Fig. 1: Modelling VOC profiles from skin swabs of Parkinson’s disease and control participants.

a Optimised sPLS-DA shows two clusters distinctly separating PD (pink) and controls (blue), validated by 3-fold cross validation with 100 repeats. b Example box plots for six of the 85 significant features, chosen to demonstrate changes in mean expression in PD and controls, selected using VIP scores (>1) and cross-validation feature stability scores (>0.8). For further details on the selection of these features, see supplementary information.