Understanding PPPs and PPP-based National Accounts: Comment
评论了如何选择指数公式进行跨国实际产出比较，指出国际比较项目（ICP）依赖的国民支出数据存在不准确和不一致问题，且难以比较发展水平悬殊国家的实际产出。
How exactly should we choose an index number formula that will enable us to compare real outputs across countries? Index number comparisons between countries require information on the prices of products in the same units of measurement and information on expenditure shares by product category. The ICP gets expenditure shares using information on final demand expenditures from the national accounts of the participating countries. However, these national expenditure estimates are not very accu rate in some cases, and are not always constructed on a consistent basis across countries. It is very difficult or impossible to compare real outputs across countries at very different stages of development, since poor countries may consume products which are very different from the products consumed in rich countries (i.e., it is impossible to compare the incomparable).