The implications of using different measures of tax progressivity have, however, not been sufficiently addressed. In this project we intend to explore the implications of using different measures of tax progressivity by ranking various countries in terms of redistributive effects. Lambert and Thoresen (2005) found, when applying the Blackorby and Donaldson (1984) index of tax progressivity, based on the Atkinson index of income inequality, that the Norwegian tax system is not that redistributive. This mig ht be surprising given the perception of Scandinavian economies being very redistributive.However, this result is perfectly intuitive given the cost of proportional taxation concept of the Blackorby-Donaldson index: it measures the proportion of after-tax income the social decision maker would hypothetically pay to convert a flat tax system into the given one.
A main point here is that results of cross-national comparisons will not be independent of which measure is employed. There are reasons to expect differing results, dependent on the choice of index. In this work, the authors will explore thoroughly the normative underpinning of all measures in the literature, in order to determine the meaningfulness of derived rankings and provide some recommendat ions for the practitioners. Moreover, we hope in this way to arrive at a full appreciation of Norway's place in the world of international tax systems.
Thus, this project aims at answering two questions: Firstly, it examines to what extent international rankings depend on choice of measure, which is important information for practitioners. Secondly, it enables a much more informed discussion of Norwegian tax redistribution, in an international setting.