Collaborative Proposal: Integrating Expenditure and Production Estimates in International Comparisons

我们的研究领域之一，承诺作出重大贡献的概念和方法问题，在使用单位价值，使价格和购买力平价（PPP）比较各国。 国际贸易和生产数据通常用来估算价格，方法是将生产、出口或进口的类别的价值除以其各自的数量。 数量本身是在一个相当详细的水平，但仍然是异质的，往往梳理说，不同容量和/或不同质量的泵到一个数量。 概念上的问题是，我们不知道在某些国家，价格是否会因为物品的数量和/或质量较低而较低。 这项研究通过使用详细的海关数据同时研究各国对更高质量物品的需求和供应来解决贸易数据的这一问题。 由加州大学戴维斯分校国际数据中心开发的初步结果表明，这是一个令人兴奋的方法来解决一个问题，这是使用单位价值贸易数据的基础。 此外，基础数据集对该领域的研究人员也很有价值，这项研究的另一个非常重要的方向是使用购买力平价在一致的基础上整合生产和支出方面的估计数。 到目前为止，比较容易进行的支出方面的比较涵盖了180多个国家1950年至2004年的部分或全部年份，是宾夕法尼亚大学世界表的一部分。 然而，这些估计只能对GDP水平的生产率进行近似比较，而最感兴趣的是零售业和IT等部门。在国内总产值一级，上述单位价值研究所产生的贸易条件的调整，使各国总生产的估计有了很大的改进。 格罗宁根增长和发展中心对许多国家的生产部门进行了比较。 我们的目标是将GGDC的估计数与PWT中尽可能多的国家的估计数联系起来，这将在方法上以及对各国生产率的比较方面做出重大贡献，从而使该项目产生重大的全球研究影响。随着上述研究的进展，我们希望在国际比较中进一步缩小贸易、支出和生产流量之间的循环。 这方面的一个主要障碍是，一国进入国际贸易的商品价格往往与该国生产的商品价格大不相同。 因此，即使人们通过比较出口和进口的价格来解决国家间的质量问题，这也不一定会产生与国内生产比较相同的两个国家之间的比较。 像中国这样的国家，出口各种高质量的产品，也生产这些产品的国内版本，质量较低，不同的组合。 这一重要问题将是作为该项目一部分计划举办的讲习班的一个主要议题，世界银行正在协调2005年国际比较项目最新详细基准比较。 将这些估计纳入PWT将是这一广泛使用的数据集的重大升级的一部分。 这将是一个机会，可以介绍作为正在进行的研究的一部分而出现的一些方法上的变化，有些是由我们的合作项目的成员作出的，有些是由独立研究人员作出的，有些是在编写比较方案手册时作出的。

One area of our research promises to make a major contribution to conceptual and methodological problems in the use of unit values to make price and purchasing power parity (PPP) comparisons across countries. International trade and production data are often used to approximate prices by dividing values of categories produced, exported or imported by their respective quantities. The quantities themselves are at a fairly detailed level but still are heterogeneous, often combing say, pumps of different capacities and/or different qualities into one quantity. The conceptual issue is we do not know if the prices may be lower in some countries because of the mix of items in the quantity and/or the lower quality of the goods. The research tackles this problem for trade data by simultaneously looking at the demand and supply of higher quality items by country using detailed customs data. Preliminary results developed by the Center for International Data at the University of California/Davis suggest this is an exciting approach to a problem that is fundamental to the use of unit value trade data. In addition, the underlying data sets will be of value to researchers in the area.Another very important direction of this research is related to the integration of production and expenditure side estimates on a consistent basis using PPPs. Up until now expenditure side comparisons, which are simpler to carry out, cover over 180 countries for some or all the years 1950 to 2004 as part of the Penn World Table (PWT). However, these estimates only allow approximate comparisons of productivity at the GDP level, whereas most interest attaches to sectors like retail trade, IT, and the like. At the GDP level, the adjustments of the terms of trade that flow from the unit value research described above permit very much improved estimates of aggregate production across countries. Comparisons of productive sectors have been carried out by Groningen Growth and Development Center (GGDC) for a significant number of countries. It is our goal to link the GGDC estimates to those of as many countries as possible in PWT, which would be a major contribution both methodologically as well as for comparisons of productivity across countries, thereby giving this project a major global research impact.As the above research progresses we hope to formulate a further closing of the circle between trade, expenditure and production flows in international comparisons. A major hurdle here is that the prices of goods entering international trade of a country are often quite different from the prices of goods produced in a country. So even if one has solved the quality program across countries in terms of comparing prices of exports and imports, this will not necessarily produce the same comparison between two countries as would a comparison of domestic production. A country like China, which exports a variety of high quality products, also produces domestic versions of those items of lower quality and different mix. This important issue will be a major subject of the workshops planned as part of this project.The latest detailed benchmark International Comparison Project (ICP) comparisons for 2005 are being coordinated by the World Bank. Integration of these estimates into PWT will be part of a major upgrade of this widely-used data set. It will be an opportunity to introduce a number of methodological changes that have emerged as part of ongoing research, some by members of our collaborative project, some by independent researchers, and some developed in conjunction with the preparation of an ICP handbook.