Softness diagram and effective temperature and ionization parameter distributions in our samples. Left panel: softness diagram representing [O II]/[O III] vs. [S II]/[S III] for the selected regions in CHAOS and MaNGA as compared with different model sequences calculated using WM-Basic atmospheres for T_* between 30 and 60 kK (represented with circles), and Rauch for T_* between 80 and 120 kK (represented with squares). Solid lines represent models with 12 + log(O/H) = 8.9, and dashed lines 12 + log(O/H) = 8.0. Filled symbols represent models calculated assuming spherical geometry while empty symbols represent models with plane-parallel geometry (only for O/H = 8.9 in this case). Right panel: distributions of the derived properties using HCM-TEFF (upper panel: T_*, lower panel: log U) using as input the metallicity and the emission line-ratios represented in the left panel. The empty histograms represent the MaNGA sample and the orange ones the CHAOS sample. The median and standard deviations are represented in all panels in the same colors.