We provide a complete asymptotic distribution theory for clustered data with a large number of groups, generalizing the classic laws of large numbers, uniform laws, central limit theory, and clustered covariance matrix estimation. Our theory allows for clustered observations with heterogeneous...

Individuals may respond differently to their own past performance than to their teammates' performance in a multi-battle competition. Using field data from professional squash team tournaments, we show that while previous individual success begets more success, teammates' past performance has...

An increasingly popular trend in online businesses is the adoption of the freemium model, in which premium features are provided along with free features. By providing free features to a large fraction of users and by managing the social interactions between users and their friends, online...

In the presence of an endogenous treatment and a valid instrument, causal effects are (nonparametrically) point identified only for the subpopulation of compliers, given that the treatment is monotone in the instrument. Further populations of likely policy interest have been widely ignored in...

This paper discusses the solution of nonlinear integral equations with noisy integral kernels as they appear in nonparametric instrumental regression. We propose a regularized Newton-type iteration and establish convergence and convergence rate results. A particular emphasis is on instrumental...

The Instrumental Variable (IV) formula has become widely used to address the issue of identification of a causal effect in linear systems with an unobserved variable that acts as direct confounder. We here propose two alternative formulations to achieve identification when the assumptions...

In the canonical regression discontinuity (RD) design for applicants who face an award or admissions cutoff, causal effects are nonparametrically identified for those near the cutoff. The impact of treatment on inframarginal applicants is also of interest, but identification of such effects...

In this paper we establish a full information maximum likelihood approach to estimating the sample selection model with endogenous covariates. We also provide a test for exogeneity which indicates whether endogeneity is in fact a matter or not. In contrast to other methods proposed in the...

This paper sheds additional light on the relationship between firm level innovative capacity and export intensity. By drawing from the recent literature on exporters' heterogeneity, we apply quantile regression techniques to a sample of Italian firms in order to verify whether the effect of...