Subnational Population Projections 2013-base

Period-specific information Reference period This release contains 2013-base projections of the population usually living in the 16 regional council areas (regions), 67 territorial authority areas (cities and districts), and 21 Auckland local board areas of New Zealand. These supersede the 2006-base projections released in October 2012. The new projections incorporate the latest demographic information, including: National Population Projections: 2014(base)–2068 (released 28 November 2014) subnational population estimates birth and death registrations international travel and migration data. The new projections have the estimated resident population at 30 June 2013 as a base, and cover the period to 2043 at five-year intervals. Changes since the previous 2006-base projections Review of assumptions The derivation of the projections involves a review of all projection assumptions for each area. The changes from the previous 2006-base projections (October 2012 update) mainly relate to the base population and short-term migration assumptions. The new 2013-base population estimates incorporate results from the 2013 Census of Population and Dwellings and 2013 Post-enumeration Survey. The median annual net migration gain is assumed to be 12,000 in the long term, the same as the 2011-base projections. The 2014-base projections have a short term migration gain equating to 149,300 for the 5 years ended 2018 and 60,000 for each subsequent 5-year period. The median projection of the New Zealand population from the 2014-base projections is 4.95 million in 2023 and 5.64 million in 2043. By comparison, the equivalent populations from the previous 2011-base projections were 4.88 million in 2023 and 5.57 million in 2043. 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 2014. Projection assumptions Projection assumptions are formulated after analysis of short-term and long-term historical trends, information provided by local planners, and government policy. The Subnational population projections, projection assumptions, 2013(base)–2043 table in NZ.Stat provides a summary of the low, medium, and high projection assumptions for each area. 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 with adjustments 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 the registered births for each area during the period 2009–13, with change between 2013 and 2043 consistent with the fertility assumptions from the National Population Projections: 2014(base)–2068. Historical total fertility rates for subnational areas are not derived using conventional fertility methods but are merely modelled on the total number of registered live births for each area. These modelled total fertility rates should not be used as a precise measure of subnational fertility or of fertility differentials between areas. It is important to note that the objective of population projections is not to specifically measure or project the fertility of the population. For projection purposes it is more important to have a realistic yet tractable model for projecting birth numbers into the future. Under the medium fertility assumption, the period total fertility rate at the national level is assumed to decline gradually from 1.95 births per woman in 2015 to 1.92 in 2023 and 1.90 from 2030. In 2014–18 the medium fertility assumption ranges from 1.38 births per woman for Wellington city to 2.90 for Opotiki district. In 2039–43 the assumed total fertility rates range from 1.34 births per woman for Wellington city (low fertility assumption) to 3.01 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 registered deaths for each area during the period 2009–13, with change between 2013 and 2043 consistent with the mortality assumptions from the National Population Projections: 2014(base)–2068. Historical life expectancies at birth for subnational areas are not derived using conventional life table methods but are merely modelled on the total number of registered deaths for each area. These modelled life expectancies at birth should not be used as a precise measure of subnational mortality or of mortality differentials between areas. It is important to note that the objective of population projections is not to specifically measure or project the life expectancy of the population. For projection purposes it is more important to have a realistic yet tractable model for projecting death numbers into the future. Under the medium mortality assumption, period life expectancy at birth at the national level is assumed to increase from 80.2 years for males and 83.9 years for females in 2015 to 85.5 years for males and 88.7 years for females in 2043. In 2014–18 the medium mortality assumption ranges from 75.6 years for males and 79.5 years for females for Kawerau district, to 84.8 years for males and 88.4 years for females for Queenstown-Lakes district. In 2039–43 the assumed life expectancy at birth ranges from 79.0 years for males and 82.6 years for females for Kawerau district (high mortality assumption) to 90.8 years for males and 93.7 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 a consideration of observed net migration during each intercensal period from 1981 to 2013, 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 which may affect population change. Under the medium migration assumption, net migration at the national level is assumed to be 149,300 in 2014–18, and 60,000 in each subsequent five-year period. Of the 67 territorial authorities, only 14 are assumed to have the same net migration level in each five-year period between 2013 and 2043. The remaining areas 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 have attracted 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 1981–2013, subnational population estimates since 2013, and the latest migration assumptions from the National Population Projections: 2014(base)–2068. en-NZ