November 23, 2021

Counting the population without a Census

Statistics New Zealand Experimental Series

On the 31 August 2021, Statistics New Zealand released as an experimental series, an annual population count time series that runs from 30 June 2006 to 30 June 2020, constructed from administrative data sources available within Statistics New Zealand’s Integrated Data Infrastructure (IDI). 

This time series was produced as part of Statistics New Zealand’s census transformation programme, which explores the use of administrative data to produce demographic information for the entire population.

It is worth noting that given that the Census is run only every five years, an annual administrative time series, such as this, can ensure that many of the demographic variables contained in the five yearly Census are updated or estimated in a more timely fashion for those wanting to use such data.

In the initial release, only eight variables were included in the data release, these are:

  • Age
  • Sex
  • Geography
  • Ethnicity
  • Māori descent
  • Birthplace
  • Years since arrival in New Zealand.

While Statistics New Zealand plans to add further labour market, income and qualifications variables in the next few years, we currently only have the small number of variables already included.

In this article, I will look at an interesting way of using this new dataset.

In particular, I have used the birthplace or country of birth variable to look at the percentage share of people born overseas across New Zealand’s local authority areas (local district or city council areas), where people were born overseas, and how this has changed between 2006 and 2020. I have then mapped this data onto a map of New Zealand to produce the following map.

NZ migrant

In these maps we have the percentage share of people born overseas in each local authority area, for both 2006 and 2020. The data shows that in 2006 just four local authority areas had 20 percent or more of their population born overseas, with the average being 11.6 percent across the local authority areas. These four areas are:

  • Auckland (34.4 percent)
  • Wellington City (25.7 percent)
  • Queenstown-Lakes District (25 percent)
  • Porirua City (20 percent).

At the other end of the scale, there were three local authority areas in 2006, with less than five percent of their population born overseas:

  • Ōpōtiki District (4.7 percent)
  • Wairoa District (4.5 percent)
  • Chatham Islands (zero percent).

By 2020, the average percentage share of overseas people across the local authority areas has risen to 17.1 percent, with the number of overseas born in New Zealand rising from around 1.14 million people in 2006 to 1.59 million in 2020. In 2020, 18 local authorities have 20 percent or more of their population born overseas, including eight South Island local authorities and ten North Island local authorities. By 2020 just one local authority, the Chatham Islands still had less than five percent of its population born overseas with 3.5 percent.

Examining the change between 2006 and 2020, shows that no local authority experienced a decline in the percentage of people born overseas. The local authorities with the largest increase were:

  • Queenstown-Lakes District, which grew from 25 percent to 43.2 percent
  • Mackenzie District which grew from 12.8 percent to 23.9 percent
  • Ashburton District which grew from 10 percent to 19.8 percent
  • Hamilton City which grew from 19.8 percent to 29.1 percent
  • Central Otago District which grew from 8.8 percent to 17.9 percent.

At the other end of the scale, the local authorities with the smallest increases were:

  • Wairoa District growing from 4.4 percent to 5.8 percent
  • South Waikato District which grew from 11.1 percent and 13 percent
  • Kawerau District which grew from 7.2 percent to 9.2 percent
  • Whakatane District which grew from 10 percent and 12.1 percent
  • Stratford District which grew from 7.1 percent to 9.5 percent.

Interestingly all of these five districts are spread across the central part of the North Island.

Moving from New Zealand to the World.

I have mapped for both 2006 and 2020, the number of overseas born living in New Zealand by their country of birth, to see where people coming to New Zealand have come from. As we can see the following maps, there are few countries or territories from where people have not moved to New Zealand.

International 2006

Unsurprisingly, the countries supplying more than 50,000 people migrants to New Zealand in 2006, included Australia, the United Kingdom, and China. A further six countries are contained in the next bracket with between 20,000 and 50,000, included Fiji, India, South Korea, Western Samoa, South Africa, and Tonga. We can also see that there were a large number of countries with less than 500 people living in New Zealand in 2006, with many of these countries located in Africa, South and Central America, the Middle East, and Central Asia.


By 2020, the number of countries supplying more than 50,000 migrants to New Zealand had increased to eight, with Fiji, India, Philippines, Western Samoa, and South Africa joining Australia, the United Kingdom, and China. With most of the countries previously in the 20,000 to 50,000 bracket moving into 50,000 plus bracket, only four countries are in this bracket in 2020, with South Korea and Tonga, being joined by Malaysia and the United States of America.