Left: change in the outer-disk color gradient as a function of the galaxy stellar mass, as derived by Walcher et al. (2014), along with the linear fits to the values derived for the Tii (cyan solid line) and Tiii-type (green solid line) galaxies. The p-value parameters in this case range between 0.1 and 0.2, although the dichotomy between Tii and Tiii at low stellar masses is quite clear. Right: the same as above but for the change in ionized-gas metallicity gradient. The correlation in the case of the Tii galaxies yields very low p-values, namely 0.003 (Pearson), 0.018 (Spearman), and 0.010 (Kendall), indicating that stellar mass might be one of the main drivers of the change in the ionized-gas metallicity in the outer disk of Tii galaxies.