Figure 3.
The correlation matrix (upper triangular matrix, r-value ranging from −1 to 1) of all noise regressors for noise sources 1) −4) is displayed, showing the collinearity between regressors. In the lower triangular matrix a contour plot highlighting regressors with significant collinearity (p < 0.05) is shown. At this statistical threshold (but not for p < 0.001) some regressors for different noise sources are collinear (see for example low frequency drifts and RVT regressors, or RVT regressors with cardiac-rate regressors).