Figure 3

(a) Results of the Principal Component Analysis with the dispersion of the first three PCs values with the relative 95% confidence interval ellipses for the three experimental groups and (b) linear discriminant analysis (LDA) representing the spatial distribution of the two CVs extracted with the group means. c) Statistical analysis of the CVs extracted from CTRL (n = 33), COV+  (n = 30) and COV− (n = 38). *** p-value < 0.001, One-way ANOVA test. (d) Graphical representation of the PCs loadings respect to one of the CTRL spectrum and (e) receiver operator characteristic (ROC) curve with the relative 95% confidence interval of the classification model CTRL vs COV+  vs COV−. Area under the curve = 0.9; Standard error = 0.008; Significant level p < 0.001 for area = 0.5 calculated following Delong et al. ⁴¹.