Table 4 Assignment of logistic regression analysis variables

Dependent variable

 Mental health

1 = good, 2 = moderately, 3 = poor, 4 = bad

Independent variables

 Sex

0 = male, 1 = female

 Age (year)

1 = 65–69, 2 = 70–74, 3 = 75–79, 3 = ~ 80

 Education level

1 = high school and above, 2 = junior middle school, 3 = primary school, 4 = illiteracy

 Marital status

0 = single (never married, divorced, widowed), 1 = married

 Living arrangement

0 = living alone, 1 = not living alone

 Annual per capital income

1 = ~ 1000, 2 = ~ 2000, 3 = ~ 3000, 4 = ~ 4000, 5 = ~ 5000

 Chronic disease

0 = yes, 1 = no

 Race

0 = Han population, 1 = minority

 Self-rated health

1 = very good, 2 = fairly good, 3 = moderately, 4 = fairly bad, 5 = very bad