Figure 6.

Calibration plots for validation of the model for grade ≥ 2 acute salivary dysfunction in the two independent external cohorts: (A) nasopharyngeal cancer (NPC) cohort and (B) head and neck cancer other than NPC cohort (HNC). Calibration plots present the rate of observed events in a group of patients (y-axis) vs. the mean predicted probability for the same group (x-axis). Groups of patients are ordered for increasing predicted probability. Error bars represent the confidence interval in observed frequencies calculated from proportions in the study population and based on a normal distribution of events. The dotted line is the identity line, identifying perfect calibration, the continuous black line is the calibration line. The calibration slope and calibration-in-the-large are also reported.