Contribution to Population Change by Component

Using the ‘mover-stayer’ data from the internal migration maps, this set of maps provides direct comparison of the contribution of each component to the Census Usually Resident Population Counts (CURP) at each Census, for each territorial authority area. Each component is shown as a percentage of the CURP at the end of each period.

Key Observations:

  • Stayers comprise the largest proportion of each Census Usually Resident population, generally accounting for around two-thirds to three-quarters, although values are somewhat lower for two high mover population outliers (Queenstown-Lakes District and Selwyn District). Across the three censuses the percentage of each population categorised as ‘Stayers’ was generally highest at the 2013 census (true for 57% of territorial authority areas), but it has also remained remarkably similar for each area over the observed period.
  • The percentage of each population categorised as Internal Arrivals typically accounts for the second largest component of each Census Usually Resident population. Across the three censuses this component was generally lowest at the 2013 census, when 72 per cent of all territorial authority areas experienced their lowest proportion. The highest proportion for all four censuses was experienced by Selwyn District, and the lowest proportion consistently by Auckland.
  • The percentage of each population categorised as Overseas five years ago was generally highest at the 2006 Census. This was the case for two-thirds of all territorial authority areas. The highest proportion has consistently been for Queensland-Lakes District.
  • The percentage of each population categorised as not born five years ago was generally lowest at the 2018 Census. This was NOT the case for only ten territorial authority areas (15%).
  • The main mover origins and destinations of each individual Region and TA are often identical, as they are also across each period, and often account for similar proportions of movers in each direction. It would seem that the majority of New Zealand movers move within relatively narrow geographic areas, and that these areas may coincide with labour market regions (Papps and Newell 2002).

'Mover-Stayer' Methodology

Census Usually Resident Population Counts (CURP) were originally sourced from Statistics New Zealand (2014, 2020) and are based on the Census question ‘where did you usually live five years ago?’ Because some people fail to provide this information on their census form, a methodological decision was made to prorate the data for those people according to the local (regional or territorial authority area) distribution for those whose address five years ago was stated (see caveat below).

Data for people who gave both their current and past address were categorised as either:

  • Stayers (people living in the same region or territorial authority area at both censuses—although they may have moved elsewhere within that area, and/or out of the area and back in, between the censuses);
  • Internal Arrivals (people living in the specified region or territorial authority area who lived elsewhere in New Zealand five years ago);
  • Internal Departures (people who lived in the specified region or territorial authority area five years ago, but now live elsewhere in New Zealand) - NB not shown on these maps;
  • Overseas Arrivals (people who were living overseas five years ago);
    • or
  • Not Born Five Years Ago (children aged 0-4 years, born since the previous census and whose address five years ago cannot therefore be determined).

Those who did not provide their current and/or previous address are recorded at the various censuses as either 'living elsewhere in NZ/not further defined', 'not elsewhere included/address five years ago not stated' or ‘unable to match’ (hereafter ‘Unmatched’. Unmatched data were prorated across ‘known’ migration as follows:

  • Stayers in each region or territorial authority area, Arrivals from each other region or territorial authority area, and Arrivals from Overseas were summed and their distribution calculated as a percentage. This percentage was then applied to the ‘unmatched’ number and the resulting number added to the number having stated their previous residence.

    Leavers (Departures). The database is set up as a matrix, with area of usual residence 5 years ago juxtaposed against area of usual residence at each census. The resulting (prorated) Internal Arrival numbers to each territorial authority or regional council area simultaneously become Internal Leavers from those areas, based on their address 5 years ago.

Caveat: The methodological assumption that people who ‘lived elsewhere in New Zealand/not further defined’, ‘not elsewhere included/address five years ago not stated’ or ‘unmatched’ have the same mover-stayer distribution as those who did specify their previous address may be incorrect. We took this approach because it is preferable to calculating movements based on ‘known’ previous residence only, as these proportions differ substantially for each region and territorial authority area. The resulting data should thus be viewed as a best approximation of the situation and will differ slightly from the raw data that Statistics New Zealand publishes, and other analysts may generate.

  • Mover-Stayer Methodology (Summary)
  • 1. TA/RC of usual residence (time t+5) by TA/RC of usual address five years ago (time t) are juxtaposed in a matrix
  • 2. Stayers, Internal Arrivals, and Overseas Arrivals are summed and their % distribution calculated
  • 3. Not Specified/Inadequately defined/New Zealand not further defined/unable to match are prorated
  • 4. Prorated data are added to 'known' Stayers and Movers
  • 5. Internal Arrivals (prorated) = the sum of Arrivals from all other TA/RC areas (CURP at t+5 years minus Stayers),
  •     Internal Leavers (prorated) = Sum of Usual Residence at time t minus Stayers
  • 6. Net Internal Migration at time t+5 = Net Internal Arrivals minus Net Internal Departures

Additional reading

Braybn L and NO Jackson (2019) A new look at population change and regional development in Aotearoa New Zealand. New Zealand Geographer 75: 116-129. DOI: 10.1111/nzg.12234

Braybn L, NO Jackson, G Stichbury, T McHardie (2019) Visualising and Communicating Population Diversity through Web Maps. New Zealand Population Review 45: 46–66

Jackson NO (2017) ‘Introduction and overview’ Policy Quarterly Supplement 13: 3-9.

Jackson NO and L Brabyn (2017) The mechanisms of subnational population growth and decline in New Zealand, 1976-2013’ Policy Quarterly Supplement 13: 22-36. http://igps.victoria.ac.nz/publications/PQ/2017/PQ-Vol-13-Supplementary-2017.pdf.

Papps KL and JO Newell (2002) Identifying Functional Labor Market Areas in New Zealand: A Reconnaissance Study Using Travel-to-Work Data. IZA Discussion Paper No. 443, Available at SSRN: https://ssrn.com/abstract=304439.

Preston K, D Maré, A Grimes, S Donovan (2018) Amenities and the attractiveness of New Zealand Cities. Motu Working Paper 18-14. Motu Economic and Public Policy Research.

Data Sources

Statistics New Zealand (2020) Customised Database, Area of Usual Residence (2018) and Usual Residence 5 Years Ago (2013) by Age Groups for the Census Usually Resident Population Count 2018

Statistics New Zealand (2014) Customised Database, Area of Usual Residence (2006 and 2013) and Usual Residence 5 Years Ago (2001 and 2008) by Age Groups for the Census Usually Resident Population Count, 2006 and 2013.