Table 2 Summary statistics of covariate variables

Sample size

11,592

100%

6320

100%

SHI

 Yes

11,274

97.26%

6185

97.86%

 No^a

318

2.74%

135

2.14%

Age

61.45

0.09

63.13

0.12

Gender

 Male

4938

42.60%

2931

46.38%

 Female^a

6654

57.40%

3389

53.62%

Education level

 Illiterate^a

3345

28.86%

1817

28.75%

 Primary school

4944

42.65%

2693

42.61%

 Middle school

2133

18.40%

1168

18.48%

 High school and above

1170

10.09%

642

10.16%

Marital status

 With a spouse^a

9842

84.90%

5306

83.96%

 Without a spouse

1750

15.10%

1014

16.04%

Living with children

 Yes

7052

60.84%

3522

55.73%

 No^a

4540

39.16%

2798

44.27%

Job

 Without a job^a

4137

35.69%

2926

46.30%

 Agricultural job

6341

54.70%

2890

45.73%

 Non-agricultural job

1194

9.61%

542

7.97%

Income

10086.14

186.82

10046.36

209.06

Ln income

8.65

0.01

8.66

0.01

Childhood health

2.83

0.01

2.76

0.01

SRH

3.65

0.01

3.74

0.01

Chronic diseases

 Yes

6814

58.78%

3891

61.57%

 No^a

4778

41.22%

2429

38.43%

ADL disability

 Yes

2601

22.44%

1866

29.53%

 No^a

8991

77.56%

4454

70.47%

PHI

 Yes

206

1.78%

104

1.65%

 No^a

11,386

98.22%

6216

98.35%

Travel time

25.40

0.18

26.79

0.23

Urban or rural

 Urban

4036

34.82%

2348

37.15%

 Rural^a

7556

65.18%

3972

62.85%

City GRP

36352.24

205.43

36618.77

268.82

ln city GRP

10.35

0.01

10.36

0.01

Region

 East China^a

3671

31.67%

1992

31.52%

 Central China

3294

28.42%

1793

28.37%

 West China

4627

39.92%

2535

40.11%