Proximity and Production Fragmentation
利用1970-2009年总值和增加值贸易数据，发现跨境生产链倾向于邻近国家，增加值出口比率在区域内更低且下降更快，总值贸易比增加值贸易距离更短且差距随时间扩大。
Cross-border production chains tend to include geographically proximate countries. This suggests that increases in fragmentation should be largest among nearby trading partners, and thus may serve to localize gross trade. Using data on gross and value added trade from 1970-2009, we present three results supporting this conjecture. First, value added to export ratios are lower and falling more rapidly within geographic regions than between them. Second, gross trade travels shorter distances from source to destination than value added trade, and this gap is growing over time. Third, bilateral value added to export ratios have fallen most among nearby trading partners.