sSFR plotted against M_star in logarithmic units (left panel) and 12 + log(O/H) (right) for the MAGMA sample. The heavy dark-gray curves correspond to the medians of the binned MAGMA data, and the underlying gray region to a standard deviation in either direction. The dark-gray plus signs report galaxies from the LVL sample as described in the text. The regression shown by the long-dashed line indicates the best (power-law) fit for the SFMS to MAGMA, as given by Eq. (1), and the short-dashed line to fit of LVL+KINGFISH galaxies as described in the text. The heavy dashed (red) curve corresponds to the [cubic in log(M_star)] SFMS found by Saintonge et al. (2016). Galaxies are color-coded by gas fraction (f_gas, here defined as M_gas/M_star) as indicated in the color wedge in the right-most panel.