Histograms of the difference between 12+log(O/H)_Nucl as estimated in the central regions using different photoionization models and 12+log(O/H)₀, as extrapolated from metallicity gradients. The step-filled gray histogram corresponds to all LINERs in our sample. The step blue and red histograms correspond to wAGNs and RGs, respectively. The vertical solid lines represent the median values for each distribution.