His primary research interests are econometrics, inequality, social mobility, economic growth, and macroeconomics. His work has documented the existence of status traps in intergenerational mobility, which can reduce the impact of favorable shocks or interventions for disadvantaged children and so hinder upward mobility. Recently, he also developed estimation and inference for a structural threshold regression model, which is particularly useful for the estimation of multiple equilibria and poverty traps. In general, his work focuses on issues of model uncertainly, parameter heterogeneity, nonlinearities, and mixed frequencies. His findings highlight the difficulty in evaluating causal claims when theory provides insufficient guidance for econometric specification, as is typically the case in empirical economic growth.