Research

Recent Submissions


Abstract: Instrumental variable models with repeated endogenous treatments are popular in empirical research using pooled cross-sectional or short panel datasets. This paper proposes a novel semi-parametric approach that explicitly considers treatment effect dynamics by allowing for 1) path-dependency in the contemporaneous treatment effect and 2) a direct carryover effect from last period's treatment. We show that if either of these new features is present and external instruments are serially correlated, the textbook two-stage least-squares estimator is invalid. We apply our proposed estimation and inference approach to revisit the work of Acemoglu et al. (2016). Using their industry-level data, we find that the contemporaneous impact of increased Chinese import competition on US manufacturing employment depends on the import exposure of the preceding period. In particular, the trade shock an industry received over 1991-1999 magnifies the negative impact of the trade shock over 1999-2011. The magnifying pattern is mild until the import exposure increase over 1991-1999 exceeds a certain threshold. 

 

Abstract: Regression discontinuity (RD) is a popular tool for the analysis of economic policies or treatment interventions. This research extends the classic static RD model to a dynamic framework, where observations are eligible for repeated RD experiments and, therefore, treatments. Such dynamics often complicate the identification and estimation of longer-term average treatment effects.  Previous empirical papers with such designs typically ignored the dynamics in the model or adopted restrictive identifying assumptions. This paper presents identification strategies under various sets of weaker identifying assumptions and proposes associated estimation and inference methods. The proposed methods are applied to revisit the effect of California local school bonds in the seminal study of Cellini et al. (2010). 


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Working Papers/Projects