Fig. 4

Correlation structure of the UHPC dataset batches). Left: heatmap of pairwise Pearson correlation coefficients (\(\rho\)); right: bar plot of the row-wise sum of absolute correlations (\(|\!\sum \rho |\)), a scalar summary of how strongly each variable co-varies with the remaining feature space. Lower \(|\!\sum \rho |\) indicates lower collinearity and greater uniqueness; features with the lowest values—CT28, CC28, IM, GRP—retain comparatively unique information for subsequent modeling. Abbreviations for variables are defined in Table 1.