We exploit tax-induced exogenous variance in the price of union membership to identify the effects of changes in firm union density on firm productivity and wages in the population of Norwegian firms over the period 2001 to 2012. Increases in union density lead to substantial increases in firm...

A detailed longitudinal dataset is assembled containing annual performance and biographical data for every player over the entire history of professional major league baseball. The data are then aggregated to the team level for the period 1920-2009 in order to test whether teams built on a more...