This variability underlines the importance of considering the possibility of shifting preferences, particularly in a cross-country comparison of trends in redistribution policies and indicators. For middle and higher income ranges, the difference is likely to be small, as ranking by gross and net incomes can be expected to result in similar groupings. For the bottom quintile, however, the tax-benefit system is likely to result in re-ranking (for instance, a considerable number of households with zero or very low incomes may be entitled to significant amounts of benefits and may therefore not be classified in the low-income group according to household disposable income).