Results of the toy model fitting to test accuracy of the hierarchical fitting as well as origin of the C_⋆ − C_mol covariance. Each panel shows the posterior distribution obtained for a simulated data set. The black diamond and its error bar marks the median and 1-sigma of the posterior distribution. The blue square marks the real pair of C_⋆ − C_mol used to generate each simulated data set. The color code scales with the posterior value of C_norm.