Measuring BPS results

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This page provides details about the calculation, data sources and rules used to produce the reducing crime measures.

New Zealand population & youth population statistics

Source: Statistics New Zealand population estimates (external link)

Each of the reducing crime measures is a rate. Using rates removes the impact of population changes on data and allows people to analyse non-population changes in statistics.

The total recorded crime and violent recorded crime measures use the total New Zealand population as a base. The youth crime measure uses the total youth population (aged 14 to 16 years) as a base.

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Total recorded crime

We measure changes in total recorded crime using the official recorded crime rate. This is the number of recorded crimes per 10,000 people in the New Zealand population. The total recorded crime rate excludes traffic offences.

Source: NZ Police operational data.

Calculation: The total recorded crime rate per 10,000 people = (the number of recorded crimes / the number of people in the New Zealand population) x 10,000.

Notes: The operational data used for this measure differs from the Tier 1 recorded crime statistics (external link) published on the Statistics NZ website up to 2014. The Tier 1 recorded crime statistics exclude any historic crimes reported in that period. The operational data used for BPS includes all crimes recorded in the period, including any historic crimes. This means that the operational data used for the BPS measurement will show a higher number of recorded crimes than the official Tier 1 recorded crime statistics. For example, for the year end June 2011 the Tier 1 recorded crime statistics show 416,324 offences, and the operational data used for this measure show 432,911 offences.

It is important to note that recorded crime is not a count of all crime in New Zealand. Some offences are not reported to police, and are therefore not recorded by police. To ensure we have a broader picture of crime in New Zealand, we also monitor other measures of crime and victimisation, such as those included in the New Zealand Crime & Safety Survey

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Violent recorded crime

We measure the violent recorded crime rate using a subset of the total recorded crime rate. This is the number of violent crimes recorded, per 10,000 people in the New Zealand population.

Source: NZ Police operational data.

Calculation: The violent recorded crime rate per 10,000 people = (the number of violent recorded crimes / the number of people in the New Zealand population) x 10,000.

Definition: Violent crime is defined as:

  • homicides and related offences (attempted murder, manslaughter), including driving causing death where this results in a manslaughter charge
  • acts intended to cause injury (for example, serious assaults), and
  • offences against the person (including kidnapping and abduction, robbery, and other related offences).

These offences are defined using categories in the Australian and New Zealand Standard Offence Classification (external link) .

Less serious offences such as harassment (largely acts of intimidation) and blackmail and extortion (such as fraud) are excluded from this measure.

We also report two supporting measures of the violent recorded crime rate:

  • violent recorded crime rate in a private dwelling
  • violent recorded crime rate in a public place.

These are calculated from the number of violence crime occurring in each scene type (dwelling, public place or other).

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Youth crime

We measure the youth crime rate as the number of first appearances in court of young people, aged 14 to 16 years, per 10,000 young people in the New Zealand population.

Source: Ministry of Justice operational data.

Definition: The measure includes young people aged 14-16 at the time of the offence.

The measure counts the first court appearance for a criminal charge on a given day.

It does not count subsequent appearances on the same matter(s). It does cover future first appearances of the same person on different charge(s).

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Re-offending

We measure re-offending in two ways:

  • the rate of re-imprisonment = the rate of re-imprisonment for people leaving prison, within 12 months of their release
  •  the rate of reconviction =  the rate of reconviction for community-sentenced offenders, within 12 months of starting their sentence. 

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Re-imprisonment

Source: Department of Corrections operational data.

Calculation: Total offenders re-imprisoned / total number of offenders in the annual cohort.

Definition: The rate of re-imprisonment measures those prisoners in an annual released cohort (that is, all sentenced prisoners released between 1 April and 31 March) who are re-imprisoned for a new offence committed within 12 months of the individual’s release date.

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Reconviction

Source: Department of Corrections and Ministry of Justice operational data.

Calculation: Total offenders reconvicted / total number of offenders in the annual cohort.

Definition: The rate of reconviction measures those in an annual cohort of ‘new starts’ (that is, all offenders starting a new community sentence between 1 April and 31 March) who are reconvicted for a new offence committed within 12 months of the individual’s sentence start date.

Notes: Both indicators exclude reconvictions and re-imprisonments for administrative-type offences. Also excluded are reconvictions which result in sentences not administered by the Department of Corrections (for example, fines, and convicted and discharged)

We also report a supporting measure for the number of re-offenders. This rate is a combination of the total offenders re-imprisoned and total offenders reconvicted.

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