Nonhomotheticity and Bilateral Trade: Evidence and a Quantitative Explanation
研究发现双边贸易对人均收入反应强烈而对人口规模不敏感，通过构建允许贸易弹性随人均收入和人口分化的李嘉图模型，利用162国数据估计，改进了引力模型的预测，并模拟了中国技术冲击对不同收入国家的影响。
The standard gravity model predicts that trade flows increase in proportion to importer and exporter total income, regardless of how income is divided into income per capita and population. Bilateral trade data, however, show that trade grows strongly with income per capita and is largely unresponsive to population. I develop a general equilibrium Ricardian model of trade that allows the elasticity of trade with respect to income per capita and with respect to population to diverge. Goods are of various types, which differ in their income elasticity of demand and in the extent to which there is heterogeneity in their production technologies. I estimate the model using bilateral trade data of 162 countries and compare it to a special case that delivers the gravity equation. The general model improves the restricted model's predictions regarding variations in trade due to size and income. I experiment with counterfactuals. A positive technology shock in China makes poor and rich countries better off and middle-income countries worse off.