The Aggregate Importance of Intermediate Input Substitutability

Should economic development policies target specific sectors of the economy or follow a 'big push' approach of advancing all sectors together? The relative success of these strategies is determined by how easily firms can substitute between intermediate inputs sourced from different sectors of the economy: a low degree of substitutability increases the costs from 'bottleneck' sectors and the need for 'big push' policies. In this paper, we estimate long-run elasticities of substitution between intermediate inputs used by Indian manufacturing plants. We use detailed data on plant-level intermediate input expenditures, and exploit reductions in import tariffs as plausibly exogenous shocks to domestic intermediate input prices. We find a long-run plant-level elasticity of substitution of 4.3, much higher substitutability than existing short-run estimates or the Cobb-Douglas benchmark. To quantify the aggregate importance of intermediate input substitution, we embed our elasticities in a general equilibrium model with heterogeneous firms, calibrated to plant- and sector-level data for the Indian economy. We find that the aggregate gains from a 50% productivity increase in any one Indian manufacturing sector are on average 47% larger with our estimated elasticities. Our counterfactual exercises highlight the importance of intermediate input substitution in amplifying policy reforms targeting individual sectors.