Nomogram to predict the risk of endoscopic removal failure with forceps/baskets for treating submandibular stones

Figure 4 Receiver operating characteristic curve analysis. A: To determine the optimal cutoff points for the location, transverse diameter (TD) and longitudinal diameter (LD) of the stones; B: To compare the predictive performance of the univariate and multivariate combined models. In B, the univariate model of TD, LD and location correspond to models 1, 2 and 3, respectively. Model 2 and model 3 are so close that it is difficult to distinguish them graphically. The multivariate combined model corresponds to model 4.