Relation between X_neb and the different tracers considered in this work: EW of Hα (upper left), EW of Hβ (upper middle), sSFR (upper right), sum of the flux of the most prominent emission lines (lower left) and SFR (lower right). In the upper left of each panel, we present the Pearson correlation coefficient assuming a linear fit to the data. For the selected best tracers of X_neb, the red line is the derived best linear fit and the resulting equation is presented in the legend. The median error of the data is presented in the bottom right corner. The axes are in logarithmic scale.