Table 3 The VIF value of all independent variables

Gender

1.131

Age groups

1.219

Marital status

1.205

Living separate and apart

1.037

Shenzhen Hukou

1.224

Length of residency

1.123

Education level

1.075

Monthly income (RMB)

1.250

Health insurance

1.156

Sexual orientation

1.004

Ever CT tested

1.293

Ever CT diagnosed

1.210

Current STI-related symptoms

1.033

Knowledge Q1

1.508

Knowledge Q2

1.497