Justice Sector Datalab


Glossary Explore Data


This page gives information about the statistics in each page of the Justice Sector Datalab.

Click one of these to go directly to:

Recorded Offenders
Adults convicted in court
Prison Population Snapshot 

About the Recorded Offender data

These data are derived from New Zealand Police's Recorded Crime Offenders Statistics - proceedings. It counts proceedings against alleged offenders recorded by NZ Police, except for the following offences:

These data are updated quarterly. 

Age group

The age group of the alleged offender at the time they were proceeded against by Police.  'Organisation' means that the offender was an organisation (eg a company). 'Not specified' is used when the age is unknown, was not stated or was inadequately described. 

Note that some alleged offenders coming to the attention of Police are children. Children (under the age of 14) cannot be prosecuted (except for the offences of murder and manslaughter). In other cases where children's offending causes concern, they may be dealt with by warning, Police diversion or a Family Group Conference. Alternatively they may be referred to Oranga Tamariki as in need of care and protection and, if necessary, issues of the care and guardianship of these children can be dealt with in the Family Court. In this dataset these actions are allocated the Method of Proceeding 'Non-court action'.


Sex is classified as one of four categories. In addition to 'male' and 'female', a 'not applicable' category is used where the alleged offender may be an organisation, and a 'not stated/inadequately described' category for instances where the sex is unknown or indeterminate. 


The ethnic group of the alleged offender.

Police record an alleged offender's ethnicity where it is known. The recorded ethnicity is the one that a person identifies with most strongly. Recording an alleged offender's ethnicity may be difficult in some cases.

Measures of ethnicity can be influenced by the context in which they are collected. One of the reasons for this is that a degree of subjectivity is often involved. In a policing context this is particularly problematic, as alleged offenders may not be cooperative or coherent. Police ethnicity data is carried through to conviction and sentencing statistics.

Ethnicity classifications used within the Recorded Crime collections differ from classifications used in other government collections which use the 2005 ethnicity standard. No allowance is made for people wanting to specify more than one ethnic group, which may distort or bias ethnic group statistics. Use caution when attempting to combine data from different sources to form estimates of offending rates (per head of population) for specific ethnic groups.

Note that businesses and corporate organisations have 'Organisation' in the ethnicity field. 

Method of proceeding

The method of proceeding describes the first type of legal action (court or non-court) initiated by police against a person as a result of an investigation of an offence(s). Non-court actions include (but are not limited to) informal and formal warnings, diversion, and for children and young people, family group conferences.

If multiple proceedings are taken against an alleged offender on one day, this field shows the method of proceeding for the most serious offence for which an alleged offender is proceeded against by court and non-court action.  


The most serious offence for which an alleged offender is proceeded against by court and non-court action. The nature of the offence is described using the ANZSOC group classification. 

About Adults Convicted in Court

The data in the Explore Adults Convicted in Court section are based on publicly available statistics released by the Ministry of Justice, via Statistics New Zealand's NZ.Stat tool.

Data shows the number of adults (aged 17 years and over) convicted in the District and High Courts of New Zealand each year.

A person can be convicted of more than one offence in court in a year. Here we count only their most serious conviction - based on the sentence they received and the seriousness of the offence.

These data are updated every six months.

More information about the data can be found on Statistics New Zealand's website (external link). 

Service Delivery Area

There are more than 60 District Courts in New Zealand. To manage service delivery at the courts and to make our data and trends easier to analyse, we group them up into 14 Service Delivery Areas (SDAs), similar to regions. To see which courts are assigned to each SDA, see this page on Statistics New Zealand's website (external link).


Different criminal offence types are grouped into 16 categories based on the Australian and New Zealand Standard Offence Classification (ANZSOC). They order from the most serious offences such as Homicide and related offences, through to the less serious, such as Offences against justice procedures.

Read more at Statistics New Zealand's website (external link).


Year is based on the date on which the person was convicted in court. Data on this site is updated every six months, for June and December years, so the year format updates with every release. For example, the year ending on 30 June 2013 is presented here as 2012/13 or 12/13. In alternate releases, calendar years ending on 31 December, are presented as 2012, 2013 and so on. 


A person can receive more than one sentence for a single conviction. Only their most serious sentence is counted in this data. The Sentencing Act 2007 introduced a number of new sentences, including home detention. So some sentence types will not appear prior to 2007.

Read more at Statistics New Zealand's website (external link).

Age group

Age is calculated at the date the offence was committed. This data only covers adults aged 17 and years and over. Ages are grouped as follows: 17-19, 20-24, 25-29, 30-39 and 40 years and over. In some cases, where a person's date of birth is not recorded and/or the date the offence was committed is not recorded, the age is set to Unknown.

Gender and ethnicity

Gender and ethnicity are usually recorded by Police at the time a person is apprehended. Only one ethnicity is collected per person. If the person's gender or ethnicity has not been recorded, it is set to Unknown.

Random-rounding method used 

The standard version of Statistics NZ's method of base 3 random rounding is applied to protect the confidentiality of individuals. Identifying details are also removed, and data are aggregated. Due to rounding, individual figures may not always sum to the stated total(s).


About the Prison Population Snapshot

This is a snapshot of the New Zealand prison population, showing all people in New Zealand correctional facilities on the last date of each quarter (31 March, 30 June, 30 September, 31 December). These data are updated quarterly.

 Note that these differ from the statistics published on Statistics New Zealand's NZ.Stat tool, which shows annual remand and sentenced prison populations. 

Gender, age and ethnicity

Information on the gender, age and ethnicity of an offender is recorded by Corrections. Age is calculated based on the birth date as collected by the prosecuting authority (mostly New Zealand Police) at the time a person is arrested or prosecuted. 

Sentence/ remand

This field records whether  at the time of the snapshot a prisoner had been sentenced  ('Sentenced'), was on remand awaiting sentencing ('Remand - convicted') or was remanded in custody awaiting trial ('Remand - accused').

Prison location

The location at which the prisoner is held at the time of the snapshot.  This list includes prisons which have now closed, such as Mt Eden Men's Prison.  

Length of sentence or remand

The length of sentence or remand is based on the actual time spent in prison, not the court-imposed length. This excludes time served on remand.

Security classification

Corrections assesses each incoming prisoner and assigns them to a security classification so that they can be housed appropriately. Prisoners are classified according to the level of risk posed by that prisoner while inside or outside prison, including the risk that escape would pose to the public. Most categories are self-explanatory; 'Low-medium' means that a prisoner is classified as low risk inside the prison, but poses a higher external risk.  From September 2015, remand prisoners were classified as 'Remand' or were 'Unclassified'.  Prior to this, all remand prisoners were 'Unclassified'.  For more information see the Security Classification page of the Prison Operations Manual (external link).


Contact us

If you have any comments, queries or suggestions for this site please contact us via email at: justiceinfo@justice.govt.nz.