Top judges will be asked how they could use cutting-edge computer data modelling that will indicate what will happen to criminals depending on the severity of punishment.

PricewaterhouseCoopers has been contracted to help develop statistical modelling that could have a big influence on how harsh sentences are.

Launching the "investment approach to justice" in Wellington this morning, Justice Minister Amy Adams said she expected the work to be "quite revolutionary".

The work will use Statistics NZ's Integrated Data Infrastructure (IDI), which provides recently-linked data from the tax, benefit and justice systems, and anonymised information on all convicted offenders.

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Early work using the database has resulted in judges being told that in certain cases a fine could be a better option than community work, after analysts found criminals getting the latter were more likely to reoffend and rely on the dole.

Offenders given community work were found to be 4 to 7 percentage points more likely to be reconvicted within two years, compared with offenders who were fined.

Speaking to the Herald about those results in February, Ms Adams said such work could radically change the way policymakers, judges and the general public think about the balance between rehabilitation and punishment.

This morning, she was careful when asked how such analysis could influence judges' decisions.

"Judges are entirely independent and it would be absolutely wrong for me to try and tell them or direct them as to what to use. But, certainly, I think the more information that is available in any situation to a decision maker is a good thing."

Ms Adams said she would talk to the heads of benches to determine how they would like to use and receive any analysis of sentencing, and later outcomes in criminals' life.

"The feeling I have is the judiciary in New Zealand are absolutely driven by the same motivation that we are, which is they are frustrated with seeing the same behaviours occurring time and time again, with seeing revictimisation of the same people occurring time and again, and the same issues coming before their courts.

"They are looking for ways that they can break that cycle."

Finance Minister Bill English is championing the use of the powerful Statistics NZ database to try and work out which young people are at risk of poor outcomes later in life, and whether Government spending is making a real difference.

Such work will have a significant impact on decisions in this month's Budget.

In the justice area, changes to investment will be targeted at young people.

Analysis already carried out showed that after the age of 22, most of the opportunity to prevent offending is lost.

"Investment briefs" will be produced as part of the investment approach. One released today highlighted the "strong" need for more cognitive-behavioural therapy to be available for young offenders.

Providing more of the psychological treatment will cost between $5000 and $20,000 per person given treatment, the brief states. For every five to 15 offenders getting treatment, one less will reoffend.

However, the brief also highlights some of the hurdles that will be faced before any changes can be made. The health sector has reported a current shortage of psychologists, and the Ministry of Health has advised that mental health services "are under significant demand pressure so there would be very limited scope to shift their focus towards reducing offending".

Ms Adams said she and other ministers were now committed to look at funding decisions not only by health, education or another portfolio.

"Our best opportunity to work with these young people is long before they end up anywhere near the criminal justice system. I think the change in thinking for me is when we are looking at interventions and spending, most of the interventions I am now lobbying for as the justice minister don't happen in my sector.

"The interventions I am usually lobbying for to benefit the justice sector are interventions in health, interventions in education, interventions in CYF.

"It is about getting education to not simply think of their success through an educational lens, and to regard their success as partly how many of those kids end up in prison."

TOO MANY PEOPLE IN JAIL- ADAMS

New Zealand's high incarceration rate must be addressed, Justice Minister Amy Adams said.

Speaking at the Ministry of Justice's offices today, Ms Adams said that, despite falling crime rates, New Zealand's imprisonment rate per capita was high by international standards.

In 2014/15 New Zealand imprisoned 194 people out of every 100,000 people - placing us seventh highest in the OECD just behind Mexico.

"We're 27 per cent higher than Australia and 40 per cent higher than the UK. The current rate of imprisonment for Maori is much worse, standing at around 700 per 100,000 people.

"While having the right people behind bars to protect the public is a good thing, it comes at a tremendous cost and we need to work hard to keep bringing the number of people committing these offences down."

CRIME STATISTICS

As part of the "investment approach" to justice, launched today, analysts looked at crime statistics.

• One in three men born in 1978 now have a criminal conviction. That rate is far worse for Maori and Pacific men -- one in two have a criminal conviction.

• Half of all offending happened when people were 17-22 years old.

• Three per cent of adults experience 53 per cent of all crime.

• Eleven per cent of the general public have used mental health services. This compares with 35 per cent of those proceeded against by police, and 51 per cent of those starting a community sentence.