Feature selection
PD
Several feature selection methods were tried in the training data, and the feature combinations were organized into 3 groups based on the feature selection method results.Method 1: Sixty-six out of 214 features were significantly different between early PD and ET (Table Method 2: 34 out of 66 features were kept (eTable 1 in the Online Resource); thus, FG II contained 34 features. In addition, 29, 3, 1, and 1 were obtained from the straight walk, turning, sitting, and standing components, respectively.Method 3: Out of the 66 significant features, 33 individual features were most discriminative in differentiating early PD from ET, with a fivefold cross-validation ROC AUC ≥ 0.6 (Table 