A question of considerable policy relevance is to what extent changes can be attributed to direct policy action or to other factors that are not amenable to influence by policy makers. Since tax burdens and benefit entitlements depend on incomes and population characteristics, a given tax-benefit system can become more or less effective at reducing inequalities, even if policy rules remain unchanged. For instance, when unemployment goes up, measured redistribution is likely to increase even with constant benefit amounts per job seeker, simply because more people claim unemployment benefits. Similarly, a progressive income tax will redistribute more if taxable incomes become more dispersed (or very little if everybody earns about the same).