National Offence Index

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A ranking tool for offences according to perceived seriousness of the crime

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About this publication

The National Offence Index (NOI) has been developed by the Australian Bureau of Statistics as a statistical tool to enable the output of nationally comparable offence information within the field of crime and justice statistics. The Index detailed in this publication supersedes the second version of the NOI released in 2009.

The National Offence Index is a tool which provides an ordinal ranking of the offence categories in the Australian and New Zealand Standard Offence Classification (ANZSOC) (cat. no. 1234.0) according to perceived seriousness in order to determine a principal offence. The purpose of the NOI is to enable the representation of an offender by a single offence in instances where multiple offences occur within the same incident or where defendants have multiple charges in criminal cases. For instance, where an offender has two or more offences within the same incident that could be classified to different offence categories of the ANZSOC classification (e.g. 0211 - Serious assault resulting in injury and 0621 - Blackmail and extortion), by applying the NOI, a 'principal offence' can be selected to represent that offender. In this instance 'Serious assault resulting in injury' is ranked higher on the NOI (25 vs 45), and as such would be selected as the principal offence.

The NOI has been revised to assign rankings to offence categories that were previously unranked. This change will bring greater clarity and comparability around the determination of a principal offence.


For further information about these and related statistics, contact the National Information and Referral Service on 1300 135 070, or email The ABS Privacy Policy outlines how the ABS will handle any personal information that you provide to us.

Historical development of the National Offence Index

The National Offence Index (NOI) was based on the Offence Seriousness Index developed by the Crime Research Centre (CRC) in Western Australia. The CRC Index was developed based on research conducted into public perceptions of offence seriousness and consideration of legislated sentences. The CRC Index was first developed in 1991, and subsequently reviewed in 1998 following the introduction of the Australian Standard Offence Classification (ASOC), the precursor of the ANZSOC.

The ABS developed the NOI by building on the 1998 version of the CRC Index, using data from the 2001-02 Higher Criminal Courts collection to refine the ordering by seriousness. The severity of sentences handed down to adjudicated finalised defendants were analysed to establish a principal offence for defendants. Consultation with practitioner and advisory groups in crime, courts and corrective services, resulted in further changes to the ranking of selected offences. Use of the NOI resulted in significant data quality improvements and increased ease of analysis, particularly with respect to the representation of multi-offence or global sentencing in criminal courts statistics. The NOI was first applied in the ABS 2001-02 Criminal Courts collection. For further information regarding the development of the NOI refer to Appendix 5 in Criminal Courts, Australia, 2001-02 (cat. no. 4513.0).

The NOI was reviewed in 2008-09 following the release of the second edition of ASOC (2008) to ensure the continued compatibility between the ASOC and the NOI and to reflect a changed profile and perceived seriousness of some offences.

The NOI is now used in a range of ABS crime and justice collections and is available for use more broadly by other agencies that produce statistical data.

2018 revisions to the structure of the NOI

The primary difference between this publication and the previous version of the NOI is the treatment of supplementary codes in the ANZSOC. These are broad level codes used in situations where there is insufficient information to code to the Group level (for example, 0800 - Theft, not further defined).

In the 2009 version of the NOI, a ranking was not assigned to a supplementary code if the other offences of that Subdivision or Division were not ranked sequentially, that is they differed in their perceived seriousness. For example, there is a substantial difference in perceived seriousness between 1011 - Import Illicit Drugs (ranked 14 in the NOI), and 1042 - Use Illicit Drugs (ranked 125), and as such the supplementary code at the Division level for Illicit drug offences (1000 - Illicit drug offences, not further defined) was not assigned a NOI ranking. In practice, the use of unranked offences often resulted in an offender / defendant being assigned a principal offence of ‘unknown’ in the ABS collections, which was not a useful outcome for data users.

In order to rectify this, the ABS has produced this revision to the NOI, which assigns rankings to the remaining supplementary offence codes that were previously unranked.

Methodology used to assign rankings for supplementary codes

Supplementary codes were assigned a ranking immediately following the lowest ranked ANZSOC Group level offence within that same ANZSOC Subdivision and/or Division. As an example, Figure 1 below illustrates the rankings of Group level offences for ANZSOC Division 03 - Sexual assault and related offences. As can be seen, the supplementary code 0300 - Sexual assault and related offences, n.f.d. has been assigned the NOI ranking immediately following the lowest ranked Group level offence.

Figure 1: Excerpt of the NOI, showing the inclusion of the supplementary codes for ANZSOC Division 03 - Sexual assault and related offences.

Figure 1: Excerpt of the NOI, showing the inclusion of the supplementary codes for ANZSOC Division 03 - Sexual Assault and Related Offences.

Figure 1: Excerpt of the NOI, showing the inclusion of the supplementary codes for ANZSOC Division 03 - Sexual assault and related offences.

This image shows group level offences for ANZSOC Division 03 in the right column and their corresponding 2018 NOI Ranking in the left column. ANZSOC code 03011 - Aggravated sexual assault has NOI ranking 7, Code 0321 - Non-aggravated sexual offences against a child has ranking 8, Code 0323 - Sexual servitude offences has ranking 9, Code 0322 - Child pornography offences has ranking 10, Code 0312 - Non-aggravated sexual assault has ranking 11, Code 0310 - Sexual assault, n.f.d has ranking 12, Code 0329 - Non-assaultive sexual offences, n.e.c has ranking 13, Code 0320 - Non-assaultive sexual offences, n.f.d has ranking 14, Code 0300 - Sexual assault and related offences, n.f.d has ranking 15. In addition, ANZSOC codes 0310 Sexual assault, n.f.d, 0320 Non-assaultive sexual offences, n.f.d and 0300 Sexual assault and related offences n.f.d have an arrow identifying them as Supplementary codes.

Related classifications - ANZSOC

The ANZSOC has been developed for use in the compilation and analysis of crime and justice statistics in Australia and New Zealand, and to improve the comparability of crime and justice statistics between Australian jurisdictions. The primary purpose of the ANZSOC is to provide a systematic way of organising criminal offences defined in the criminal laws of Australian state and territory jurisdictions. The ANZSOC defines an offence as any criminal act or omission by a person, persons, organisation or organisations for which a penalty could be imposed by the Australian legal system. The definitions of categories have been specifically chosen to minimise any confusion as to the boundaries of each category. As a result, the content of each category can be valid across jurisdictions, despite differences in legislation.

The ANZSOC is a classification structured with three levels: Divisions are represented by two digit codes (the broadest level of detail); Subdivisions are represented by three digit codes (the intermediate level); and Groups are represented by four digit codes (the finest level). At the Division level, the main purpose is to provide a limited number of offence categories that provide a broad overall picture of crimes experienced by victims or committed by offenders. The Subdivision and Group levels provide increasingly detailed dissections of these offence categories for the compilation of more specific and detailed crime and justice statistics.

The ANZSOC also has additional codes called 'supplementary codes' to cater for instances where there is insufficient information to code to the four digit Group level. Supplementary codes are created by taking a three-digit Subdivision code and adding a single zero to create a four digit code. Instances where a Subdivision cannot be selected, the most suitable Division is selected and two zeros are appended to its code to create a four digit code.

More information about the ANZSOC can be found in Australian and New Zealand Standard Offence Classification (ANZSOC) (cat. no. 1234.0).

Data downloads

Data files

Previous catalogue number

This release previously used catalogue number 1234.0.55.001.

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