Subnational Population Projections 2013-base Update

Main changes since the previous 2013-base projections

Deriving the projections involved a review of all projection assumptions for each area, as well as being consistent with the latest national population projections. The main changes from the previous 2013-base projections (February 2015) relate to migration and fertility assumptions.

The 2016-base New Zealand population projections assumed higher levels of net migration and lower fertility rates than the previous 2014-base projections.

The median net migration gain is assumed to be 276,700 for 2014–18, 129,000 for 2019–23, and 75,000 for each subsequent five-year period. This compares with 149,300 for 2014–18 and 60,000 for each subsequent five-year period from the previous 2013-base projections.

The period total fertility rate decreased from 1.99 in 2014 to 1.90 in 2016. In 2043, it is assumed to decline to 1.85, compared with 1.90 in the previous 2014-base projections.

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 2017.

Base population

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

For more information about the base population, refer to Demographic Estimates. Fertility

The assumed fertility rates are based on estimated births for each area during the period 2013–16, with change between 2017 and 2043 being consistent with the fertility assumptions from the National Population Projections: 2016(base)–2068. Under the medium fertility assumption, the period total fertility rate at the national level is assumed to decline gradually, from 1.90 births per woman in 2016, to 1.87 in 2025, and 1.85 from 2036. In 2014–18 the medium fertility assumption ranges from 1.30 births per woman for Wellington city to 3.00 for Opotiki district. In 2039–43 the assumed total fertility rates range from 1.23 births per woman for Wellington city (low fertility assumption) to 3.15 births per woman for Opotiki district (high fertility assumption). A sex ratio at birth of 105.5 males per 100 females is assumed, based on the historical annual average at the national level. Mortality The assumed mortality rates are based on estimated deaths for each area during the period 2013–16, with change between 2017 and 2043 being consistent with the mortality assumptions from the National Population Projections: 2016(base)–2068.

Under the medium mortality assumption, period life expectancy at birth at the national level is assumed to increase from 80.6 years for males and 84.0 years for females in 2017, to 85.6 years for males and 88.5 years for females in 2043. In 2014–18 the medium mortality assumption ranges from 76.2 years for males and 79.7 years for females for Opotiki district, to 84.8 years for males and 88.1 years for females for Queenstown-Lakes district. In 2039–43 the assumed life expectancy at birth ranges from 79.7 years for males and 83.0 years for females for Opotiki district (high mortality assumption), to 90.9 years for males and 93.5 years for females for Queenstown-Lakes district (low mortality assumption). Migration 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. The assumed net migration for each area is based on considering observed net migration during each intercensal period from 1996 to 2013, estimated net migration from 2013 to 2016, the capacity of the area for further growth (for areas with net inflow), whether historical outflows can be sustained (for areas with net outflow), the desirability of the area to new migrants, and information available from and about local authorities relating to current and future developments that may affect population change.

Under the medium migration assumption, net migration at the national level is assumed to be 60,000 in 2017, and decrease by 9,000 annually to reach 15,000 in 2022 and beyond. All TA areas except for Chatham Islands territory and Kaikoura district are assumed to have different net migration levels during at least one of the five-year periods. Different levels are generally assumed for areas susceptible to changes in external migration, such as university cities (which attract large numbers of overseas students in some years), and areas where constant net outflows are considered unsustainable. The low and high net migration assumptions are chosen to represent plausible alternative migration scenarios for each area. The age-sex patterns of net migration for each area are based on observed intercensal net migration patterns during 1996–2013, subnational population estimates since 2013, and the latest migration assumptions from the National Population Projections: 2016(base)–2068.