关键词: 产品差异化, 替代弹性, 进口价格指数, 贸易利益

Abstract: Product diversification is an important source for a country`s gains from import trade, while the objectivity of estimation results for the gains is determined by the degree of trade data classification. By making use of China`s bilateral HS8 import data with more than 240 countries, this paper evaluates the elasticity of substitution for 4236 products, obtaining the average elasticity of substitution of differentiated products is 43.1 and the median is 7.6. Comparing with 2000, in 2011 disappeared product categories account for 1.4%, those newly emerged account for 4.3%, and the net growth of differentiated product categories is 1.5%. The actual import price index is 1.5% lower than the traditional one which is not adjusted with variety change and China`s gains from import variety from 2000 to 2011 is about 0.56 % of GDP in 2011. It is found that those studies on China`s gains from import variety using rough trade data have underestimated the elasticity value, the degree of change and the welfare effect of import variety. Furthermore, our study shows that increasing the trade volume of new product categories should be attached more importance to improve China`s import diversification. To improve the China's gains from import, some products can be selected as the focus for import variety growth.

Key words: Product Differentiation, Elasticity of Substitution, Import Price Index, Gains from Trade