Probability distribution function for the c₁ (left column) and c₂ (middle column) coefficients of the generalized mass–metallicity relation in the center of galaxies (top panels), at R = 0.5R₂₅ (middle panels), and R = R₂₅ (bottom panels). The solid vertical line represents the zero value for each coefficient. The right column represents the correlation between the c₁ and c₂ coefficients.