Table 4.

Balance test results.

Variable	Sample	Mean		Standardization deviation		T statistic
		Control group	Treatment group	Standardization deviation	Bias%
Education level	Before matching	8.648	9.079	14.0	96.9	2.63
	After matching	8.958	9.079	−0.4		−0.16
Age	Before matching	42.28	42.168	−1.1	−400.5	−0.20
	After matching	41.59	42.168	5.4		1.97
Healthy	Before matching	3.812	3.838	3.0	−51.4	0.59
	After matching	3.878	3.838	−4.5		−1.66
Monthly income logarithm	Before matching	7.488	7.752	29.7	93.8	6.02
	After matching	7.736	7.752	1.8		0.70
Toilet type	Before matching	2.062	1.493	−46.3	96.1	−10.15
	After matching	1.471	1.493	1.8		0.77
Economic satisfaction	Before matching	3.201	3.207	0.5	−32.9	0.10
	After matching	3.200	3.207	0.7		0.25
Air pollution degree	Before matching	3.181	2.920	−30.7	97.8	−5.93
	After matching	2.926	2.920	−0.7		−0.24
Household consumption expenditure	Before matching	10.4	10.586	23.9	74.8	4.46
	After matching	10.539	10.586	6.0		2.17
Nation	Before matching	0.905	0.962	23.3	73.6	5.42
	After matching	0.947	0.962	6.1		2.65
Married	Before matching	0.949	0.910	−15.4	49.9	−2.79
	After matching	0.890	0.910	7.7		2.39
Divorce or widowhood	Before matching	0.015	0.019	2.9	−76.9	0.56
	After matching	0.013	0.019	5.2		1.98
Gender	Before matching	0.613	0.571	−8.4	91.8	−1.65
	After matching	0.575	0.571	−0.7		−0.25
Professional types	Before matching	1.752	1.565	−20.5	71.6	−4.13
	After matching	1.617	1.565	−5.8		−2.17
Family size	Before matching	4.527	4.410	−6.6	−17.3	−1.26
	After matching	4.274	4.410	7.7		2.82
Year	Before matching	2017.1	2017	−5.3	9.0	−1.05
	After matching	2017	2017	4.9		1.76
Province	Before matching	2.000	1.600	16.6	77.9	3.16
	After matching	2.000	2.100	−3.7		−1.29