Final estimates of migrant arrivals, migrant departures and net migration for Regional Council areas, Territorial Authority areas and Auckland Local Board areas.
Collection of final subnational estimates
The collection of final subnational estimates of migrant arrivals, migrant departures and net migration is available for Regional Council Areas (16), for Territorial Authority Areas (67) and for Auckland Local Board Areas (21) from June 2014. Final subnational migration estimates are derived from integration of the movement records and Stats NZ Integrated Data Infrastructure (IDI) address notifications data. The subnational series also include a ‘Not stated’ category indicating estimates of migration for the period where geographic information is not available.
IDI address notifications data
The IDI is an integrated database that consists of de-identified administrative and survey datasets from a wide range of subject matter areas and sources.
Individuals' location information is accessible in the IDI in the form of a dataset containing their full address notification histories. When an individual engages with a service for the first time in New Zealand (such as health care, education, or tax services), or when a New Zealand resident notifies an agency of an address change, the address information is updated and subsequently added to the individual's address history in the IDI.
The IDI address notifications are ‘observational’ in the sense that an address is recorded when a person notifies an agency of a change of address. These observation points are dates of notification, and not usually the actual date of moving to a location. All sources are likely to have missing data or other quality issues, such as a supplied address becoming out-of-date when a person moves without notifying the agency. There are also differing time lags by respective agencies in compiling address notifications. These lags are generally unknown and may change over time.
Several key agencies contribute to the regular updates of address notifications for geocoding to meshblock geographic areas by Stats NZ. Each address notification includes an administrative reference date recorded by the agency. The sources collecting information on residential address and/ or notification of address change are:
• 2013 Census (Stats NZ)
• tax registrations (Inland Revenue)
• National Health Index and Primary Health Organisation enrolments (Ministry of Health)
• motor vehicle registrations and driver’s license registrations (NZ Transport Association)
• primary and secondary school rolls (Ministry of Education)
• ACC claims (Accident Compensation Corporation)
• working age benefits and superannuation (Ministry of Social Development).
Methodology for determining the NZ-location information in migration records
The geographic location of final records of migrant arrivals and departures is determined by a process that accesses integrated border movements (sourced from NZ Customs Service) and address notifications in the Stats NZ IDI (address_notification table compiled by Stats NZ IDI).
Final records of migrant arrivals and departures are integrated with their address notifications histories. The address notifications with associated notification dates closest to the migrant movement dates are selected as the NZ-residence location. Migrants may have address notifications recorded before and after the migrant arrival or departure date. The address notification closest to the movement date is selected irrespective of the time sequence of address notification in relation to the border movement.
The results in this collection are not official statistics They have been created for research purposes from the Integrated Data Infrastructure (IDI), managed by Stats NZ.
Access to the anonymised data used in this study was provided by Stats NZ under the security and confidentiality provisions of the Statistics Act 1975. Only people authorised by the Statistics Act 1975 are allowed to see data about a particular person, household, business, or organisation, and the results in this collection have been confidentialised to protect these groups from identification and to keep their data safe.
Careful consideration has been given to the privacy, security, and confidentiality issues associated with using administrative and survey data in the IDI. Further detail can be found in the Privacy impact assessment for the Integrated Data Infrastructure available from www.stats.govt.nz.