A Micro-Simulation Model Of The Juvenile Justice System In Queensland

The operation of criminal justice systems (broadly the police, the courts and corrections) is a complex and expensive process. Management of these systems depends on some knowledge of the long-term and cross-system impacts of policy changes across the system. Simulation models are valuable tools in the administration of criminal justice systems, providing the ability to project the relative effects of changes to policies based on current system information. Presented in this paper is a summary of the development of the Queensland Juvenile Justice Simulation Model (QJJSM). QJJSM is a micro simulation model that simulates the progress of individual young offenders through their juvenile offending careers. Historically, simulation models of justice systems have often quickly fallen into disuse. This has primarily occurred due to the over-complexity of the models, resulting in models that are difficult to maintain and that the user base of justice policy makers have found difficult to use and understand. With this in mind, the development of the QJJSM focussed on producing a simple, clearly defined model with an intuitive user-interface. Furthermore, the model was designed to rely only on data that was already available from current administrative systems, ensuring that the maintenance of model parameters was not a difficult task. The QJJSM is a parsimonious model that simulates the initiation of new offenders, the commission of specific offences, the decision of the youth court, and reoffending behaviour In addition, three leverage points are included. These leverage points allow the user to add crime prevention, diversion and post-court intervention programs to the base system and explore their medium-term impacts. The model's schema is presented in Figure 1. [GRAPHICS] An example of the model's use is presented in the paper. The example simulates the implementation of an early-intervention crime prevention program in North and Far North Queensland. The program is aimed at all young people aged between five and ten and is successful at preventing 12% of prospective offenders. The results of this program over ten years are presented, highlighting the lag between the program's commencement and the effect flowing through to the juvenile justice system as well as the differential impact on Indigenous and non-Indigenous offenders due to the locations targeted. The example scenario also provides estimates of the financial impact of the program. The model presented is already in use in the Queensland juvenile justice system and it is expected that its success will enable the development of further justice system simulation models.