From relative prices to real import and export volumes The final step in the process is from the relative price of imports and exports to the volumes of real imports and exports. This depends on the elasticity of the demands for imports and exports with respect to their relative prices and the size of trade flows relative to GDP.
The elasticities of imports and exports with respect to their respective relative prices are estimated to be about unity, and there is no evidence of a shift in this elasticity over the past several decades.