Decomposition of s ― Concentration Curves

For any given order of stochastic dominance, standard concentration curves are decomposed into contribution curves corresponding to within-group inequalities, between-group inequalities, and transvariational inequalities. We prove, for all orders, that contribution curve dominance implies systematically welfare-improving tax reforms and conversely. Accordingly, we point out some undesirable fiscal reforms since a welfare expansion may be costly in terms of particular inequalities.