Subnational Ethnic Population Projections 2013-base

Reference period

This release contains 2013-base projections for four broad and overlapping ethnic populations usually living in New Zealand's 16 regional council areas (regions), 67 territorial authority areas (TAs), and 21 Auckland local board areas (LBAs). Projections are available for: 'European or Other (including New Zealander)', Māori, Asian, and Pacific. Each ethnic population consists of all people who identify with ethnicities within that broad ethnic group. People who identify with more than one ethnicity are included in each ethnic population they identify with.

The projections supersede the updated 2006-base projections released in September 2010. The new projections have the estimated resident population of each ethnic group at 30 June 2013 as a base, and cover the period to 2038 at five-year intervals.

Consistency with other projections

These subnational ethnic population projections complement the New Zealand projections of ethnic populations (National Ethnic Population Projections: 2013(base)–2038) released on 21 May 2015. However, only the median projection (50th percentile) of the national ethnic population projections and the medium projection of these subnational ethnic population projections are directly comparable. Other percentiles or projections cannot be directly compared because the projection assumptions may be incompatible.

These subnational ethnic population projections also complement the projections of subnational total populations (Subnational Population Projections: 2013(base)–2043) released on 19 February 2015. However, only the medium projections of each are directly comparable. Other projections cannot be directly compared because the projection assumptions may be incompatible.

**Changes since the previous 2006-base projections **

Review of assumptions

Deriving the projections involves reviewing all projection assumptions for each area and each ethnic group. These subnational ethnic population projections are updated to incorporate the latest demographic information, notably the 2013-base Subnational Population Projections (released 19 February 2015) and 2013-base National Ethnic Population Projections) (released 21 May 2015), which both incorporated results from the 2013 Census of Population and Dwellings and subsequent population estimates. Birth and death registrations and international travel and migration data are also important data sources.

The changes in these subnational ethnic population projections from the previous 2006-base projections (September 2010 update) mainly relate to the base population and short-term migration assumptions.

Geographic classification

The population projections in this release are based on the regional council, territorial authority, and Auckland local board classifications and boundaries at 1 January 2015.

Projection assumptions

Projection assumptions are formulated after analysis of short-term and long-term historical trends, information provided by local planners, and government policy.

Base population

These projections have as a base the estimated resident population of each area and each ethnic group at 30 June 2013. This population was based on the census usually resident population count of each area and each ethnic group at 5 March 2013 and adjusted for:

• non-response to the census ethnicity question
• net census undercount
• residents temporarily overseas on census night
• births, deaths, and net migration between census night (5 March 2013) and 30 June 2013
• reconciliation with demographic estimates at ages 0–9 years.

The 'Estimated resident population (ERP), adjustments to derive ERP at 30 June 2013 (from census usually resident population)' table in NZ.Stat summarises the ERP, and adjustments to derive ERP, for each area and each ethnic group.

Fertility and paternity

New birth cohorts are added to the population by applying fertility assumptions to the female population of childbearing age (12–49 years) and paternity assumptions to the male population (15–54 years). The paternity rates allow for births that men of a given ethnic group have with women not of that ethnic group. For example, Māori paternity rates allow for births that Māori men have with non-Māori women.

The assumed fertility and paternity rates for each area and each ethnic group are based on the registered births during the period 2013–15, and change that is consistent with the fertility and paternity assumptions from the National Ethnic Population Projections: 2013(base)–2038. Under the national median assumption, the total fertility rate decreases between 2014 and 2038 for the:

• 'European or Other' population from 1.91 to 1.85 births per woman
• Māori population from 2.47 to 2.20 births per woman
• Asian population from 1.64 to 1.60 births per woman
• Pacific population from 2.75 to 2.30 births per woman.

Under the national median assumption, the total paternity rate decreases between 2014 and 2038 for the:

• 'European or Other' population from 0.14 to 0.13 births per man (with non-European and non-Other women)
• Māori population from 1.02 to 0.90 births per man (with non-Māori women)
• Asian population from 0.18 to 0.15 births per man (with non-Asian women)
• Pacific population from 1.01 to 0.90 births per man (with non-Pacific women).

The fertility and paternity assumptions are derived for the purpose of projecting each population and should not be used as a precise measure of fertility or paternity differentials between areas or ethnic groups.

The projections allow for births to parents of each ethnic group that are not registered as children of that ethnic group. The medium assumed loss factor is 1.8 percent for 'European or Other', 4.0 percent for Māori, 2.4 percent for Asian, and 3.2 percent for Pacific, based on national-level data for 2006–14.

