SFR and L_[OIII]5007 ratio vs the ionization parameter. Each metallicity bin is presented as blue dots, orange squares, and green triangles. The ionization parameter is computed with CIGALE for each fixed metallicity case. The black dashed line corresponds to the −41.20 [M_⊙ yr⁻¹erg⁻¹ s] intercept found in Eq. (6). The symbols with errors represent the median values of the SFR/L_[OIII]5007 ratio for each metallicity. The ionization parameter has a larger impact on the dispersion than the gas-phase metallicity.