*2.2. Measures*

#### 2.2.1. Objective Social Class

Three indicators of the objective social class (i.e., educational attainment, occupation, and monthly income) were measured. First, participants reported their education level by choosing one of the following six options: 1 = "primary school or below", 2 = "junior high school", 3 = "High school diploma or equivalent", 4 = "junior college", 5 = "bachelor's degree", or 6 = "postgraduate degree or higher". Second, they reported their occupations in one of six categories, according to the classification criteria offered by previous Chinese research [38]: 1 = "student" (excluded); 2 = "temporary workers, unemployed people, unskilled workers, and agricultural workers, such as farmers"; 3 = "manual laborers, selfemployed workers, skilled workers, and workers at the same level, such as industrial workers and service employees"; 4 = "general management personnel, general professional and technical personnel, and clerical staff, such as salespersons and drivers"; 5 = "middle management, middle-level professional and technical personnel, and assistant professional personnel, such as doctors, teachers, and engineers"; and 6 = "professional senior managers, senior professional and technical personnel, and professional supervisors, such as civil servants, company managers, and project managers." Third, monthly income was divided into seven categories: <1000 RMB, 1000–2000 RMB, 2000–4000 RMB, 4000–8000 RMB, 8000–16,000 RMB, 16,000–32,000 RMB, and 32,000 RMB or more, with an overall value ranging from 1 to 7. Following the methods of previous studies [39,40], the three scores were then standardized, and an exploratory factor analysis extracted one principal component for the three items. The factor loading for each item was multiplied by the respective item score, and these scores were summed. Eigenvalues were then used to divide this sum and create the final objective class score. Higher scores represented a higher objective class.
