Deputy Prime Minister Winston Peters says there needs to be more substance behind a new crime survey designed by the Ministry of Justice, reviewed by police and statistics experts and described as "the most comprehensive report ever undertaken into the true nature of crime in Aotearoa".

Peters was asked today about the findings of the new New Zealand Crime and Victims Survey.

Its results, from face-to-face interviews with 8000 randomly selected New Zealanders, were released today.

It found that 77 per cent of crime went unreported to police, with many victims unaware they had been the victims of a crime.

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The annual survey, the first of three, will provide information to the Government's much-vaunted Living Standards Framework and list of wellbeing indicators.

Its data will also be used by the Ministry of Justice, Stats NZ, Ministry of Social Development, Te Puni Kokiri, the Police, Department of Corrections, Oranga Tamariki and the Ministry for Women.

Peters was asked at the weekly post-Cabinet press conference, which he fronted in the absence of Prime Minister Jacinda Ardern, whether that figure concerned him.

Instead, he questioned the research behind it.

"If it went unreported, how can you with accuracy know it was 70 per cent?"

"I'm asking you a very, very significant question. I know what the media wrote, but if it's unreported how can you know that 70 per cent is a fact?"

When a reporter pointed out it was a Ministry of Justice survey using Stats NZ methodology and self-reported by respondents, Peters said he wasn't questioning its accuracy but rather whether the media thought it was accurate.

"I'd like to have a touch more substance behind that sort of research than what I'm reading," he said.

The survey, which is costing $3 million to carry out, is the only source of information about unreported crime and victimisation, according to a Ministry of Justice fact sheet.

"Only 23 per cent of crime is reported to the police. The New Zealand Crime and Victims Survey findings will be a very valuable resource that will be used frequently by policy analysts, researchers and other staff at a range of Government agencies," the fact sheet says.

The survey, which replaces the previous New Zealand Crime and Safety Survey, was designed by research and evaluation staff at the Ministry of Justice and reviewed by Stats NZ and the NZ Police.

A total of 13 Government and NGO organisations were consulted on it and it was reviewed by Victoria University and by international criminology expert Pat Mayhew OBE, who serves on the UK Statistics Authority's Crime Statistics Advisory Committee.

A pilot was done to test the methodology, and experts from the police and Victoria University provided quality assurance advice. Independent research company CBG Health Research carried out the survey.

Peters eventually said the figure was unsatisfactory and suggested people thought it was a waste of time to report crime to police.

"That's why we need 1800 more frontline police men and women, which we're bringing in as fast as we possibly can, with 445 back-up staff."

Peters also questioned immigration data reported by the Herald recently.

It reported that net migration was about 61,600 people a year, close to the 64,000 peak it hit under National in 2016.

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"I pick up the New Zealand Herald in the last few days and see all sorts of figures on immigration without any exactitude as to what it all means," Peters said.

"Here we are in May 2019 where we need far better research than that. I've been reading figures from the Ministry of Immigration for years too and I know they're not accurate."