) | 0.72 (0.50–0.94) | 0.28 | 0.72 (0.47–0.97) | 0.91 (0.74–1.07) |
| Royston D statistic | 1.06 (0.77, 1.35) | 0.90 (0.63–1.17) | 0.33 | 0.73 (0.44–1.02) | 0.97 (0.89–1.05) |
| R 2 | 0.21 (0.12, 0.30) | 0.16 (0.08–0.24) | 0.10 | 0.11 (0.02–0.20) | 0.18 (0.16–0.21) |
a
Results from a single imputed dataset but similar across the other imputations (data not shown).
b
Refers to performance (95% CI) estimated directly from the data that was used to develop the model.
c
Determined by executing the full model in each bootstrap sample (500 samples with replacement), calculating bootstrap performance and applying same model in the original sample.
d
Average difference between model performance in bootstrap data and test performance in the original dataset.
e
Subtracting average optimism from apparent performance.