Incorporating Policy Variables in a Model of the World Soybean/Rapeseed Market

Policy variables are typically treated as exogenous variables in agricultural commodity models. In this paper evidence that policy variables can be successfully endogenized in a world trade model of the soybean/rapeseed and products market is presented. Minimum price support equations are estimated for U.S., Brazilian, and Japanese soybeans, and EC and Japanese rapeseed. Macroeconomic indicator variables are used to capture the impact of nontariff barriers in Brazil and Japan domestic‐world price link equations. Simulation experiments are conducted which indicate that the model with endogenous policy variables performs well in comparison with a model which treats policy exogenously.