Latest projections
This release contains 2004-base projections of the population usually living in New Zealand. The projections supersede the 2001-base series released in October 2002. The new projections cover the period 2005–2051 at one-year intervals.
Base population
These projections have as a base the estimated resident population of New Zealand at 30 June 2004. This population (4.061 million) was derived from the estimated resident population of New Zealand at 30 June 2001 (3.880 million), updated for births, deaths and net migration between 30 June 2001 and 30 June 2004 (+181,000). The estimated resident population of New Zealand at 30 June 2001 was based on the census usually resident population count (3.737 million) at 6 March 2001, with adjustments for:
- net census undercount (+81,000)
- residents temporarily overseas on census night (+55,000)
- births, deaths and net migration between census night (6 March 2001) and 30 June 2001 (+4,000)
- reconciliation with demographic estimates at ages 0–9 years (+4,000).
For information about the base population, refer to Information About the Population Estimates on the Statistics New Zealand website (www.stats.govt.nz).
Alternative series
Nine alternative series have been produced using different combinations of fertility, mortality and migration assumptions. At the time of release, projection series 5 is considered the most suitable for assessing future population changes. The other projection series allow users to assess the impact on population size and structure resulting from changes in the assumptions for each of the components of population change. Series 4, 5 and 6 can be used for assessing the effect of the different migration assumptions; series 3, 5 and 7 allow for a comparative mortality analysis; and series 2, 5 and 8 allow for a comparative fertility analysis.
Series 1 and 9 give the lowest and highest projected population, respectively, based on the adopted assumptions. Series 1 uses low fertility, high mortality and low net migration. Series 9 uses high fertility, low mortality and high net migration.
Five additional series have also been produced to illustrate how the population will change if certain demographic events were to occur:
- The total fertility rate increases linearly to 2.5 births per woman in 2016 and then remains constant.
- Life expectancy at birth increases linearly to 91.3 years for males and 92.9 years for females in 2051.
- No migration at any age throughout the projection period.
- Annual net migration fluctuates between -10,000 and 30,000 over a 10-year cycle, with an average of 10,000.
- Annual net migration of 25,000 throughout the projection period.
More detailed projection results, including projections for individual years or projections by age and sex, are available from the Statistics New Zealand website or on request. Special projections can also be produced for clients using their own assumptions. For more information and quotes, email demography@stats.govt.nz or phone toll-free 0508 525 525.
Method
The cohort component method was used to derive the population projections. By this method, the base population is projected forward by calculating the effects of deaths and migration within each age-sex group according to specified mortality and migration assumptions. New birth cohorts are generated by applying specified fertility assumptions to the female population of childbearing age.
Projection assumptions
Projection assumptions are formulated after analysis of short- and long-term historical trends, recent trends and patterns observed in other countries, government policy, and any other relevant information.
Fertility
There are three alternative fertility variants – designated low, medium and high – which assume that fertility rates will vary until the year 2016 when the total fertility rate will reach 1.60, 1.85 and 2.10 births per woman, respectively. After 2016, fertility rates are assumed to stay constant. The base total fertility rate in 2004 was 2.01 births per woman (based on births by date of registration).
The medium fertility variant assumes fertility rates of women aged under 32 years will decline between 2004 and 2016, while rates for women aged 32 years and over will increase slightly. By comparison, the low fertility variant assumes fertility rates will decrease between 2004 and 2016 for most ages. The high fertility variant assumes that fertility rates will drop between 2004 and 2016 for women aged under 28 years and increase for women aged 28 years and over.
A sex ratio at birth of 105.5 males per 100 females is assumed, based on the historical annual average.
Mortality
There are three alternative mortality variants – designated low, medium and high – which assume that mortality rates will continue to drop so that life expectancy at birth will increase to 86.0, 83.5 and 81.0 years for males, respectively, by 2051. The corresponding life expectancies for females in 2051 will be 89.0, 87.0 and 85.0 years. The base life expectancy at birth in 2004 was 77.0 years for males and 81.6 years for females.
