This article reviews the empirical evidence on firm heterogeneity in international trade. A first
wave of empirical findings from microdata on plants and firms proposed challenges for …

In this article, we present ppmlhdfe, a new command for estimation of (pseudo-) Poisson
regression models with multiple high-dimensional fixed effects (HDFE). Estimation is …

There is growing evidence that firm-specific pay premiums are an important source of wage
inequality. These premiums will contribute to the gender wage gap if women are less likely …

We study the role of establishment-specific wage premiums in generating recent increases
in West German wage inequality. Models with additive fixed effects for workers and …

We study the drivers of geographic variation in US health care utilization, using an empirical
strategy that exploits migration of Medicare patients to separate the role of demand and …

We propose leave‐out estimators of quadratic forms designed for the study of linear models
with unrestricted heteroscedasticity. Applications include analysis of variance and tests of …

Controlling for unobserved heterogeneity (or “common errors”), such as industry-specific
shocks, is a fundamental challenge in empirical research. This paper discusses the …

Research in international trade has changed dramatically over the last twenty years, as
attention has shifted from countries and industries towards the firms actually engaged in …

Maintaining singleton groups in linear regressions where fixed effects are nested within
clusters can overstate statistical significance and lead to incorrect inference. Due to this …

We propose a framework to identify and estimate earnings distributions and worker
composition on matched panel data, allowing for two‐sided worker‐firm unobserved …