Team research has been much more widespread in the natural sciences than in economics. Yet when it comes to modeling an economy (especially the global economy) in detail, the quantity and range of inputs necessary makes team work the only viable option. Drawing some inspiration from Australian experience, GTAP's founder, Tom Hertel, realized this from his Project's inception in 1993. The data base required to model international trade flows could not have been developed without the enthusiastic cooperation of many individuals and institutions around the world. Funding GTAP's central team at Purdue required external support. National agencies in Australia, Denmark, France, Germany, Holland, Japan, and the US are members of the supporting research consortium. The natural interest of international economic agencies led to GTAP having five such supporting agencies by 1997, which grew to ten by 2006. GTAP has striven to put the maximum feasible amount of its data, methodology and models into the public domain. It has run numerous residential intensive training courses in the use of the GTAP data and model: these have been held in the US, Europe, Africa, Asia and Latin America. The success of these courses reflects the modeling experience of the teams of course instructors and the availability of special-purpose software which allows simulations to be run without programming skill or previous knowledge of the software used. Researchers making use of GTAP have been prolific in number, and in their output. In mid April 2007, applications listed on the GTAP web site numbered 781. There were 366 subscribers to the GTAP data base at the end of April 2007, but the number of individuals making use of GTAP data exceeded 4,000. A web search using Google Scholar for the 1997 GTAP monograph records more than 1,150 citations, while versions 3 and 5 of GTAP's data base are cited 279 and 389 times respectively. It is clear that GTAP has engendered a community of quantitatively-oriented trade economists, and has integrated their efforts with those of other economists having an economy-wide perspective, especially those working on economic development. GTAP's success as a policy tool has led to an ever increasing demand for its extension to cover more commodities, regions, and economic issues: international migration of labor and climate change, for instance. With the current level of financial support, such expansions to GTAP's range are possible only on a limited scale.
