Sector-Specific Substitution and the Effect of Sectoral Shocks
Jacob Toner Gosselin
TL;DR
The paper relaxes two restrictive assumptions in the literature on sectoral shock propagation by allowing sector-specific intermediate-input substitution elasticities ($\theta_i$) and by incorporating imports via the Armington elasticity ($\xi$), using BEA Input-Output Accounts to identify these parameters for 66 US industries. It shows substantial heterogeneity in $\theta_i$, with the uniform elasticity biased downward relative to the median sector-specific estimate, and demonstrates that this heterogeneity materially alters how shocks to import prices and sectoral productivity translate into price movements and GDP outcomes. Using a multi-sector GE model calibrated to the US, the study finds that sector-specific substitution amplifies oil-related price responses to oil-import shocks while dampening semiconductor-related responses, and that sector-specific elasticities increase the mean GDP impact of sectoral cycles by $0.35\%$, reducing the cost of sectoral fluctuations by about $17.7\%$. Overall, accounting for sectoral heterogeneity in substitution improves macroeconomic predictions and policy relevance by more accurately capturing the non-linear propagation of shocks through production networks.
Abstract
How a shock to an individual sector propagates to the prices of other sectors and aggregates to GDP depends on how easily sectoral goods can be substituted in production, which is determined by the intermediate input substitution elasticity. Past estimates of this parameter in the US have been restrictive: they have assumed a common elasticity across industries, and have ignored the use of imports in production. This paper uses a novel empirical strategy to produce new estimates without these restrictions, by exploiting variation in import ratios and input expenditure shares from the BEA Input-Output Accounts. I find that sectors differ meaningfully in their ability to substitute inputs in production, and that the uniform estimate of the intermediate input substitution elasticity is biased downwards relative to the median sector-specific estimate. Relative to imposing the uniform elasticity, sector-specific substitution causes domestic prices to rise more in response to oil import shocks and less in response to semiconductor import shocks. It also implies the average GDP response to a sectoral business cycle is 0.35% higher, making sectoral business cycles 17.7% less costly.
