Cowell has shown that if an inequality measure satisfies (1) additivity, (2) decomposability (among population groups), (3) additivitiy of the group inequality measures, (4) symmetry within groups, and (5) twice differentiability, it can be written as an additive function of group measures belonging to the CES class or of the form ∑i, si, ln si, where si is the i-th person's share. Using a result from the theory of functional equations, I prove that the first two conditions, often imposed for analytical convenience, alone imply Cowell's structure. Symmetry, or other ethical postulates, can then be represented by simple parametric restrictions.

Journal Article Functional Separability and Partial Elasticities of Substitution Get access R. Robert Russell R. Robert Russell University of California, San Diego Search for other works by this author on: Oxford Academic Google Scholar The Review of Economic Studies, Volume 42, Issue 1, January 1975, Pages 79–85, https://doi.org/10.2307/2296821 Published: 01 January 1975

Charles Blackorby, R. Robert Russell; The Morishima Elasticity of Substitution; Symmetry, Constancy, Separability, and its Relationship to the Hicks and Al

Charles Blackorby, R. Robert Russell; Functional Structure and the Allen Partial Elasticities of Substitution: An Application of Duality Theory, The Review of E

policies have been in effect in the United States more than half the time. The Kennedy-Johnson wage-price guideposts lasted almost six years, although they were tattered and torn by the time they were abandoned in 1967. The Nixon Administration's Economic Stabilization Program (ESP)-the only peacetime mandatory controls program in the United States-lasted four years, although the second half of the program (Phases III and IV) was a period of decontrol. The Carter Administration's Pay and Price Standards Program lasted a little more than two years, although the second year was