1) Demographic and socioeconomic variables
Information on demographic and socioeconomic characteristics (age, sex, school grade [middle school high school], residential type, perceived socioeconomic state [SES], and academic achievements) was evaluated. The type of residence was assessed as living with parents and without parents (such as living with relatives, living independently such as in a dormitory, or in an orphanage). The degree of SES and academic achievements were initially categorized as high, middle-high, middle, middle-low, and low. However, we categorized these as high (high or middle-high), middle (middle), or low (middle-low or low).