Staggered Treatment Effects With Selection on Unobservables: The Case of Endogenous Preferential Trade Agreement Effects on Trade

ABSTRACT This article combines insights from three strands of work: the one on self‐selection into treatments, the one on staggered treatment effects, and the one on preferential trade agreements (PTAs). We illustrate in a staggered treatment effects approach with selection on unobservables that in the phase since 1997, when exogenous staggered PTA effects had been found of insignificant importance, endogenous staggered PTAs exert positive effects that are statistically significant.