Fig. 6

a, b Calibration curves of the prediction nomogram in training (a) and validation (b) sets. Calibration curves depict the calibration of the nomogram in terms of the agreement between the probability of the malignant potential of GISTs (Grade) and actual observation. The Y-axis represents the actual observed rates of high-malignant potential GIST whereas the X-axis represents the predicted malignancy probability estimated by the nomogram. The solid line represents the ideal reference line that predicted GIST malignant corresponds to the actual outcome, the short-dashed line represents the apparent prediction of nomogram, and the long-dashed line represents the ideal estimation. The actual GIST malignancy probability corresponded closely to the prediction of the nomogram