Primal/dual positive math programming: Illustrated through an evaluation of the impacts of market resistance to genetically modified grains

The goal of Howitt's positive mathematical programming procedure is to calibrate a mathematical programming model so that it will reproduce a set of base data for the primal variables. This article develops an analogous procedure allowing one to specify the levels of both primal and dual variables. The article also shed light on a potential ambiguity of Howitt's procedure (with attendant policy evaluation impacts). The procedure is illustrated through application to an equilibrium displacement model focused on evaluating the consequences of the reluctance of US trading partners to accept genetically modified crop products for US production patterns and net farm income.