【题 目】Decomposing Change in Gains from Trade under Fragmentation
樊海潮，复旦大学经济学院教授，博导，复旦大学世界经济研究所副所长。学术成果发表在Review of Economics and Statistics、Journal of International Economics、Economic Journal、Journal of Development Economics, 《经济研究》、《管理世界》等国内外学术期刊上。现任Review of International Economics、Journal of Economic Survey、Economic Modelling副主编，世界经济文汇责任编辑，以及多个杂志的特刊主编。
We modify the Eaton and Kortum (2002) model to a multi-sector general equilibrium Ricardian model with fragmentation and input-output linkages. After calibrating the model, we carry out counterfactual exercises to quantify the impacts of the changes in the exogenous variables on gains from trade (GFT) of countries, and carry out variance decomposition to quantify the contribution of each factor. Then, we carry out some policy counterfactuals. The results are: 1.Global changes in trade costs and technology stocks explain about 97% of the variance of the changes in GFT of nations. 2.The estimated change in GFT from a model that takes into account fragmentation is on average 53% higher than that estimated by a model that does not. 3.The average elasticity of GFT w.r.t. domestic changes in technology stocks (trade costs) in intermediate goods is three (two) times that of domestic changes in final goods technology (trade costs). 4.International spillovers contributed to 65% of the changes in domestic GFT of countries. 5.Export-biased technological changes accounted for 48% of the increases in domestic GFT of nations. 6.Heat maps showing friends and enemies in international trade indicates that China has most friends. It accounts for 31% of total international spillovers from all countries.