117 6 Appendix Appendix 1. Receiver operating characteristic (ROC) curve for mastication problems after treatment for head and neck cancer, using the linear mixed model The area under the curve (AUC) is 0.947. The AUC at the different assessment moments is 0.935 (T0), 0.951 (M3), 0.967 (M6), 0.948 (M12), and 0.953 (M24). The AUC can vary between 0 and 1, where a value of 0 indicated that the model has no diagnostic power, and a value of 1 indicates that the model has a perfect diagnostic accuracy