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Regional Population by Age and Sex, Australia methodology

Reference period
2018
Released
29/08/2019

Explanatory notes

Introduction

1 This release contains estimates of the resident population of Statistical Areas Levels 2 to 4 (SA2s - SA4s) and Greater Capital City Statistical Areas (GCCSAs) of Australia as at 30 June 2001 to 30 June 2018, by age and sex. These estimates plus those for Local Government Areas are provided in the Data downloads section of this issue.

2 To meet the competing demands for accuracy and timeliness, there are several versions of sub-state population estimates. Preliminary estimates by age and sex as at 30 June are normally available by August of the following year, revised estimates 12 months later and rebased and final estimates after the following Census. The estimates in this issue are final for 2001 to 2016, revised for 2017, and preliminary for 2018.

3 The estimates in this issue are consistent with the total sub-state estimates released in the 2017-18 issue of Regional Population Growth, Australia (cat. no. 3218.0) on 27 March 2019 and the state/territory estimates by age and sex released in the September 2018 issue of Australian Demographic Statistics (cat. no. 3101.0). Subsequent updates to state/territory population estimates will be incorporated in future issues of Regional Population by Age and Sex, Australia (cat. no. 3235.0).

Estimated resident population

4 Estimated resident population (ERP) is the official estimate of the Australian population, which links people to a place of usual residence within Australia. Usual residence within Australia refers to that address at which the person has lived or intends to live for six months or more in a given reference year. For the 30 June reference date, this refers to the calendar year around it. More detailed explanations of the concept of ERP, as adopted by the ABS for official population estimates, are contained in Population Estimates: Concepts, Sources and Methods (cat. no. 3228.0.55.001).

5 Estimated resident population is based on Census counts by place of usual residence (excluding short-term overseas visitors in Australia), with an allowance for Census net undercount, to which are added the estimated number of Australian residents temporarily overseas at the time of the Census.

Australia, states and territories

6 Population estimates for Australia and the states and territories (from now on referred to as states) are updated by adding to the estimated population at the beginning of each period the components of natural increase (births minus deaths, on a usual residence basis) and net overseas migration. For state populations, interstate migration is also accounted for.

Statistical Area Level 2 (SA2)

7 In Australia, the SA2 (as defined in the Australian Statistical Geography Standard (ASGS)) is the base spatial unit used to collect and disseminate statistics other than those collected from the Census. In aggregate, SA2s cover the whole of Australia without gaps or overlaps. Populations for SA2s are estimated as at 30 June each year. Population estimates for larger regions are built up from SA2-level estimates.

8 The ERP as at Census date for each SA2 is calculated based on usual residence Census counts, excluding short-term overseas visitors in Australia, with an allowance for Census net undercount and the number of residents temporarily overseas (RTOs) at the Census date. The estimates of net undercount are apportioned to SA2s based on age, sex, Indigenous status, state and territory, and broad region. The number of RTOs on Census night is estimated based on coding addresses of residence to SA2 from a sample of incoming passenger cards provided by the Department of Home Affairs. As the Census is not held on 30 June (the 2016 Census was held on 9 August), further adjustments to account for births, deaths and migration for the intervening period are made to obtain the ERP at 30 June. A procedure is then applied to avoid the release of unconfidentialised usual residence Census counts while maintaining consistency with the unconfidentialised ERP.

9 SA2 populations are updated in post-Census years (from 2016) by adding to the estimated population at the beginning of each period the components of natural increase (births minus deaths), net internal migration (moves between and within the states) and net overseas migration. This method and its data sources are explained in Feature Article: New Methodology Used to Prepare Sub-state Population Estimates. In some very small areas, population change since the previous Census may be assumed to be zero in the absence of reliable component data for these areas. All estimates are scrutinised and validated by ABS analysts. Local knowledge, such as that advised by state governments (including peer reviewers) is considered and used to adjust the figures for particular SA2s. Estimates at the SA2 level are constrained so that they add to the relevant state population estimates.

10 Total population estimates for each SA2 for post-Census years are then broken down by age and sex by ageing the previous year's population by one year, and incorporating the components of population change - births (by sex), and deaths, internal and overseas migration (by age and sex). Further information on these components is contained in the Explanatory Notes of Regional Population Growth, Australia (cat. no. 3218.0). Prior to 2016, the internal and overseas migration components were based on migration profiles from the previous Census. For areas where the components are of insufficient quality, adjustments are made. These components are confidentialised and constrained to add to the relevant state component estimates by age and sex. The resultant ERPs are subsequently constrained to state population estimates by age and sex. As a result of confidentialisation and forced additivity, estimates of under three people should be regarded as synthetic and only exist to ensure additivity to higher levels. While output is presented by five-year age group (up to 80 to 84 years, then 85 years and over), all calculations are made at single year of age level (up to 99 years, then 100 years and over). Population estimates based on single year of age may be available on request as a charged consultancy.

