The data from the Census is being used by the Representation Commission to set new electorate boundaries, which makes sure each electorate has about the same number of people.
An electorate cannot be more than 5% larger or 5% smaller than its population quota.
Half of South Island electorates, and a fifth of North Island are either 5% larger or 5% smaller than the set quotas of 64,899 for the North Island and 65,458 for the South Island, which has 16 electorates as set by the Electoral Act 1993.
The electorates in the South Island that are set to get larger are the Dunedin South electorate, which is below the quota by -6.6%, Invercargill (below quota by -6.3%), Ilam (below quota by -6.1%), West Coast-Tasman (below quota by -6.0%), and Dunedin North (below quota by -5.8%).
The changes would likely make Dunedin North and South include more rural areas.
The electorates in the South Island set to get smaller are Waitaki, which exceeds the quota by 11.1% and Clutha-Southland, which exceeds the quota by 7.9%.
Extra seat for North Island
There will be an extra electorate seat in the North Island at the 2020 election and roughly one-third of electorate boundaries will change as a result of population growth in Census 2018.
The Representation Commission will decide by April where the new seat will be.
The new data released today by Stats NZ means the number of general electorates increases from 64 to 65, the number of North Island general electorates increases from 48 to 49 and the number of Māori electorates remains at seven.
Stats NZ has confirmed one in six New Zealanders didn't complete a questionnaire "largely due to operational failures that made it difficult for them to participate''.
To address high levels of non-response, Stats NZ for the first time used alternative government data to fill the gaps.
But while Stats NZ gave itself a high quality rating for ethnicity data collected, the Data Quality Panel has lowered it to moderate.
The panel endorsed Stats NZ's decision not to publish iwi data due to the insufficient quality and noted "in this regard Stats NZ have not met their Treaty obligations to Māori" .
There is no change in the number of Māori electorates as a result of the Census data.
Household and families data collected was of a low quality meaning comparisons can't be made with the last Census in 2013.
Information that relates people to dwellings was also incomplete as just 8% of the population can't be placed in a specific dwelling.
With ODT
