Market Integration: An Application to International Trade in Cotton
提出两种价格关联检验方法，用于判断差异化农产品能否视为同质商品，并以国际棉花市场为例，发现纤维长度是关键区分因素，原产国影响不大。
Abstract Agricultural commodities are differentiated frequently by quality or country of origin. This paper proposes two complementary tests—bivariate price regressions and hedonic index estimation—as methods to identify whether differentiated products are amenable to treatment as a homogenous commodity. These price linkage tests represent necessary, rather than sufficient, conditions for aggregation and must be supplemented by information on market structure. Analysis of the international cotton market suggests a distinction between extra long and other staple lengths, but not by country of origin after controlling for staple length.