The low and high assumptions for fertility rates, paternity rates, and the loss factor are chosen to represent plausible alternative fertility and paternity scenarios for each area and each ethnic group.

The projections allocate births between male and female. A sex ratio at birth of 105.5 males per 100 females is assumed for each area and ethnic group, based on national-level data for 1996–2014.

Mortality

Mortality assumptions are applied to each age-sex group to allow for deaths. The assumed mortality rates for each area and ethnic group are based on registered deaths for each area during the period 2013–15, and change that is consistent with the mortality assumptions from the National Ethnic Population Projections: 2013(base)–2038. Under the national median assumption, period life expectancy at birth increases between 2014 and 2038 for the:

• 'European or Other' population from 80.7 to 85.0 years for males, and from 84.2 to 88.3 years for females
• Māori population from 73.4 to 81.3 years for males, and from 77.3 to 84.7 years for females
• Asian population from 84.8 to 88.7 years for males, and from 87.2 to 91.1 years for females
• Pacific population from 74.6 to 82.1 years for males, and from 78.8 to 85.8 years for females.

The mortality assumptions are derived for the purpose of projecting each population and should not be used as a precise measure of mortality differentials between areas or ethnic groups.

The low and high mortality assumptions are chosen to represent plausible alternative fertility and paternity scenarios for each area and each ethnic group.

Migration

Migration assumptions are applied to each age-sex group to allow for net migration (arrivals minus departures). Migration at the subnational level has both an internal (to/from other areas of New Zealand) and an external (to/from overseas) component, although these separate components are difficult to quantify. For example, ethnicity is not collected in external migration data. The assumed net migration levels and age-sex patterns for each area and ethnic group are based on a consideration of:

• observed net migration during each intercensal period from 1996 to 2013
• the capacity of each area for further growth (for areas with net inflow)
• whether historical outflows can be sustained (for areas with net outflow)
• information available from and about local authorities relating to current and future developments that may affect population change
• the latest migration assumptions from the National Ethnic Population Projections: 2013(base)–2038 and Subnational Population Projections: 2013(base)–2043.

Migration assumptions at the subnational level generally reflect the assumptions at the national level. 'European or Other', Māori, and Asian net migration is assumed to be higher during 2014–18 than subsequent periods. For 2019–38, the migration assumptions reflect average annual net migration over that period, although annual net migration can be expected to vary from year to year.

The low and high net migration assumptions represent plausible alternative migration scenarios for each area and each ethnic group. They therefore do not sum to any specific national total.

Inter-ethnic mobility

Inter-ethnic mobility (IEM) assumptions are applied to each age-sex group to allow for the net effect of people changing their ethnic identification over time. The IEM assumptions are the same as used in the [National Ethnic Population Projections: 2013(base)–2038](https://datainfoplus.stats.govt.nz/item/nz.govt.stats/50fa98a5-8f92-463c-a633-5866ea2c0988. Under the national median assumption, there is an average net change to the population in 2014–38 due to people changing their ethnic identification for:

• 'European or Other' of 0.04 percent a year
• Māori of 0.43 percent a year
• Asian of -0.08 percent a year
• Pacific of -0.11 percent a year.

Because age-specific rates are applied, the overall net IEM changes over time and will vary between areas.

The low and high net IEM assumptions are chosen to represent plausible alternative IEM scenarios for each area and each ethnic group.

Which projection should I use?

Three alternative projections (designated low, medium, and high growth) were produced for each area and each ethnic group using different fertility (and paternity), mortality, migration, and inter-ethnic mobility assumptions. Users can make their own judgment as to which projections are most suitable for their purposes. At the time of release, the medium projection is considered suitable for assessing future population change and is consistent with the median projection (50th percentile) of the National Ethnic Population Projections: 2013(base)–2038 (released 21 May 2015) and the medium projection of the Subnational Population Projections: 2013(base)–2043 (released 19 February 2015). Other percentiles or projections cannot be directly compared because the projection assumptions may be incompatible.

The low and high projections allow users to assess the impact on population size and structure resulting from lower growth and higher growth scenarios, respectively. The low projection uses low fertility, low paternity, high mortality, low net migration, and low net inter-ethnic mobility for each area and each ethnic group. The high projection uses high fertility, high paternity, low mortality, high net migration, and high net inter-ethnic mobility for each area and each ethnic group. The low and high projections are independent of the national ethnic population projections and subnational population projections as they represent plausible alternative scenarios for each area.