Table 7 Heterogeneity analysis of the association between Urban and Rural Resident Basic Medical Insurance and instrumental activity of daily living disability among the middle-aged and older adults in China

URRBMI

0.5690^*

0.5815^**

0.6392^*

0.5412^*

(0.1520)

(0.1205)

(0.1401)

(0.1415)

Age

1.1055^**

1.0535^**

1.0749^**

1.0437^**

(0.0312)

(0.0121)

(0.0092)

(0.0116)

Gender

0.6157^*

0.5220^**

0.5616^**

0.5184^**

(0.1172)

(0.0878)

(0.0904)

(0.0949)

Marital status

1.1689

1.2838

1.4294

1.1440

(0.5090)

(0.2324)

(0.2954)

(0.3069)

Residency area

1.2297

0.7399

(0.3084)

(0.1433)

Education status

0.5812^*

0.6549^*

0.6843^*

0.5024^*

(0.1544)

(0.1207)

(0.1272)

(0.1689)

Household income

0.9439^**

0.9201^**

0.9208^**

0.9491^*

(0.0206)

(0.0257)

(0.0233)

(0.0247)

PM_2.5 concentrations

0.9789^*

1.0101

0.9993

0.9985

(0.0090)

(0.0071)

(0.0086)

(0.0110)

Having tap water

0.3490^**

0.5916^**

0.4494^**

0.5205^*

(0.0964)

(0.1156)

(0.1038)

(0.1710)

Constant

0.0139^**

0.0654^**

0.0228^**

0.1683

(0.0224)

(0.0619)

(0.0188)

(0.1686)

Number of observations

890

1034

1187

737

Wald chi-squared

61.40^**

81.06^**

139.32^**

85.19^**

Pseudo R-squared

0.0970

0.0817

0.1183

0.0880