Observed values of 12 + log(O/H) in the MAGMA sample compared to those predicted by the 3DPCA²(OH) given in Eq. (5). The parent sample of the individual MAGMA galaxies is given in the legend in the middle panel, and the right panel shows the residuals and the Gaussian fit; the 1σ dispersion of the Gaussian is 0.074 dex as discussed in the text. The MAGMA 3DPCA²(OH) applied to SDSS10 is also shown, and as before 90% of SDSS10 is enclosed within the contours. The median of the SDSS10 residuals relative to the 3DPCA²(OH) is 0.002 dex, with a standard deviation of ∼0.08 dex, showing that even when the MZR curvature is clearly evident in SDSS10, the MAGMA 3DPCA²(OH) does a good job of reproducing the metallicities (see text for more details).