11 While sub-state ERP by age and sex is consistent with state ERP by age and sex, differences arise between aggregated sub-state components by age and otherwise published state components by age. This is due to the different reference period of sub-state ERP (annual as at 30 June) and state ERP (quarterly), as the age of a person at the end of the financial year can be different to the age of that person at the end of each quarter.

12 In Census years, both preliminary estimates (derived from updating ERP from the previous Census) and rebased population estimates (based on the current Census) are prepared. Differences between these two sets of estimates are referred to as intercensal differences. Rebased estimates of SA2 populations for previous intercensal years are derived by apportioning the intercensal difference across the five years, while constraining to state estimates. Rebased 2012 to 2015 estimates were generally derived by adding one-fifth of the 2016 intercensal difference to the previous estimate of the 2012 population, two-fifths to the previous estimate of the 2013 population, and so on.

Statistical Area Level 1 (SA1) and SA1-based geographies

13 The SA1 is the smallest geographic unit for the release of Census data. There are approximately 57,500 SA1s and they cover the whole of Australia without gaps or overlaps. To provide some indication of ERP below the SA2 level, the ABS prepares population estimates for SA1s, which are then aggregated to regions such as Remoteness Areas and electoral divisions. By this means, population estimates for areas other than those provided in this product (including SA1s) may be available on request as a charged consultancy.

14 Population estimates at the SA1 level as at 30 June of a Census year are compiled by apportioning the estimate for each SA2 across the SA1s within the SA2, using Census usual residence counts by age and sex. In intercensal years, total population estimates for SA2s are apportioned across SA1s by taking into account population change implied by Medicare enrolments and Australian Electoral Roll counts at the SA1 level in the years following the Census. These total SA1 populations are then broken down by age and sex by ageing the previous year's population, with age distributions for selected areas held static.

Local Government Area (LGA)

15 In Census years, LGA ERP by age and sex is aggregated from whole SA2 or SA1 level estimates by age and sex where possible. Where LGAs cross SA1 boundaries, Mesh Block Census counts are used to estimate the share of the SA1 population that reside in those LGAs. LGA population estimates are updated in intercensal years from 2016 by accounting for the components of population change. The resulting LGA ERP by age and sex is constrained to SA2 ERP by age and sex to ensure consistency between these two geographies, based on the smallest possible regions where SA2 and LGA boundaries match in terms of the combined area containing resident population. For example, where one LGA aligns exactly with one SA2 or where a group of LGAs aligns with a group of SA2s, the ERP for these areas will generally match.

16 To enable the comparison of regional populations over time, historical population estimates based on consistent updated geographic boundaries are prepared, for example when boundaries of Local Government Areas change. These estimates correspond with previously released estimates (on different boundaries) where possible.

Accuracy of sub-state population estimates

17 In recognition of the inherent difficulty involved in estimating population, population figures in text and accompanying summary tables published by the ABS are generally rounded. In the commentary for this product, figures less than 1,000 are rounded to the nearest ten, figures over 1,000 are rounded to the nearest hundred, and figures over 1 million are rounded to the nearest 10,000 or 100,000. While unrounded figures are provided in the spreadsheets, accuracy to the last digit should not be assumed. Percentages and estimates of change in population are based on unrounded numbers.

18 Areas with a total population of less than 1,000 people at 30 June 2018 have been excluded from commentary in this issue.

Australian statistical areas

19 This publication contains data presented according to the 2016 edition of the Australian Statistical Geography Standard (ASGS), which refers to boundaries as defined at 1 July 2016. Under this classification, statistical areas are defined as follows:

  • Statistical Areas Level 2 (SA2s). SA2s are medium-sized general purpose areas which aim to represent communities that interact together socially and economically. SA2s are based on officially gazetted suburbs and localities. In urban areas SA2s largely conform to one or more whole suburbs, while in rural areas they generally define the functional zone of a regional centre.
  • Statistical Areas Level 3 (SA3s). SA3s are aggregations of whole SA2s and reflect a combination of widely recognised informal regions as well as administrative regions such as state government regions in rural areas and Local Government Areas in urban areas.
  • Statistical Areas Level 4 (SA4s). SA4s are made up of whole SA3s and are designed to reflect labour markets. In rural areas, SA4s generally represent aggregations of small labour markets with socioeconomic connections or similar industry characteristics. Large regional city labour markets are generally defined by a single SA4. Within major metropolitan labour markets SA4s represent sub-labour markets.
  • Greater Capital City Statistical Areas (GCCSAs). GCCSAs are built from whole SA4s and represent a broad socioeconomic definition of each of the eight state and territory capital cities. They contain not only the urban area of the city, but also the surrounding and non-urban areas where much of the population has strong links to the capital city, through for example, commuting to work.
     

20 This product also contains data presented according to the 2018 edition of the Australian Statistical Geography Standard (ASGS) - Non ABS Structures.

  • Local Government Areas (LGAs). LGAs are ABS approximations of officially gazetted LGAs as defined by each state and territory local government department. LGAs cover incorporated areas of Australia, which are legally designated areas for which incorporated local governing bodies have responsibility. The ABS updates LGAs annually, and prepares updated and historical population estimates based on these updated boundaries.
     

