Table 1.

Variable definitions

Variable	Variable definitions
Wave
1991	Reference group
1993	1 if survey conducted at 1993; 0 otherwise
1997	1 if survey conducted at 1997; 0 otherwise
2000	1 if survey conducted at 2000; 0 otherwise
2004	1 if survey conducted at 2004; 0 otherwise
2006	1 if survey conducted at 2006; 0 otherwise
2009	1 if survey conducted at 2009; 0 otherwise
2011	1 if survey conducted at 2011; 0 otherwise
Region group
Urban	Reference group
Suburban	1 if respondents lived in suburban; 0 otherwise
Town	1 if respondents lived in town; 0 otherwise
Rich village	1 if respondents lived in rich village; 0 otherwise
Poor village	1 if respondents lived in poor village; 0 otherwise
Income group
Quintile1	Reference group
Quintile2	1 if in the second highest quintile; 0 otherwise
Quintile3	1 if income in the middle quintile; 0 otherwise
Quintile4	1 if income in the second lowest quintile; 0 otherwise
Quintile5	1 if income in the bottom quintile; 0 otherwise
Age group
0~	Reference group
16~	1 if aged 16–30; 0 otherwise
31~	1 if aged 31–45; 0 otherwise
46~	1 if aged 46–60; 0 otherwise
61~	1 if older than 60; 0 otherwise
Gender
Male	Reference group
Female	1 if female; 0 otherwise
Marriage status
Never married	Reference group
Married	1 if married; 0 otherwise
Others	1 if divorced, widowed, separated, or unknow; 0 otherwise
Education level
Below primary school	Reference group
Grad from primary	1 if grad from primary; 0 otherwise
Junior middle school	1 if grad from junior middle school; 0 otherwise
Senior middle school or above	1 if grad from senior middle school or above; 0 otherwise
Health insurance
Yes	Reference group
No	1 if no insurance; 0 otherwise
BMI
Underweight	Reference group
Normal weight	1 if 18.5 < = BMI < 26; 0 otherwise
Overweight	1 if 26 < = BMI < 31; 0 otherwise
Obese	1 if BMI > = 31; 0 otherwise