CJB203
The NSW Prison Population Simulation Model: A policy analysis tool
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Summary
Aim
To describe a simulation model of the NSW prison system and demonstrate its utility as a tool for examining the effects of changes to the criminal justice system that influence the number of prisoners in custody.
Method
The model consists of four states (bail, remand, custody and parole) and a set of parameters governing flows into and out of those states as well as lengths of stay in each state. Data for the model were sourced from police, court and correctional databases.
Results
The prison system is extremely sensitive to changes in the percentage of persons refused bail. A one percentage point change in the percentage of persons refused bail by a court increases the remand population by 7.66 per cent, the sentenced prisoner population by 6.03 per cent and the parole population by 6.15 per cent.
Conclusion
It is feasible to build a simple model of the prison system which is easy to maintain but nonetheless useful in analysing the likely consequences of changes in arrest, bail and sentencing policy.
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