Table 3.

Event study regressions of self-reported face mask use, SARS-CoV-2 reproduction numbers, and growth rates of COVID-19 cases on face mask recommendations. The table reports percentage point changes in self-reported face mask use and growth rates of COVID-19 cases as well as unit changes in reproduction numbers. Data sources: COVID-19 Trends and Impact Survey, Oxford COVID-19 Government Response Tracker, Our World in Data—COVID-19 data set, and Google COVID-19 Community Mobility Reports.

	Self-reported face mask usea,b (observations=13,159)			Reproduction numbera,b (observations=8500)			Case growth in casesa.b (observations=8325)
	Percentage points (SE)	P value	Units (SE)		P value	Percentage points (SE)		P value
ATTc	5.84 (1.60)	<.001	−0.06 (0.16)		.70	−2.45 (4.54)		.59
Mask mandate	11.70 (3.44)	.001	−0.19 (0.09)		.04	−2.01 (1.36)		.15
Subgroup mandate	13.60 (4.34)	.002	−0.18 (0.12)		.16	−3.18 (2.22)		.16
Level 2—mandate	1.16 (3.20)	.72	0.05 (0.08)		.54	2.22 (1.38)		.11
Level 3—mandate	−1.27 (3.88)	.74	−0.08 (0.10)		.42	0.76 (1.99)		.70
School closure	—d	—	0.07 (0.05)		.12	1.13 (0.92)		.22
Ban on events	—	—	−0.12 (0.05)		.02	−0.38 (0.77)		.62
Ban on gatherings	—	—	−0.02 (0.05)		.70	−0.70 (1.02)		.50
Curfew	—	—	−0.09 (0.04)		.02	−0.81 (0.66)		.23
International travel restrictions	—	—	−0.09 (0.06)		.15	−1.58 (1.41)		.27
Protection of older adults	—	—	0.04 (0.05)		.42	−0.78 (1.50)		.61
Mobility	—	—	−0.01 (0.01)		.26	0.37 (0.098)		<.001
Tests per 100,000 inhabitants	—	—	0 (0)		.20	0 (0)		.02

^aAll models have been estimated with country and time fixed effects.

^bSE (in parentheses) are clustered at the country level.

^cATT: Average Treatment Effect on the Treated. The ATT is obtained by averaging Sun and Abraham [26] interaction-weighted estimates of postmandate period effects.

^dThe model was specified with ATT and subgroup as well as level-2 and level-3 mandate effects, only.