Across-Product Versus Within-Product Specialization in International Trade
利用美国产品级进口数据检验贸易理论，发现美国从高工资和低工资国家进口相同产品，但产品内单位价值随出口国要素禀赋和技术差异而变化，这否定了跨产品专业化，支持产品内专业化，对理解全球化影响和收入趋同有重要意义。
This paper exploits product-level U. S. import data to test trade theory. Although the United States increasingly sources the same products from both high- and low-wage countries, unit values within products vary systematically with exporter relative factor endowments and exporter production techniques. These facts reject factor-proportions specialization across products but are consistent with such specialization within products. The data are inconsistent with new trade theory models predicting an inverse relationship between price and producer productivity. The existence of within-product specialization is an important consideration for understanding the impact of globalization on firms and workers, the evolution of total factor productivity, and the likelihood of long-run income convergence.