A time-series analysis of Zimbabwe's corn sales to the Grain Marketing Board

This article considers methods of cointegration testing to construct a model of Zimbabwe 's corn sector. Corn production, sales of corn to the government, the price of corn, and price of beef are linked together in one long-run equilibrium (cointegrating) relation. Only the price of beef is not weakly exogenous to perturbations in this relation. That is to say, when these variables are out of long-run equilibrium, it is through subsequent changes in the price of beef that equilibrium is restored. The other variables do not respond to a long-run disequilibrium. Short-run forecasts from this model are compared with expert opinion forecasts made by the government's marketing board. Possibilities for improvement in long-run forecasting and planning are discussed.