Geographic Markets, Causality and Railroad Deregulation
提出用瞬时因果关系定义市场的方法，并应用于1979-1982年美国面粉市场，发现铁路放松管制后城市间价格关联增强，市场是全国性的。
This paper presents an approach to defining a market using the notion of instantaneous causality. The market for which the approach is empirically implemented is the flour market in the United States over the period January 1979 through October 1982. One anomaly over this period was the deregulation of railroad rates in October 1980. The empirical results based on three spatially diffuse cities suggest that the market is national in scope and that after railroad deregulation the price interrelationship between cities was strengthened.