Since the mid-1970s, there has been a fundamental structural change in the way that agricultural economists view the macroeconomic sector. This change began with Schuh, who pointed out the importance of exchange rates on farm prices and argued for the need to examine the agricultural sector in the context of an open world economy. Chambers and Just subsequently developed a structural econometric model for the U.S. crop sector and found significant exchange rate impacts on agricultural exports and prices. Barnett, Bessler, and Thompson constructed a reduced-form vector autoregression (VAR) model and identified a Granger-type causal relationship running from U.S. money supply to agricultural prices.