Linear Estimation of Structural and Causal Effects for Nonseparable Panel Data

2026-07-30

AI Summary

This study addresses the challenge of identifying causal effects in nonseparable models when unobserved time-varying individual heterogeneity is correlated with explanatory variables. The authors propose a novel approach that approximates the conditional average potential outcomes using linear sieve methods, combined with individual-specific ridge regression and bias correction. Within a large-T asymptotic framework, this method achieves point identification, circumventing the partial identification issues common in traditional approaches. The resulting estimator admits an empirical Bayes interpretation, accommodates discrete treatment variables, and provides a unified framework for estimating average causal effects, counterfactual consumer welfare measures, and individual tax elasticities. An empirical application to supermarket scanner data demonstrates the method’s effectiveness by precisely quantifying the average equivalent variation and deadweight loss induced by price increases.

Abstract

This paper develops linear estimators for structural and causal parameters of nonseparable models using panel data. These models incorporate unobserved, time-varying, individual heterogeneity, which may be correlated with the regressors. Estimation is based on an approximation of a conditional average potential outcome by a linear sieve specification with individual-specific parameters. Effects of interest are estimated by a bias corrected average of individual ridge regressions. We demonstrate how this approach can be applied to estimate causal effects, counterfactual consumer welfare, and averages of individual taxable income elasticities. We show that the proposed estimator has an empirical Bayes interpretation and possesses a number of other useful properties. We formulate Large-$T$ asymptotics that can accommodate discrete regressors and which bypass partial identification in this case. We employ the methods to estimate average equivalent variation and deadweight loss for potential price increases using data on grocery purchases.

Problem

• nonseparable models
• panel data
• causal effects
• individual heterogeneity
• structural estimation

Innovation

• nonseparable panel data
• linear sieve estimation
• bias-corrected ridge regression
• empirical Bayes
• Large-T asymptotics