Provision of regional input-output tables by the use of information obtained through census methods, in addition to imposing excessive costs on planning apparatus, imposes time constraints on the realization of regional development plan objectives in due time. Moreover, the use of sample surveys at the regional level, may lead to high inaccuracy due to limited number of observations.
One of the more common approaches in obtaining regional input-output tables with much less expenses and time, is the GRIT methodology, which uses the national input-output table as the base and then make necessary adjustments for: 1) the change inprices with respect to time and location and 2) the differences between the pattern of a country's foreign trade and the regional trade within the country's territory. These adjustments lead primarily to a mechanically-produced table of regional inter-industry transactions. In further steps, recent "superior data" is to be used to adjust the technical coefficients in that table, based on their degree of importance.
It is evident that construction of such regional tables, as appropriate planning tools, is important and as such, construction of this table for the province of Isfahan in Iran was undertaken. The aim of this article is mainly an attempt to summarize and briefly present the GRIT methodology of obtaining regional input-output tables, describe its strengths and weaknesses and discuss the summary results of its application to the region of Isfahan in Iran.