Observed PS, the best-fit PS, and the envelope of the PS simulations where all parameters are in the 25% confidence interval (light green) and 68% confidence interval (light grey) for the first eight SFG for which an Hα + [N II] line is detected. Violet, blue, and cyan vertical lines in the PS figures show the position of the [N II]λ6548, Hα, and [N II]λ6583 line, respectively, for the best z obtained in by the fit. The red points that appear in some observed PS were removed during the fitting process because they correspond to the [S II]λλ6716,6731 doublet or may be artefacts. To the right of each PS is the PDF of 12 + log(O/H) that was obtained from the Monte Carlo simulations where the mode (our reference value), the 25%, 68%, and 90% confidence intervals around the mode are shown as vertical lines; the black vertical line in these plots shows the empirical division between SFR and AGN at 12 + log(O/H) = 8.67 (N2 = −0.4).