The global relationship between actual errors and standard deviations is examined using Spearman's rank correlation coefficient, as illustrated in Figure uncertainties is analyzed through sparsification, as presented in Figure (c) and (f). Apart from GPR, the RMSE decreases as more data points with high uncertainty are removed, corroborating the models' effectiveness in uncertainty estimation. This trend reaffirms that GPR struggles to align actual errors with predicted uncertainties, highlighting a critical area for model refinement.