CHANGES TO OFFENCE DATA
The Australian Standard Offence Classification (ASOC) provides a basis for the standardised collection, analysis and dissemination of offence data within crime and justice statistics. The Prisoner Census collection between 2001 and 2008 was primarily based on the 1997 edition of ASOC (ASOC97). Prior to this period offences were classified to the Australian National Classification of Offences (ANCO).
From the 2009 reference period, offence data from the Prisoner Census collection will primarily be based on the revised edition of ASOC (ASOC08). Six jurisdictions (New South Wales, Victoria, South Australia, Tasmania, Northern Territory and the Australian Capital Territory) have migrated to the revised offence classification in 2009. Offence data for these jurisdictions presented in this issue are based on ASOC08. Data for Queensland and Western Australia are based on ASOC97. It is expected that these two jurisdictions will migrate progressively to the revised classification within the next two years.
The revised classification only impacts the Prisoner Census time series in relation to offence information. Prisoner numbers are not impacted. The number of offence divisions have remained the same, however changes have been made to offence subdivisions and groups resulting in some subdivisions and groups moving across divisions. Additionally, as part of the migration, some jurisdictions discovered incorrect assignment of local offence codes to ASOC, resulting in further changes to 2009 offence data.
The impacts of the migration have been measured based on four jurisdictions. The largest impacts occurred in divisions 05, 11, 13 and 16 with movements greater than 15%. However, the size of these movements was largely a reflection of the small numbers within these offence categories. All other divisions were not greatly impacted.
Caution should be exercised when making comparisons to offence data prior to 2009 for those jurisdictions who have migrated to ASOC08, or comparing 2009 data between migrated and non-migrated jurisdictions. For more details about these impacts, refer to the Technical Note.