Redistributive Effects of Tax Progressivity: Evaluating a General Class of Aggregate Measures

Based on an explicit definition of the object of measurement, a general class of aggregate measures is introduced. It is defined as the weighted sum of the deviations of taxes, or post-tax income, from yield-equivalent proportionality. The widely used Kakwani and Suits indexes and some other "new" measures are shown to be but particular members of this class. Then the question is addressed as to what particular measure of this class should preferably be used in case of inconsistent rankings. The answer is an axiomatic and multidimensional approach to the measurement of redistributive effects.