The measurement of structural and exchange income mobility

Chakravarty, Dutta and Weymark (1985) present operational axioms for an ethical index of income mobility that are best suited for a two period world. This paper suggests a decomposition of this index into two terms: (i) an index of structural or snapshot mobility, which captures the welfare effect of differences in the inequality of the cross-section income distributions; and (ii) an index of exchange or rerankings mobility, which captures the welfare impact of rank reversals between the first- and the second-period income distributions. Income inequality reductions and rank reversals are always welfare enhancing. The properties of all the income mobility concepts introduced in the paper do not require any new value judgements beyond the traditional ones. Copyright Kluwer Academic Publishers 2004