Table 2.

Granger causality tests of pairs between nighttime population, symptom onsets, confirmed case reports, and R_t.

Equation	Excluded	Chi-square (4)	P value
Rt a	Nighttime population	42.36	<.001
	Symptom onsets	18.12	.001
	Confirmed case reports	13.67	.008
Nighttime population	Rt	67.28	<.001
	Symptom onsets	26.45	<.001
	Confirmed case reports	62.51	<.001
Symptom onsets	Rt	9.42	.051
	Nighttime population	47.71	<.001
	Confirmed case reports	10.36	.04
Confirmed case reports	Rt	14.39	.006
	Nighttime population	12.93	.01
	Symptom onsets	82.23	<.001

^aR_t: effective reproduction number.