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BB105

Author Neil Donnelly, Imogen Halstead, Simon Corben and Don Weatherburn
Published April 2015
Report Type Bureau Brief No. 105
Subject Prisons and prisoners; Socioeconomic factors and crime; Statistical methods and modelling
Keywords prison population, ARIMA, forecast, demography, population

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Summary

Aim

To provide short and long term forecasts of growth in the NSW prison population.

Method

ARIMA modelling was used to generate the short-term forecast. The long-term forecasts are based on forecast changes in the population and population age structure, coupled with information about long-term changes in age-specific rates of imprisonment.

Results

The short-term forecast is that, if relevant influences remain unchanged, NSW will have 12,191 prisoners by March 2017. If age-specific rates of imprisonment remain constant, we expect the NSW prison population to rise to 12,500 by June 2036. If age-specific rates of imprisonment rise in a manner commensurate with trends observed over the past decade, the prison population should reach 15,600 by June 2036. If age-specific imprisonment rates rise according to the trends observed since 1982, the prison population should reach 17,600 by June 2036.

Conclusion

The NSW prison population is likely to rise over both the short and long-term unless measures are taken to reduce the demand for prison accommodation.

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