PhD ThesisThe soybean industry is an interesting area for investiga- It is extremely complex and has been changing rather t ion. dramatically over the last 10 to 15 years. There exists a high degree of interaction among the markets for soybeans, oil and soybean meal. soybean Recent shocks and changes in the world economic environment have impacted substantially on the industry altering the demand for its products and even changing the participants and their roles in the marketplace. Understanding the behavior of the soybean industry is important to market participants, alike. producers and consumers Changes in market structure can influence demand and supply conditions, price movements and can cause rather consid- erable changes in farmer income and the prices that consumers pay for related final products. Under these circumstances, the value of accurate forecasting of prices and quantities increases in importance. ters (e.g. Also, knowledge of changing structural parame­ elasticities) can be crucial to government decision­ makers in analyzing the effects of alternative farm policies. The general thrust of this thesis involves the econometric modeling of structural change in the U.S. products markets. soybean and soybean A quarterly econometric model is specifiedV within the framework of a systematic varying coefficients simultaneous system. Changing parameters will be identified and an examination of the forecasting performance of the model will be made.