Table 5.

Covid-19 cases and school opening. Heterogeneity linked to population.

	(1)	(2)	(3)	(4)
	Covid-19 cases$\le$19 yo.	Covid-19 cases$>19$ yo.	Covid-19 cases pop density$\le$mean	Covid-19 cases pop density$>$mean
School opening (2nd lag)	0.005***	0.023***	0.031***	0.001
	(0.000)	(0.001)	(0.002)	(0.003)
Covid-19 (ln, 2nd lag)	−1.011***	−0.799***	−0.765***	−0.820***
	(0.010)	(0.008)	(0.007)	(0.007)
Covid-19 (ln, 3d lag)	−0.036***	−0.010**	−0.010**	−0.012***
	(0.006)	(0.005)	(0.004)	(0.004)
Covid-19 (ln, 4th lag)	−0.046***	−0.016***	−0.022***	−0.020***
	(0.006)	(0.005)	(0.004)	(0.005)
Covid-19 (change ln lag)	−1.000***	−0.871***	−0.846***	−0.890***
	(0.006)	(0.006)	(0.005)	(0.005)
Time dummies	Y	Y	Y	Y
Census area FE	Y	Y	Y	Y
Observations	530,944	530,944	319,296	211,648
R${}^2$ within	0.50	0.44	0.42	0.45
Number of Census areas	33,184	33,184	19,956	13,228

All regressions are weighted by propensity scores. ***, **, and * denote significance at 1%, 5%, and 10%, respectively. Standard errors are clustered at census area level. The dependent variables of column 1 and 2 are the natural log of Covid-19 cases in the population above and below 19 years old, respectively. The dependent variable of column 3 and 4 is the natural log of Covid-19 cases in all the population.