Table 2.

Covariate balancing of nearest-neighbor with caliper matching

Variable	Mean		Bias (%)	Bias reduction (%)	t	p-value
	Treated	Control
Age	63.05	62.93	1.30	92.60	0.59	0.55
Gender	0.53	0.54	−1.10	37.70	−0.52	0.60
Rural area	0.91	0.91	−1.10	98.30	−0.69	0.49
Education	0.23	0.22	1.20	96.80	0.61	0.54
Household economic level	−0.95	−0.95	0.00	99.90	−0.02	0.98
Marital status	0.83	0.83	−1.10	−187.80	−0.52	0.60
Retire status	0.05	0.05	−0.20	99.60	−0.10	0.92
Smokers	0.45	0.46	−1.60	77.90	−0.74	0.46
Drinkers	0.25	0.24	2.00	21.30	0.93	0.35
Sleep time	0.54	0.54	0.00	98.80	0.02	0.99
Social activity participation	0.46	0.47	−4.70	82.10	−1.71	0.09
BMI	23.40	23.49	−2.30	86.10	−1.05	0.29
Diabetes	0.06	0.06	−1.50	83.70	−0.73	0.47
Lung diseases	0.15	0.15	0.70	94.10	0.30	0.76
CVDs	0.42	0.43	−0.70	32.20	−0.31	0.76
Disability	0.14	0.14	0.20	98.00	0.09	0.93
Self-reported health	0.88	0.91	−3.80	78.80	1.04	0.30
Sample	Pseudo R2	LR chi2	p > chi2	Mean Bias	R	Var (%)
Unmatched	0.147	1899.82	0.00	20.00	0.38*	67
Matched	0.001	15.75	0.54	1.40	1.14	0

Notes: BMI, Body Mass Index; CVDs, cardiovascular diseases.