Panel or grouped data are often used to allow for unobserved individual heterogeneity in econometric models via fixed effects. In this paper, we discuss identification of a panel data model in which the unobserved heterogeneity both enters additively and interacts with treatment variables. We...

We study the impact of the Panama Canal on the development of Canada's manufacturing sector in the years from 1900 to 1939. Using newly digitized county-level data from the Census of Manufactures and a market-access approach, we exploit the plausibly exogenous nature of this historical episode...