Local metallicity at and around ±10 percent of the effective radius as a function of the global H I mass fraction for MaNGA (dark blue squares and arrows) and our sample (green circles), respectively. The numbers in the bottom left provide the Spearman correlation coefficient R and the number of galaxies used to calculated the statistic. For MaNGA we only used H I detections in the computation of R. The yellow and red line show our model for different ratios of H I to stellar radius, namely, 3.3 and 5.6, respectively. The underlying model of the dashed lines assumes an effective yield of 0.00268 (Pilyugin et al. 2004) and the dotted lines a stellar yield of 0.037 (Vincenzo et al. 2016 and references therein). We note that we use the M13 O3N2 calibration in this figure.