We develop a framework for difference-in-differences designs with staggered treatment adoption and heterogeneous causal effects. We show that conventional regression-based estimators fail to provide unbiased estimates of relevant estimands absent strong restrictions on treatment-effect...

When estimating the effects of treatments defined by complex formulas, researchers often use simple functions of exogenous shocks as instruments. A leading example is "simulated instruments" for public policy eligibility, which capture variation in state-level policy generosity. We show how more...

Recent work shows that popular partially-linear regression specifications can put negative weights on some treatment effects, potentially producing incorrectly-signed estimands. We counter by showing that negative weights are no problem in design-based specifications, in which low-dimensional...

A broad empirical literature uses “event study” research designs for treatment effect estimation, a setting in which all units in the panel receive treatment but at random times. We make four novel points about identification and estimation of causal effects in this setting and show their...

Motivated by a recent literature on the double-descent phenomenon in machine learning, we consider highly over-parameterized models in causal inference, including synthetic control with many control units. In such models, there may be so many free parameters that the model fits the training data...

We show that examiner-driven variation in patent rights leads to quantitatively large impacts on several patent outcomes, including patent value, citations, and litigation. Notably, Patent Assertion Entities (PAEs) overwhelmingly purchase patents granted by "lenient" examiners. These examiners...

Das Projekt analysiert die Preiswirkungen der Mehrwertsteuersenkung im Juli 2020 sowie die der entsprechenden Anhebung im Januar 2021 im Rahmen des Konjunkturpakets der Bundesregierung im Zuge der Corona-Pandemie. Die Untersuchung basiert auf Scannerdaten der GfK, die Informationen über die...