Categorizations of several important covariates, such as age (in years); family living structure (living with both parents or living with a single parent/others); household economic status (low, middle, and upper); academic performance (low, middle, and upper); perceived body weight (underweight, about right, and overweight); subjective sleep evaluation (satisfaction or dissatisfaction), and depressed mood ("yes" if they had felt so sad or hopeless almost every day for 2 weeks or more in a row that you stop doing some usual activities during the past 12 months) were conventionally defined and straightforward, as shown in Table 2.19 We also included current alcohol drinking ("yes" if they had consumed alcohol one or more days during the past 30 days), current cigarette smoking ("yes" if they had smoked at least one cigarette during the past 30 days), current butane gas or glue sniffing ("yes" if they often or sometimes sniffed butane gas or glue), and current unhealthy weight control behaviors ("yes" if they had participated in any of the following behaviors during the past 30 days: fasting for 12 hours or more; eating less;