Mortality rates are assumed to decrease at the same rate at all ages. Between 2004 and 2051, male mortality rates are assumed to decrease by about 55, 44 and 30 percent for the low, medium and high mortality variants, respectively. By comparison, female mortality rates are assumed to decrease by about 51, 40 and 28 percent for the low, medium and high mortality variants, respectively.
Migration
There are three alternative migration variants – designated low, medium and high – which assume long-term annual net migration levels of 5,000, 10,000 and 15,000, respectively. Short-term migration levels converging to the long-term levels are assumed for 2005–2008. These short-term levels are based on an analysis of immigration permits, residence applications and approvals, overseas student numbers, and arrivals and departures analysed by characteristics such as citizenship, country of last/next permanent residence and age.
Note: PLT – permanent and long-term (12 months or more) migration. Total – total migration, which includes the short-term (less than 12 months) movement of overseas and New Zealand residents, as well as permanent and long-term migration.
Consistent with historical and recent trends, the age-sex patterns of net migration assume the main net outflow at ages 21–26 years, mainly due to young New Zealanders embarking on overseas travel and the departure of students from overseas after studying in New Zealand. Net inflows are assumed for most other ages, with the highest net inflows at 0–19 and 28–50 years.
Nature of projections
Demographic projections are designed to meet both short-term and long-term planning needs, but are not designed to be exact forecasts or to project specific annual variation. These projections are based on assumptions made about future fertility, mortality, and net migration patterns of the population. Although the assumptions are carefully formulated to represent future trends, they are subject to uncertainty. Therefore, the projections should be used as guidelines and an indication of the overall trend, rather than as exact forecasts.
The projections do not take into account non-demographic factors (eg war, catastrophes, major government and business decisions) which may invalidate the projections. Demographic trends are monitored regularly and, when it is necessary, the projections are revised to reflect new trends and to maintain their relevance and usefulness.
For more information about the projections, refer to Information About the Demographic Projections on the Statistics New Zealand website (www.stats.govt.nz).
Definitions
A baby boomer is usually someone born in the years 1946–1965, although the definition of the baby boom period varies between sources and between countries.
The de facto population concept is a statistical basis for a population in terms of those present in a given area at a given time. The census night population count is a census measure of the de facto population concept, and the estimated de facto population is a demographic measure of the de facto population concept.
The estimated resident population of New Zealand is an estimate of all people who usually live in New Zealand at a given date. It includes all residents present in New Zealand and counted by the census (census usually resident population count), residents who are temporarily overseas (who are not included in the census), and an adjustment for residents missed or counted more than once by the census (net census undercount). Visitors from overseas are excluded.
Life expectancy is the average length of life remaining at a given age. As derived from a period life table, it assumes that a person experiences the age-specific mortality rates of a given period from the given age onwards. It represents the average longevity of the whole population and does not necessarily reflect the longevity of an individual.
Replacement fertility generally refers to a total fertility rate of 2.1 children per woman, which equates to the average number of children each woman is required to have for a population to replace itself in the long term, without migration. The rate allows for the sex ratio at birth (roughly 105 males born for every 100 females) and for some mortality of females between birth and childbearing.
The resident population concept is a statistical basis for a population in terms of those who usually live in a given area at a given time. The census usually resident population count is a census measure of the resident population concept, and the estimated resident population is a demographic measure of the resident population concept. In terms of vital statistics, the resident population concept refers to events that relate to residents of New Zealand only.
The total fertility rate is the average number of live births that a woman would have during her life if she experienced the age-specific fertility rates of a given period (usually a year).
Copyright
Information obtained from Statistics New Zealand may be freely used, reproduced, or quoted unless otherwise specified. In all cases Statistics New Zealand must be acknowledged as the source.
Liability
While care has been used in processing, analysing and extracting information, Statistics New Zealand gives no warranty that the information supplied is free from error. Statistics New Zealand shall not be liable for any loss suffered through the use, directly or indirectly, of any information, product or service.
Timing
Timed statistical releases are delivered using postal and electronic services provided by third parties. Delivery of these releases may be delayed by circumstances outside the control of Statistics New Zealand. Statistics New Zealand accepts no responsibility for any such delays.
Next release ...
Subnational Population Projections: 2001(base)–2021 update
will be released on 28 February 2005.