Integrating information from national SAMs into a dis-aggregated GTAP Data Base

We detail an approach to update country specific data in a (dis)aggregated GTAP Data Base, starting from a single country SAMs. Whereas data contributors to the GTAP Data Base deliver country specific IO-tables to the GTAP for inclusion in the build process of the GTAP Data Base, our approach starts from the given GTAP Data Base and updates macro totals, output, intermediate and final demand, imports and exports by product, tax rates etc. for the specific country, in order to keep as much information as possible from the available national SAM. The process is based on four steps. We first derive a GTAP Data set by aggregation, which comprises a single country and typically one Rest-Of-the-World aggregate, with products and sectors aggregated, such as to match as closely as possible the detail of the national SAM. If deemed useful and if data for the Rest-Of-the-World are available, we split the GTAP data to a finer product and sector detail. Second, we derive preliminary estimates at the country level, for the relevant aggregates in GTAP (demand of agents for imports and domestic production at market and agent prices, factor demands etc.). Third, we balance the resulting data, such as to match the values for the given single country SAM at its sector/product level, keeping consistency, for instance, regarding exhaustion conditions and market balancing. Fourth, the balanced single country data overwrite the given GTAP original data, and the whole framework is balanced again.