This section contains information about data that has changed since the last release.
This section has information that does not change between releases.
Changes in release schedule
In order to provide additional information about population change following the 2010/11 Canterbury earthquakes, subnational population estimates by age (previously released in mid-December each year) have been included in this release. Population estimates for urban areas (previously released in late October each year) will now be released on 19 December 2011, in conjunction with population estimates for area units.
Effect of the 2010/11 Canterbury earthquakes on data accuracy
Population estimates give the best available measure of the size and age-sex structure of the population usually living in an area. However, uncertainty is inherent in the estimation process. Statistics NZ produces subnational population estimates using a component methodology, where the components of population change (births, deaths, and net migration) are used to update a base population. There is some uncertainty associated with component data, particularly the estimation of net migration (international and internal migration combined) for subnational areas. Generally speaking, the uncertainty associated with population estimates increases as the estimates move further away from the base (starting point). Uncertainty also increases as population estimates are broken down by age, sex, and geographic area.
An evaluation of subnational population estimates produced during the 2002–06 period identified that, five years out from the 2001 base population, absolute relative errors were less than 5 percent for 60 out of 73 territorial authority areas. For the ten territorial authority areas with a population greater than 100,000, relative errors ranged from an underestimate of -2.2 percent (Manukau city) to an overestimate of 0.5 percent (Auckland city).
The 2010/11 Canterbury earthquakes triggered large migration flows as people were displaced from earthquake-affected areas. Consequently, some additional uncertainties apply to the subnational population estimates at 30 June 2011. These uncertainties concern whether population movements:
- are short-term (ie temporary) or long-term in nature
- occurred before or after the 30 June 2011 reference date.
It is not possible to ascertain the accuracy of current population estimates as no independent authoritative measure of the resident population exists. Since 2006, Statistics NZ has implemented a number of changes to its estimation methods aimed at improving the accuracy of population estimates. This has included the use of new data sources and refined methods for using existing data sources. The data sources that have been used to produce subnational population estimates at 30 June 2011 are outlined in Estimating local populations after the 2010/11 Canterbury earthquakes.
In reality, there is no data source that perfectly measures the resident population of New Zealand or of subnational areas. Furthermore, there is no data source that perfectly measures changes in the resident population, or even movements of the resident population within New Zealand. With regards to Christchurch city, the data sources yield different measures of population change for the June 2011 year. However, collectively the different data sources provide confidence about the general robustness of population estimates.
Announcements on 'red zoning' in Christchurch city and Waimakariri district – land areas to be removed from residential use – were first made in June 2011. It is anticipated that most of the population movement out of these areas will occur in the June 2012 and 2013 years. Statistics NZ will continue to assess multiple data sources to ensure that future population estimates are as accurate as possible.
The periodic Census of Population and Dwellings remains the cornerstone of population statistics in New Zealand. Following the 2013 Census it will be possible to derive updated estimates of the population, to assess the accuracy of estimates since 2006, and to revise estimates where necessary.
Provisional and final estimates
The population estimates contained in this release are provisional. They incorporate provisional estimates of births, deaths, and migration that occurred in the June 2011 year. Final estimates will be released later in 2011 (see the Related links section for release dates). In addition, all population estimates after 30 June 2006 will be revised following results from the 2013 Census of Population and Dwellings.
The population estimates in this release are based on boundaries at 1 July 2011. They take into account recent boundary changes involving Kawerau and Whakatane districts (which came into effect on 9 March 2011), and Waikato district and Hamilton city (which came into effect on 1 July 2011).
The estimated resident population at 30 June 2006 forms the base population for deriving post-censal population estimates.
The estimated resident population of each area at 30 June 2006 is based on the census usually resident population count from the 2006 Census (held on 7 March 2006), with adjustments for:
- people missed or counted more than once by the census (net census undercount)
- residents temporarily overseas on census night
- births, deaths, and net migration between census night and 30 June 2006
- reconciliation with demographic estimates at ages 0–4 years.
Deriving subnational population estimates
Subnational population estimates for dates after 30 June 2006 were derived by updating the estimated resident population of each area at 30 June 2006 for births, deaths, and net migration (international and internal migration combined).
Birth and death registrations are used to estimate the number of births and deaths that occurred during each June year. There is often a delay between when a birth or death occurs and when it is registered, and this delay is taken into account when estimating birth and death occurrences.
Multiple data sources are traditionally used to derive estimates of subnational migration. These include:
- international (permanent and long-term) migration statistics
- symptomatic indicators of population change (including residential building consents, electoral enrolments, and school enrolments)
- information provided by territorial authorities during an annual consultation round.
Additional data sources were also used to estimate subnational populations at 30 June 2011. Information on these data sources is contained in Estimating local populations after the 2010/11 Canterbury earthquakes.
Subnational population estimates are consistent with national population estimates for a given reference date.
2006-base population estimates extended
Statistics NZ planned to produce 2006-base post-censal estimates until mid-2012. Following the cancellation of the 2011 Census of Population and Dwellings, 2006-base post-censal estimates will now be produced until mid-2014.
2013-base population estimates
The 2013 Census of Population and Dwellings will take place on Tuesday 5 March 2013. The 2013 Census website (www.census.govt.nz) provides information about the census.
Population estimates based on the 2013 Census will be released from August 2014.
All figures in this release were rounded independently.
The rounding of estimates of the total population, and broad age groups, has been determined by the total population size of the geographic area. Estimates for areas with a population less than 10,000 are rounded to the nearest 10. For areas with a population between 10,000 and 20,000, estimates are rounded to the nearest 50. Estimates for areas with a population of 20,000 or more are rounded to the nearest 100.
The rounding of estimates of natural increase, net migration, and population change has been determined by the absolute value of the estimate. Estimates less than 1,000 have been rounded to the nearest 10. Estimates greater than 1,000 have been rounded to the nearest 100.
All derived figures in this release were calculated using data of greater precision than published.
Information about the population estimates contains detailed information about the methods used to derive population estimates.
While all care and diligence has been used in processing, analysing, and extracting data and information in this publication, Statistics NZ gives no warranty it is error-free and will not be liable for any loss or damage suffered by the use directly, or indirectly, of the information in this publication.
Timing of published data
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 NZ. Statistics NZ accepts no responsibility for any such delays.
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