Limitations of the data

3.72     While the ABS PIA plays a pivotal role in providing vital imprisonment statistics for Australia, the series is not without limitations. As a census based collection, the statistics are based only on those prisoners who were present on the night of 30 June of the reference year. These statistics therefore only measure the ‘stock’ of persons in prison. They do not count or report on the total ‘flow’ of prisoners who come into and leave prison over a defined period.  Any person who may have entered and exited prison prior to June 30 is not included in the PIA statistics.

3.73     ‘Stock’ statistics are an important indicator of incarceration levels; however, they under count the number of prisoners who serve short sentences and, conversely, over count prisoners who serve longer sentences (being those who commit more serious offences and receive longer terms of imprisonment).

3.74     The statistics presented in the ABS PIA series are also incomplete:

  • The series does not report on fine defaulters in the prison system nor does it provide any information on whether persons in prison for traffic/driving licence offences are related to the operation of fines enforcement systems in some jurisdictions, i.e. where driver’s licences may be suspended as a result of non-payment of fines.

  • The PIA series is also unable to report on the number of remandees who go on to serve a term of imprisonment. In a recent report entitled What’s Causing the Growth in Indigenous Imprisonment in NSW? (2016), BOCSAR noted that up to 40 percent of Aboriginal and Torres Strait Islander defendants held on remand did not receive a custodial penalty on conviction in the study period. This statistic cannot be derived from ABS statistics and the extent to which remandees go on to serve prison sentences is not known.

  • PIA also does not report on indeterminate prisoners.[36]

Prison reception statistics

3.75     Unfortunately, publications that report on other aspects of the prison population (such as the number of people coming into or exiting prison) are not routinely reported or do not report in sufficient detail to monitor Aboriginal and Torres Strait Islander incarceration levels.