Socioeconomic status
SECONDARY
Children’s socioeconomic status (SES) was operationalized by their parents’ highest educational attainment which was assessed on a scale of 1–7 (no degree [1], secondary school degree (lower track) [2], secondary school degree (middle track) [3], high school diploma [4], apprenticeship [5], technical college [6], university degree [7]) which they had self-reported. Subsequently, a dichotomous scale was derived, which categorized the participants into two groups: those without a vocational qualification [1] and those with a vocational qualification [2].