Penn World Table, Center for International Comparisons, University of Pennsylvania

Penn World Table, Center for International Comparisons, University of Pennsylvania

The Penn World Table (PWT) displays a set of national accounts economic time series covering many countries. Its expenditure entries are denominated in a common set of prices in a common currency so that real quantity comparisons can be made, both between countries and over time. It also provides information about relative prices within and between countries, as well as demographic data and capital stock estimates. Since the regionalization of the ICP beginning with the 1980 benchmark, Summers and Heston at Penn have been using ICP benchmark comparisons (see About the ICP) as a basis for estimating PPPs for non-benchmark countries and extrapolations backward and forward in time.  These are the major components of Penn World Tables or PWT.  An early version of this technique was developed with Irving Kravis (1978): Kravis,I., R. Summers and A.Heston (1978). "Real GDP Per Capita for More Than One Hundred Countries," Economic Journal , June.
The Penn World Tables are described in Robert Summers and Alan Heston "The Penn World Table (Mark 5): An Expanded Set of International Comparisons, 1950-1988", Quarterly Journal of Economics, May 1991, pp.327--368. (See Research Papers) The table itself, an annex to the article, was distributed to users on a diskette and through anonymous ftp by the National Bureau of Economic Research in Cambridge, Massachusetts. A revised and updated version of PWT 5, PWT 5.5, was made available in 1993. Version 5.6 was released January 1995. It was prepared by Alan Heston and Robert Summers of the University of Pennsylvania, Daniel A. Nuxoll of the Virginia Polytechnic Institute, and Bettina Aten of the University of Illinois at Urbana-Champaign (now at the Bureau of Economic Analysis), with the research assistance of Valerie Mercer, James Walsh, and Bao Truong. The current version of Penn World Tables, PWT 6, is produced by The Center for International Comparisons at the University of Pennsylvania ( see About CIC ). PWT 6 has been prepared by Aten, Heston and Summers with the assistance of Mark McMullen, Feng Zhu, Sham Shah and  Prajesh Parekh. Robert Feenstra of the University of California, Davis, has been consulting with CICUP in preparing PWT 6 and will jointly produce subsequent versions through the Center for International Data at Davis, and in association with the NBER.
The Table contains data on about 30 variables for about 167 countries over some or all the years 1950-98.  As PWT 6 is modified these will be described in What is new? What is Different?   PWT is built up through a set of sophisticated extrapolations from the successive benchmark studies, both through time and across space. The Penn World Table is a forerunner of a new kind of international data base that may be described as a Space-Time System of National Accounts.  PWT 6 is comparable to previous versions of the table. However, the methodology of these comparisons is still being developed so that future versions may move in the direction of national accounts constant price series, namely chaining or use stochastic methods of aggregation.  While chaining over time is natural, in that time is sequential, chaining across countries does not have such an obvious path, which is why work along these lines has only been preliminary.
Using PWT
Many users of PWT 5.6 may want to refer to those files and documentation so they remain on this site.  The most obvious difference between PWT 5.6 and 6 is that the base year has been moved from 1985 to 1996.  A second difference, largely cosmetic, is that some of the variables have been renamed and the order has been slightly altered.  This should be clear in the list of variables for PWT 6.  As noted the present coverage is 1950-2000.  
In addition to the description of PWT cited above, there are two other pieces of documentation.  First, the data Appendix of PWT 5.6 may be consulted.  Second, we have created a more readable Data Appendix for PWT 6, with the treatment of China provided as a separate China Appendix.  Also, the national accounts file underlying PWT 6.1 is provided as a separate file in Downloads.

Penn World Table, Center for International Comparisons, University of Pennsylvania