A model of price and quantity adjustments in primary commodity markets

Abstract

This paper presents a dynamic, simultaneous model of price and quantity adjustments in world primary commodity markets. The model is formulated in a disequilibrium framework, emphasizing particularly the role of price adjustment. In addition to the price equation, commodity consumption and production equations are also specified. The empirical analysis of the model is carried out with the annual data of six primary commodities: coffee, cocoa, rubber, copper, tin, and sugar. This includes the estimation of price, consumption, production equations, the simulation tests of complete structural models for these six commodities, and the derivation of dynamic responses (measured by elasticities) of commodity prices to changes in world income, world inflation, and commodity outputs. Dynamic simulations strongly confirm the commonly observed self-generating and recurring boom-and-bust cycles of primary commodity prices. This finding lends credibility to the models constructed.