Histogram of the most relevant parameter in the RF when studying the residuals of the ΦZR (top panel) and the MZR (bottom panel) using 15 different estimators of Z_g (see Table A.1 for references). For the top panel, LW (MW) means light- (mass-)weighted and T95 (T99) represents the look-back time at which the galaxy has formed 95% (99%) of its mass. All of these attributes refer to different estimations of the stellar metallicity measured at 1 R_e.