An Instrumental Variable Approach to Dynamic Models
Steven T Berry , Giovanni Compiani, An Instrumental Variable Approach to Dynamic Models, The Review of Economic Studies, Volume 90, Issue 4, July 2023, Pages 1724–1758, https://doi.org/10.1093/restud/rdac061
We present a new class of methods for identification and inference in dynamic models with serially correlated unobservables, which typically imply that state variables are econometrically endogenous. In the context of Industrial Organization, these state variables often reflect econometrically endogenous market structure. We propose the use of Generalized Instrument Variables methods to identify those dynamic policy functions that are consistent with instrumental variable (IV) restrictions. Extending popular “two-step” methods, these policy functions then identify a set of structural parameters that are consistent with the dynamic model, the IV restrictions and the data. We provide computed illustrations to both single-agent and oligopoly examples. We also present a simple empirical analysis that, among other things, supports the counterfactual study of an environmental policy entailing an increase in sunk costs.