The Structure of Consumer Demand: The Expenditure System of the CDES Indirect Utility Function: Part I - II : Theory and Application

In this paper, we unify and extend the analytical and empirical application of the ”indirect addilog” expenditure system, introduced by Leser (1941), SomermeyerWit (1956) and Houthakker (1960). Using the Box-Cox transform, we present a parametric analysis of the Houthakker specification of the fundamental indirect utility function - called the CDES specification (constant differences of Allen elasticities of substitution) by Hanoch (1975). It is shown that the CDES demand system is less restrictive than implied by standard parameter restrictions in the literature, Hanoch (1975), Deaton & Muellbauer (1980), Houthakker (1960), Silberberg & Suen (2001). Our parametric extension implies that Marshallian own-price elasticities are no longer restricted to being all larger than one in absolute value; hence CDES can now naturally exhibit both the inelastic and elastic own price elasticities of observable (Marshallian) demands. Furthermore, we argue that in computable general equilibrium models (CGE), the CDES compares favorably with other expenditure systems, e.g. the linear expenditure system (LES), since CDES and LES need the same outside information for calibration of the parameters, but CDES is not confined to constancy of marginal budget shares (linear Engel curves). Moreover, we show that the non-homothetic CDES preferences are a simple and natural extension of the homothetic CES (constant elasticities of substitution) preferences, and, accordingly, CDES can more realistically be used in specifying CGE models with a demand side of non-unitary income elasticities. A succint theoretical briefing of the CDES history with general and concise formulas is offered. We illustrate CDES estimation and the calculation of a comprehensive set of income and price elasticities by applying CDES to Danish budget survey data. With a large number budget items included, coherent numerical values for the income, own, and cross price elasticities, as shown here, seem nowhere calculated and available in the voluminous literature.