Left panel: Histogram of the gas extinction obtained via Balmer decrement for the INT (in red) and CTR sample galaxies (in blue). The mean and median values of both samples as in Fig. 11. Right panel: Relation between stellar extinction ($A_V^{\star }$) and nebular extinction ($A_V^{\mathrm{gas}}$) for the INT (red circles) and CTR (blue triangles) samples. Dashed lines show the best linear regression fit obtained in both cases. The linear equations, Pearson correlation coefficients (r-value), and p-values of the fits are indicated in the inset. The dotted gray line corresponds to the case in which $A_V^{\mathrm{gas}}$ = $A_V^{\star }$.