Before revision:  In regressions studying the effect of randomly generated placebo sectoral shocks on actual labor market outcomes in U.S. commuting zones, we find that a 5 \% level significance test based on standard errors clustered at the state level rejects the null of no effect in up to 45 \% of the placebo interventions.
After revision:  In regressions studying the effect of randomly generated placebo sectoral shocks on actual labor market outcomes in U.S. Commuting Zones. Tests based on commonly used standard errors with 5 \% level significance test based on standard errors clustered at the state level rejects the null of no effect in up to 45 \% of the placebo interventions.