QUALITY DECLARATION - SUMMARY
Preparation of estimated resident population (ERP) for areas within states and territories ('sub-state') uses data sourced from a variety of institutional environments. Much of this is administrative by-product data collected by other official organisations for purposes other than estimating the population.
Births and deaths statistics are sourced from registration systems administered by the various State and Territory Registries of Births, Deaths and Marriages. It is a legal requirement of each state and territory that all births and deaths are registered. Information about births is provided by the parent(s) of the child, while information about the deceased is provided by a relative or other person acquainted with the deceased, or by an official of the institution where the death occurred.
Estimates of net internal migration are calculated using administrative data on changes of address from Medicare records and the Department of Defence in the case of the military. Medicare change of address data is provided to the ABS by the Australian Government Department of Human Services. Medicare is Australia's universal health insurance scheme covering the large majority of Australians.
ABS Census of Population and Housing and Post Enumeration Survey (PES) data are used to determine a base population from which ERP is calculated. Census information is also used to estimate sub-state overseas migration. For information on the institutional environment of the Australian Bureau of Statistics (ABS), please see ABS Institutional Environment.
In non-Census years, the total population for each area is prepared first, and then broken down into its age and sex components using the administrative data as described above.
Sub-state ERP is calculated to add to the independently and previously derived state and territory population estimates. For information on the data used to calculate state and territory ERP, see the Explanatory Notes of Australian Demographic Statistics (cat. no. 3101.0).
ERP is the official measure of the population of areas in Australia according to a usual residence population concept. It refers to all people, regardless of nationality or citizenship, who usually live in Australia, with the exception of foreign diplomatic personnel and their families. It includes usual residents who are overseas for less than 12 months out of a continuous 16-month period. It excludes those who are in Australia for less than 12 months out of a continuous 16-month period.
Sub-state estimates of the resident population as at 30 June are released annually for all Statistical Areas Level 2 (SA2s) and Local Government Areas (LGAs) in Australia. They are also available for other statistical areas as defined in the Australian Statistical Geography Standard (ASGS), such as Greater Capital City Statistical Areas (GCCSAs), Significant Urban Areas (SUAs) and Remoteness Areas (RAs), and non-standard areas such as Commonwealth and State Electoral Divisions.
There are legislative requirements for the ABS to provide population estimates. ERP plays an important part in the allocation of federal government funding to the local government authorities of Australia. ERP for all statistical areas also assists in decisions regarding development, infrastructure (such as hospitals or schools) and policy formulation, monitoring and reporting. The geographic distribution of ERP informs on issues such as remoteness (access to services) and population density. The level and growth of ERP for each area over time both reflects and affects economic, social and environmental issues. In addition, the age/sex composition of ERP informs discussion of issues such as population health, ageing and fertility.
Sub-state ERP is released annually with a reference date of 30 June each year. To meet the competing demands for accuracy and timeliness there are several versions of these estimates. Preliminary estimates of sub-state population totals are available approximately nine months after the reference date and age-sex breakdowns are available about 13 months after the reference date. Revised estimates are available a year later (once revisions to births, deaths and net overseas migration at the state/territory level have been taken into account) and final estimates after the following Census.
All ERP data sources are subject to non-sampling error. Non-sampling error can arise from inaccuracies in collecting, recording and processing data. In the case of Census and PES data, every effort is made to minimise reporting error by the careful design of questionnaires, intensive training and supervision of interviewers, and efficient data processing procedures. The ABS does not have control over any non-sampling error associated with births and deaths data (managed by State and Territory Registries of Births, Deaths and Marriages) and Medicare data used for internal migration estimates (managed by the Department of Human Services). The accuracy of Medicare data is largely dependant on the length of time taken by people who move to update their address details with the relevant government agency.
Accuracy of sub-state ERP can be measured in Census years, when both preliminary estimates (derived from updating ERP from the previous Census) and final estimates (based on the current Census) are prepared. Differences between these two sets of estimates are referred to as intercensal differences. An indication of the accuracy of ERP can be gauged by assessing the size and direction of these differences. For further information regarding intercensal differences, see the Explanatory Notes of Regional Population Growth (cat. no. 3218.0).
The balance between timeliness and accuracy means that the user can choose more timely data (preliminary) or more accurate data (as revised or final data become available) depending on their needs.
