Income-(in)dependent equivalence scales and inequality measurement

Abstract Most equivalence scales that are applied in research on inequality do not depend on income, even though there is strong empirical evidence that equivalence scales are actually income-dependent. This paper explores the consistency of results derived from income-independent and income-dependent scales. We show that applying income-independent scales when income-dependent scales would be appropriate leads to violations of the transfer principle. Surprisingly, there are some exceptions, but these require unrealistic and strong assumptions. Thus, the use of income-dependent equivalence scales almost always leads to different assessments of inequality than the use of income-independent equivalence scales. Two examples illustrate our findings.