Table 1.

Randomization balance test.

	(1)	(2)	(3)	(4)
	All	Control	Treatment	C-T difference
Intent-to-drop-out (pre-COVID-19)	0.137	0.137	0.136	$-$0.001
	[0.343]	[0.344]	[0.343]	(0.003)
Female	0.611	0.611	0.611	0.001
	[0.487]	[0.488]	[0.487]	(0.004)
Parent is a doctor	0.102	0.103	0.102	$-$0.001
	[0.303]	[0.304]	[0.302]	(0.002)
Family location, vs. rural areas
Urban	0.287	0.287	0.288	0.002
	[0.453]	[0.452]	[0.453]	(0.003)
Suburban	0.411	0.412	0.410	$-$0.002
	[0.492]	[0.492]	[0.492]	(0.003)
Pre-clinical period	0.581	0.582	0.580	$-$0.005
	[0.493]	[0.493]	[0.494]	(0.006)
Enrolled program, vs. 5-year program
Rural 5-year program	0.089	0.090	0.089	$-$0.004
	[0.285]	[0.286]	[0.284]	(0.002)
5+3-year program	0.066	0.066	0.066	0.001
	[0.249]	[0.249]	[0.249]	(0.003)
8-year program	0.016	0.016	0.017	0.000
	[0.127]	[0.126]	[0.128]	(0.001)
GPA, vs. ranked top 25%
25–50%	0.359	0.359	0.358	$-$0.001
	[0.480]	[0.480]	[0.479]	(0.003)
50–75%	0.212	0.213	0.210	$-$0.003
	[0.409]	[0.410]	[0.408]	(0.003)
Bottom 25%	0.063	0.063	0.064	0.001
	[0.244]	[0.243]	[0.244]	(0.002)
Undermatched in college admissions	0.378	0.378	0.377	$-$0.001
	[0.485]	[0.485]	[0.485]	(0.003)
Home access to internet	0.630	0.630	0.629	$-$0.001
	[0.483]	[0.483]	[0.483]	(0.003)
Having paid attention to COVID-19	0.635	0.635	0.634	0.000
	[0.482]	[0.481]	[0.482]	(0.003)
Teachers/Schoolmants at the frontline	0.646	0.642	0.651	0.008**
	[0.478]	[0.479]	[0.477]	(0.003)
Students	98,668	49,115	49,553
Schools	90	90	90

Notes: Column 1 shows the mean and standard deviation for each variable in the full sample. Columns 2 and 3 show the same statistics for the control and treatment groups, respectively. Column 4 reports the estimated treatment-control difference for each variable using eq. 4 without controlling for covariates ($y_{ij}=\alpha +\gamma Nudg{e}_{ij}+{ϵ}_{ij}$). A joint F test, performed by regressing the treatment indicator on all the covariates in this table, yields a statistic of 0.868 with a $p$-value of 0.607, suggesting that the treatment group assignment was not based upon any observed student attributes. Undermatched in college admissions is a self-reported indicator evaluating whether a student perceived his or her college entrance exam score to be above the others with the same admission outcome in the same cohort. Having paid attention to COVID-19 is a self-reported indicator for voluntary attention to COVID-19 related information. Teachers/Schoolmates at the frontline indicates whether students have teachers or schoolmates in their close social network who have served at the frontline in Wuhan, the epicenter of the epidemic in China. Robust standard errors are clustered at the college-grade level. *** $p<0.01$, ** $p<0.05$, * $p<0.1$.