Figure 2: (a) Proportion of variation explained by each principal component based on all 24 CATSYS measures, and adjusted for age. The first 3 principal components account for the majority total data variation (~60%). (b) The 24 individual variables of the CATSYS and their correlation to the first 3 principal components. The first PC (PC1) summarizes predominantly all sway tasks; the second PC (PC2) is primarily correlated with intention tremor (DotTrem) and writing tremor (WritTrem) in both hands; the third PC (PC3) captures association with postural tremor (TremInt) and reaction time in both hands. S1: SwayO60Mean, S2: SwayO60Area, S3: SwayO60Int, S4: SwayO30Mean, S5: SwayO30Area, S6: SwayO30Int, S7: SwayC30Mean, S8: SwayC30Area, S9: SwayC30Int, S10: SwayC10Mean, S11: SwayC10Area, S12: SwayC10Int, T1: TremIntDom, T2: TremIntNonDom, D1: DotTremIntDom, D2: DotTremIntNonDom, W1: WritTremIntDom, W2: WritTremIntNonDom, M1: MaxfreqDom, M2: MaxfreqNonDom, M3: MaxfreqTapDom, M4: MaxfreqTapNonDom, R1: ReactAvgDom, R2: ReactAvgNonDom.