Table 4 Robustness tests based on the cluster analysis with 5 and 7 clusters

Socioeconomic status

 Household income

0.0078

3.09

0.0080

3.17

 Physical labor

0.0025

1.00

0.0022

0.86

 Pension

0.0037

1.47

0.0037

1.46

 Education duration

0.0116

4.61

0.0118

4.66

Residence location

 Household registration

0.0081

3.20

0.0082

3.25

 Region

0.0018

0.69

0.0017

0.68

Healthcare accessibility

 Medical insurance

0.0032

1.25

0.0031

1.23

 Reimbursement rate

0.2093

83.04

0.2078

81.79

 Distance to health facilities

0.0021

0.83

0.0021

0.82

Unobserved

0.0021

0.81

0.0053

2.09

Total

0.2520

100.00

0.2541

100.00