Russell on Gorman's Engel curves: A correction

Abstract

Russel [Economics Letters, 1983, 11, 223–224] claims to show that the main theorem in Gorman's ‘Some Engel curves’ [in A.S. Deaton, ed., Essays in the theory and measurement of consumer behavior, 1981 (Cambridge University Press, Cambridge)] follows from Lie's (1988) theory of transformation groups [Theorie der Transformationsgruppen (B.F. Teubner, Leipzig)]. That claim is incorrect, but Russell's argument can be used to prove a special case of Gorman's theorem.