Hexbin plots showing the ground truth from the PROSPECTOR-α stellar population simulations on the x-axis versus the MAP value from the CIGALEχ² analysis, for stellar mass M_*, mean mass-weighted stellar ages ⟨t_*⟩_m, SFR over the last 100 Myrs, stellar metallicity Z_* and the optical depths of the two-component dust attenuation model ${\widehat{\tau }}_{\lambda ,2}$ and ${\widehat{\tau }}_{\lambda ,1}$. The red points and errorbars show the median and standard deviation for several bins. Below each panel, we show mean the residuals and their standard deviations over ten bins covering the parameter range.