1. Justice Modelling @ Griffith 1 Juvenile Offending Trajectories A Queensland Study

2. Justice Modelling @ Griffith 2 Presentation Background Current study Results Limitations and future research Conclusions

3. Justice Modelling @ Griffith 3 Criminal Careers Based on longitudinal cohort studies Exploring initiation, frequency, duration, specialisation, escalation and desistance Focus on identifying offender sub-populations

4. Justice Modelling @ Griffith 4 Criminal Careers E.g. Wolfgang et. al. (1975) –Chronics = >5 offences Farrington et. al. (1987) –‘Frequents’ and ‘Occasionals’ Moffitt et. al. (1993) –‘Life course persistent’ and ‘adolescent- limited’ offenders

5. Justice Modelling @ Griffith 5 Offending Trajectories

6. Justice Modelling @ Griffith 6 Offending Trajectories

7. Justice Modelling @ Griffith 7 Trajectory models Land and Nagin (1993) developed Semiparametric Group Based Method (SPGM) Group together ‘similar’ trajectories of offending Identify offender subgroups from the data rather than imposing ex ante definitions

8. Justice Modelling @ Griffith 8 Current study Develop a trajectory model of juvenile offending Explore correlates of trajectory membership Assess predictive validity of trajectories

9. Justice Modelling @ Griffith 9 Cohort People born in 1983 or 1984 with one or more finalised court appearances in Queensland Offending (cautioning and court) modelled between the ages of 10 and 16

10. Justice Modelling @ Griffith 10 Trajectory model

11. Justice Modelling @ Griffith 11 Late Onset Group Included more than two-thirds of the cohort Average of 2.3 offences as juveniles Responsible for 40% of the entire cohort’s offending

12. Justice Modelling @ Griffith 12 Adolescent Limited Group Included 20% of the cohort Committed 23% of the offences committed by the whole cohort Early onset with offending peaking at age 14.

13. Justice Modelling @ Griffith 13 Chronic group Included just over one-tenth of the cohort Responsible for 33% of the entire cohort’s offending Average of 10.5 juvenile offences each

14. Justice Modelling @ Griffith 14 Six factors explored: –Sex –Indigenous status –Remoteness of residence –Socio-economic disadvantage (of area of residence) –Child protection history –First court outcome Factors associated with trajectories

15. Justice Modelling @ Griffith 15 Factors associated with trajectories Multivariate analysis: –Little difference between adolescent-limited and adolescent-onset groups –Males more than twice as likely as females to follow ‘chronic’ trajectory –Indigenous offenders between 3 and 5 times as likely as non-Indigenous to follow ‘chronic’ trajectory

16. Justice Modelling @ Griffith 16 Factors associated with trajectories Multivariate analysis: –Young people with child protection substantiations were 2 – 4 times more likely to follow ‘chronic’ trajectory –Young people with a supervised order at the first court appearance were around 1.5 times more likely to follow ‘chronic’ trajectory

17. Justice Modelling @ Griffith 17 Predictive validity of trajectories Relationship between juvenile offending trajectory and adult offending For this study, adult offending was based on adult court appearances and was simply coded as a yes/no variable

18. Justice Modelling @ Griffith 18 Predictive validity of trajectories

19. Justice Modelling @ Griffith 19 Predictive validity of trajectories When sex, Indigenous status, remoteness and SED, child protection and first court outcome were controlled for in a logistic regression model: –Chronics were 2.7 times more likely to progress than late onset offenders –Chronics were 3.3 times more likely to progress than adolescent limited offenders

20. Justice Modelling @ Griffith 20 Findings Trajectory model similar to U.S., U.K. and New Zealand models Consistency of results adding evidence to a model of offending that includes two or more subpopulations of offenders

21. Justice Modelling @ Griffith 21 International comparisons

22. Justice Modelling @ Griffith 22 Findings Expected differences between males and females; Indigenous and non-Indigenous offenders Some evidence that some females do follow a chronic offending trajectory

23. Justice Modelling @ Griffith 23 Findings Child protection history strongly related to offending trajectory Offending trajectories strongly predict future offending at an aggregate levels Similarities between late-onset and adolescent-limited groups need further examination

24. Justice Modelling @ Griffith 24 Limitations of study Short time frame Limited range of factors available Sample attrition Use of official data for offending

25. Justice Modelling @ Griffith 25 Future research Extend study into adult offending Explore distinct trajectory models based on sex and Indigenous status Studies of how interventions/social changes (such as marriage, employment etc) affect trajectory group membership