Figure 3

Calibration results for both external validation stages. (a) Calibration curve for all models assessed on the first external validation dataset. (b) Calibration curve for the second external validation dataset. The blue dotted line (45°) represents perfect calibration (complete agreement between predicted and observed probabilities). When the colour line is above the reference, the model underestimates the true probability, whilst the model overestimates probabilities when the line is below the reference line.