Fig. 4

Calibration curves of the prediction nomogram in the training cohort (A) and validation cohort (B). The x-axis represents the nomogram-predicted probability, and the y-axis represents the actual probability of PAL. The black pointed line represents the ideal curve, the red solid line represents the apparent curve (non-correction), and the blue solid line represents the bias-correction curve by bootstrapping (B = 1000 repetitions). PAL, prolonged air leak