The Statistics Minister is accusing a National MP of playing "fast and loose" by discussing preliminary figures from Census 2018.
Statistics New Zealand's chief statistician Liz MacPherson has written a letter to MPs that says more than 700,000 people didn't take part in, or didn't fully complete, the census last year.
That is according to National MP Nick Smith. The letter has not been publicly released.
MacPherson had twice refused to reveal the number, and only did after being threatened with a complaint to the speaker.
MacPherson declined to comment, saying she won’t speak on the issue until April 29th when she will be making her official statement.
Minister James Shaw says that MacPherson was entitled to not reveal the number
"The Government Statistician has a legal duty to maintain the integrity of the official statistic system, and she has considerable independence over how to do that."
Shaw says the issue is that National MP Nick Smith wanted her to release information that was partial and out of context.
"That was the first time that that ever happened, as far as we can tell."
He has accused Smith of leaking the figures. Shaw says that Smith is playing "fast and loose" with numbers.
"Every Census has people who only partially complete the form, and every Census has people who don't complete the forms, and what he's done is added those figures together."
Shaw says the impact won't be known until the figures are ready to be released.
"That's why [MacPherson] was resisting releasing that information because it is very partial information completely lacking in context, and it ultimately may or may not have any impact on the quality of the Census data."
The previous Government was warned that participation in Censuses is declining, Shaw says, which is why the 2018 Census moved online for the first time.
He denies that the digital factor was not what has led to the lack of participation, with initial figures suggesting 80 per cent of people filled the forms out online.
"The reason why it is taking longer than it normally does to release census data is that Stats NZ are working to make sure that the quality of the information we get is as good or better than previous Censuses."