The number and type of electorates for New Zealand's parliamentary elections is influenced by the results of Census and the Māori Electoral Option.
The five-yearly Census of Population and Dwellings counts the population usually living in New Zealand, including children and those not eligible to enrol to vote.
This information is used by the Government Statistician to calculate the following groups:
- Māori electoral population
- General electoral population - North Island
- General electoral population - South Island
The Māori electoral population is calculated using a statutory formula. This population includes:
- persons registered as electors of Māori electoral districts
- plus a proportion of persons of Māori descent who are not registered as electors
- plus a proportion of persons of Māori descent who are under the age of 18.
The General electoral population is the ordinarily resident population shown in the last census less the Māori electoral population.
All electorates must have about the same population size. The number of South Island General electorates is fixed at 16 by the Electoral Act 1993. To calculate the number of electorates the Government Statistician:
- divides the South Island General electoral population by 16 (this result provides the average electoral population for South Island electorates and is referred to as the South Island quota)
- divides the Māori electoral population by the South Island quota to work out the number of Māori electorates, and
- divides the North Island General electoral population by the South Island quota to work out the number of General electorates for the North Island.
The number of Māori and North Island General electorates are rounded to the nearest whole number.
More information about how Statistics New Zealand calculates electoral populations and the number of electorates is available at www.stats.govt.nz.