The accuracy of sub-state ERP is partly dependent on the accuracy of state and territory population estimates, to which it is constrained. The accuracy of state and territory ERP is described in the Quality Declaration for Australian Demographic Statistics (cat. no. 3101.0).
In recognition of the inherent difficulty in population estimation, population figures in commentary text published by the ABS are rounded. While unrounded figures are provided in summary tables and the detailed spreadsheets, accuracy to the last digit should not be assumed. Estimates of change in population are based on unrounded numbers.
Population estimates are prepared based on the Australian Statistical Geography Standard (ASGS). Estimates are released for Statistical Areas Levels 2 to 4 (SA2s to SA4s) and Greater Capital City Statistical Areas (GCCSAs), as well as other ABS and Non-ABS Structures, including Local Government Areas (LGAs). For more information on the geographic regions of the ASGS see Australian Statistical Geography Standard (ASGS): Volume 1 - Main Structure and Greater Capital City Statistical Areas, July 2016 (cat. no. 1270.0.55.001).
Annual population estimates for LGAs and/or other sub-state regions have been published (not necessarily by the Australian Bureau of Statistics) for Victoria since 1875, New South Wales and Queensland since 1911, South Australia since 1915, Tasmania since 1923, Western Australia since 1926, the Australian Capital Territory since 1968 and the Northern Territory since 1981.
Population estimates based on the concept of 'usual residence' have been produced for sub-state regions since the 1970s. Prior to this, sub-state population figures were calculated on the 'actual location' concept - that is, based on the number of persons actually present at that location at the given time. Estimates based on actual location are generally higher in areas which attract short-term migrants, such as tourist areas, and it is important to note this break in time series when comparing historical population estimates.
Prior to 30 June 2017 estimates, intercensal sub-state ERP was prepared using a regression model, whereby change in population was modelled based on changes in indicator data sources (dwelling approvals, Medicare enrolment counts and counts of people on the Australian Electoral Roll). From 2017 onwards, estimates have been prepared using the component method, whereby ERP is prepared by adding natural increase (births minus deaths) and net migration occurring over a period to the population at the beginning of the period . While this is a significant change in the method used to estimate population change out from Census-based estimates, it is not considered a break in time series. The method used to estimate intercensal ERP shapes rebased intercensal population change, however the end points reflect what the previous and most-recent Censuses have shown for each area. Under the old regression method, new models were prepared every five years based on what was learnt from the last two Censuses. Therefore, under a regression- or component-based approach, the estimation process is reset every five years.
The sub-state births and deaths data in this publication are not coherent with the sub-state data found in ABS births and deaths publications, which is presented according to calendar years and has a different scope. The births and deaths data contained in this publication are for financial years, to correspond with the 30 June reference date for ERP.
ERP is generally easy to interpret as the official measure of Australia's population on a place of usual residence basis. However, there are still some common misconceptions. For example, a population estimate uses the term 'estimate' in a different sense than is commonly used. Generally the word estimate is used to describe a guess or approximation. Demographers mean that they apply the demographic balancing equation by adding births, subtracting deaths and adding the net of overseas and internal migration to a base population. Each of the components of sub-state ERP is subject to error, but ERP itself is not in any way a guess. It is what the population would be if the components are measured well. More detailed explanations of the concept of ERP, as adopted by the ABS for official population estimates, are contained in Information Paper: Population Concepts (cat. no. 3107.0.55.006) and Population Estimates: Concepts, Sources and Methods (cat. no. 3228.0.55.001).
In text and data published by the ABS, areas are ranked according to ‘largest’ and ‘fastest’ growth in ERP. Largest growth is based on the absolute change in population between 30 June of the base year and 30 June of the reference year, while fastest growth is based on the rate of change (percentage change) in population for the same period. Areas with ERP of less than 1,000 people in the base year are excluded from the fastest growth rankings due to the volatility of percentage changes when calculations are based on small numbers. Due to the volatility of small-area population estimates, rankings should be considered indicative of relative growth between areas within each state and territory, not definitive.
Annual population estimates at 30 June for all SA2s and LGAs in Australia are made freely available on the ABS web site in a variety of formats via the Downloads tab of this product. Key figures are also presented in the main features and state and territory commentaries accompanying this release. A list of related ABS releases that may be of interest to users of these estimates can be found in the Explanatory Notes.
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