International Trade and Income Differences
提出富国与穷国之间的贸易摩擦存在系统性不对称，穷国出口成本更高，并论证这种摩擦对理解各国生活水平和生产率差异有重要影响。
I develop a novel view of the trade frictions between rich and poor countries by arguing that to reconcile bilateral trade volumes and price data within a standard gravity model, the trade frictions between rich and poor countries must be systematically asymmetric, with poor countries facing higher costs to export relative to rich countries. I provide a method to model these asymmetries and demonstrate the merits of my approach relative to alternatives in the trade literature. I then argue that these trade frictions are quantitatively important to understanding the large differences in standards of living and total factor productivity across countries.