Difference in differences methods have become very popular in applied work. This paper provides a new method for inference in these models when there are a small number of policy changes. This situation occurs in many implementations of these estimators. Identification of the key parameter...

We consider a linear panel event-study design in which unobserved confounds may be related both to the outcome and to the policy variable of interest. We provide sufficient conditions to identify the causal effect of the policy by exploiting covariates related to the policy only through the...

One of the best known results in modern public finance is the Chamley-Judd result showing that the optimal tax rate on capital income is zero in the long-run. In this paper, we reexamine this result by analyzing a series of generalizations of the Chamley-Judd formulation. We show that in a model...

We examine the retail prices and wholesale prices of a large supermarket chain in Chicago over seven and one-half years. We show that prices tend to fall during the seasonal demand peak for a product and that changes in retail margins account for most of those price changes; thus we add to the...

We measure the causal effects of income and wealth on the demand for private-label products. Prior research suggests that these effects are large and, in particular, that private-label demand rises during recessions. Our empirical analysis is based on a comprehensive household-level transactions...

We analyze the initial conditions bias in the estimation of brand choice models with structural state dependence. Using a combination of Monte Carlo simulations and empirical case studies of shopping panels, we show that popular, simple solutions that mis-specify the initial conditions are...

Participation in non-traditional work arrangements has increased dramatically over the last decade, including in settings where new technologies lower the transaction costs of providing labor flexibly. One prominent example of flexible work is the ride-sharing company Uber, which allows drivers...

For many consumer packaged goods products, researchers have documented a form of state dependence whereby consumers become "loyal" to products they have consumed in the past. That is, consumers behave as though there is a utility premium from continuing to purchase the same product as they have...