统计研究 ›› 2018, Vol. 35 ›› Issue (9): 16-28.doi: 10.19343/j.cnki.11-1302/c.2018.09.002

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国际比较项目中的中国PPP偏差问题

向书坚 李凯   

  • 出版日期:2018-09-25 发布日期:2018-09-25

Deviation of China’s PPP in the International Comparison Program

Xiang Shujian & Li Kai   

  • Online:2018-09-25 Published:2018-09-25

摘要: 2014年世界银行公布的2011年轮全球国际比较项目(ICP)测算结果与发展中国家真实经济规模存在偏差,引发了发展中国家购买力平价是否被系统性低估的疑问。为此,基于ICP中中国部分的测算结果,立足于国际比较项目支出法测算的角度,对中国PPP偏差问题进行了分析。分析认为,从理论上看,ICP要求参与国提供GDP支出项数据与规格品价格数据在大国内部受到 了市场分割的影响,识别这种分割程度即空间关联性是ICP数据调查的前提。基于空间计量模型的实证结果表明:①在ICP的第七轮与第八轮调查期内,中国内部市场分割导致了价格水平存在时空两个方面的差异,影响了中国PPP计算的准确性;②市场分割导致的中国各地区的价差在短期内呈现随机性,只有长期才有可能出现趋同性。但2017年轮ICP调查周期由6年缩短为3年,使得这种趋同性难以出现在ICP活动的调查期内;③虽然ICP2017年轮采用滚动基期计算PPP,仍无法涵盖中国分割市场各自支出项目在空间上的不同作用力,这会使得支出法角度测算PPP时依然不能完全消除它的偏差,需要根据不同规格品的归属赋予不同权重才能较好地提高PPP测算的准确性。

关键词: 国际比较项目, 价格水平差异, 购买力平价, 空间回归分析

Abstract: There was a deviation of the measurement results from the report of 2011 World International Comparison Program (ICP) published in 20014 by the World Bank in comparison with the real economic scale of the developing economies. It triggered doubts on whether the purchasing power parity (PPP) was systematically underestimated in the developing economies. Therefore, based on the measurements of the ICP of China and the expenditure method of the global ICP, an analysis was undertaken on the issues of deviation of China’s PPP. The results show in theory, the data on GDP expenditure and the price data for standard items that are required by ICP provided by the participating countries are influenced by the segmentation of the markets within a large country. It is a prerequisite to identify the degree of segmentation of the markets, i.e., spatial association, for ICP surveys. The empirical results based on the spatial econometric models further show that: (i) In the seventh and eighth rounds of the ICP surveys, the segmentation of China’s internal markets led to the existence of spatial and temporal differences in price levels, that largely reduced the accuracy of PPP calculation in China; (ii) The market segmentation resulted in the randomness of the price discrepancy in various regions of China in the short term, and only possible to have convergence in the long term. However, the frequency of ICP survey in 2017 was reduced from 6 years to 3 years in 2017, making this convergence hard to occur in the ICP survey period; (iii) ICP 2017 adopted the rolling reference period to calculate PPP, but this change cannot spatially cover the differing forcing effects of the expenditure items in China’s segmented markets. So it would not be possible to reduce the bias in the calculation by even using the PPP estimation. Only based on different weights attributed to where the items comes from can we improve the accuracy of PPP estimation

Key words: International Comparison Program, Price Level Difference, Purchasing Power Parity, Spatial Regression Analysis