The PDFs for optical depth in the V band, the gas-phase oxygen abundance, the logarithm of the ionization parameter, log₁₀ of the conversion factor from the observed Hα luminosity to SFR, the logarithm of the gas surface density in M_⊙舁pc⁻², the log of the DGR and the metal-to-gas ratio. From one row to the next, we include the line indicated on the left side in the fitting in addition to the previous emission lines. For the observational data in this figure, we make use of emission line fluxes measured by DZ11, from their table 2, for image A3 (see Fig. 1). Our best-fitting parameters and the associated 16th and 84th percentiles are summarized in Table 5. The abundance of oxygen reported by DZ11 is lower than what we find.