The frequency and seriousness of delinquent behaviour were investigated orally and filled out by a researcher using the Dutch version  of the Self-report Delinquency Scale (SRD) . This questionnaire has 29 items (including two items of violation: fare dodging and lighting fireworks when prohibited) and the internal consistency of the total score is excellent with Cronbach’s α = 0.85 [79, 81]. The questionnaire explored the frequency of offences committed both during the respondent’s lifetime and in the previous 6 months. In addition, the items were also divided into four different offence categories: destruction/public order offences (5 items, Cronbach’s α = 0.64), property offences (11 items, Cronbach’s α = 0.79), aggression/violent offences (8 items, Cronbach’s α = 0.7) and drug offences (3 items, Cronbach’s α = 0.72) . The frequencies per offence category were recoded into dichotomous variables (Yes/No), due to the skewed distribution of the data. Lifetime and previous 6 months’ prevalence are presented in Table 1. Mean scores based on the frequencies of offences in the previous 6 months were used as outcome measure (see Table 5). The 27 items (excluding two items of violation) add up to one total delinquency score reflecting the multiplication of the seriousness of the offences and their frequency. The seriousness is divided into minor and serious offences based on applicable legal penalties; minor offences have a maximum custodial sentence of 48 months (score 1) and serious offences have a minimum custodial sentence of 48 months (score 2) [79, 80].