Appendix E: Weighted average ensemble classification model construction
PD, confusion
REGRESSION, DISEASE
This ensemble classification model construction included 18 steps:The entire TUG test was separated into four components: straight walk, turning, standing, and sitting.The response variable of each of the four component models was the diagnosis result – whether the subject was PD or ET (we defined PD as 1, ET as 0). Predictors were considered among the three-feature selection method results FG I, FG II, and FG III.Four components, namely, straight walk, turning, standing, and sitting, were trained separately using the training data with features from the corresponding components through LOOCV. Two types of basic models were tried here: support vector machine (SVM) and random forest (RF) models. For example, for the straight walk component, we only extracted the features related to straight walk from FG I and then utilized these features as input features to train the basic SVM and RF models ordinally through LOOCV to fine-tune the model parameters to obtain the best SVM model and best RF model for the straight walk component. Turning, sitting, and standing components followed the same process as the Straight Walk component. Therefore, there were 6 model and feature group combinations in total: FG I + basic model SVM, FG I + basic model RF, FG II + basic model SVM, FG II + basic model RF, FG III + basic model SVM, and FG III + basic model RF.For each of the feature groups and basic model combinations mentioned in Step 3, we repeated Step 5 to Step 13.The predicted probabilities of the disease being PD for each subject in the training data group obtained from each of the four component models were calculated and saved. In this case, each subject in the training data group should have four probabilities of being a PD, which were called predicted scores, corresponding to the four different components. The 4 predicted scores were noted as We combined the original response variable (diagnosis result) in the training data and 4 columns of the predicted probabilities above as a new dataset. The original response variable was also the response variable in the new dataset, and the other 4 columns of the predicted probabilities were used as the predictors.Logistic regression was run on this new dataset with a fivefold cross-validation method to fine-tune the model parameters to obtain the best logistic regression model.The captured 4 coefficients (ignoring the intercept) derived from the above logistic regression analysis corresponded to the four different components. These 4 coefficients were annotated as Four linear weights were calculated based on the coefficients obtained in Step 8:The calculated ensemble learning prediction probability score of each subject in the training data, If the The confusion matrix was constructed using the predicted label obtained from Step 11 and the true label (true diagnosis result) from the subjects in the training data.The cross-validation performance (accuracy, kappa, sensitivity, and specificity) of this weighted average ensemble classification model was calculated based on the confusion matrix constructed in Step 12, and the cross-validation performance (AUC) was calculated using the predicted value, The weighted average ensemble classification model, which had the best validation performance among the models, was selected as our final model.Predicted on test data using four trained models (straight walk, turning, standing, and sitting) from the best weighted average ensemble classification model separately and obtain the corresponding predicted probabilities of being a PD corresponding to the four different components for each subject in the test data. The 4 predicted probabilities were noted as The calculated ensemble learning prediction probability score of each subject in the test data group If The test data performance (AUC) was calculated using the predicted value, 