21 Further information on these statistical areas is contained in:

Australian Statistical Geography Standard: Volume 1 - Main Structure and Greater Capital City Statistical Areas, July 2016 (cat. no. 1270.0.55.001)
Australian Statistical Geography Standard: Volume 3 - Non ABS Structures, July 2018 (cat. no. 1270.0.55.003)

22 Maps for Australian statistical areas are available in the online mapping tool ABS Maps. A complete series of SA2 maps is available to download from Australian Statistical Geography Standard: Volume 1 - Main Structure and Greater Capital City Statistical Areas, July 2016 (cat. no. 1270.0.55.001).

Population pyramid graphs

23 Population pyramids are used in this issue to illustrate the age and sex distribution of a population. In each case, five-year age groups are represented on the vertical axis of the graph. For pyramids showing percentage distribution in this product, the population in each age-sex group in an area is expressed as a percentage of the total population in that area. Thus, the sum of the percentages indicated by the bars of one colour in a population pyramid will be 100% of the population of the area represented by that colour, e.g. Greater Sydney. Further, the sum of the percentages indicated by the bars of the other colour will be 100% of the population of the area represented by the other colour, e.g. the rest of NSW. By using this method, the age and sex distribution of two areas can be compared irrespective of the relative sizes of the total populations of the areas.

Acknowledgement

24 ABS publications draw extensively on information provided freely by individuals, businesses, governments and other organisations. Their continued cooperation is very much appreciated; without it, the wide range of statistics published by the ABS would not be available. Information received by the ABS is treated in strict confidence as required by the Census and Statistics Act 1905.

Related releases

25 Other ABS releases that are freely available on the ABS website and may be of interest to users of this product include:

Australian Demographic Statistics (cat. no. 3101.0)

Regional Population Growth, Australia (cat. no. 3218.0)

Births, Australia (cat. no. 3301.0)

Deaths, Australia (cat. no. 3302.0)

Migration, Australia (cat. no. 3412.0)

Australian Historical Population Statistics (cat. no. 3105.0.65.001)

Population Projections, Australia (cat. no. 3222.0)

Information Paper: Population Concepts (cat. no. 3107.0.55.006)

Population Estimates: Concepts, Sources and Methods (cat. no. 3228.0.55.001)

Quality Assurance of Rebased Population Estimates, 2016 (cat. no. 3250.0.55.001)

Data by Region

Additional statistics available

26 The ABS may have other relevant data available on request. Inquiries should be made to the National Information and Referral Service on 1300 135 070. The ABS Privacy Policy outlines how the ABS will handle any personal information provided to us.

Glossary

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12/16 month rule

Under a '12/16 month rule', incoming overseas travellers (who are not currently counted in the population) must be resident in Australia for a total period of 12 months or more, during the 16 month follow-up period to then be added to the estimated resident population. Similarly, those travellers departing Australia (who are currently counted in the population) must be absent from Australia for a total of 12 months or more during the 16 month follow-up period to then be subtracted from the estimated resident population.

The 12/16 month rule does not have to be continuous and takes account of those persons who may have left Australia briefly and returned, while still being resident for 12 months out of 16. Similarly, it takes account of Australians who live most of the time overseas but periodically return to Australia for short periods.

Australian Statistical Geography Standard (ASGS)

The ASGS brings all the regions for which the ABS publishes statistics within the one framework and has been in use for the collection and dissemination of geographically classified statistics since 1 July 2011. It is the current framework for understanding and interpreting the geographical context of statistics published by the ABS.

Birth

The delivery of a child, irrespective of the duration of pregnancy, who, after being born, breathes or shows any other evidence of life such as heartbeat.

Capital city

Refers to the Greater Capital City Statistical Areas of states and territories as defined in the Australian Statistical Geography Standard.

Census

The complete enumeration of a population at a point in time with respect to well-defined characteristics (e.g. Persons, Manufacturing, etc.). When the word is capitalised, "Census" refers to the national Census of Population and Housing.

Death

Death is the permanent disappearance of all evidence of life after birth has taken place. The definition excludes deaths prior to live birth. For the purposes of death registration collections compiled by the ABS, a death refers to any death which occurs in, or en route to Australia and is registered with a state or territory Registry of Births, Deaths and Marriages.

Estimated resident population (ERP)

The official measure of the population of Australia, based on the concept of usual residence. It refers to all people, regardless of nationality, citizenship or legal status, 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 over a 16-month period. It excludes overseas visitors who are in Australia for less than 12 months over a 16-month period. Sub-state estimates of the resident population are prepared on an annual basis by adding natural increase (the excess of births over deaths), net internal migration and net overseas migration occurring during the period to the population at the beginning of each period.

Greater Capital City Statistical Area (GCCSA)

Represent the socioeconomic area of each of the eight state and territory capital cities. These boundaries are built from aggregations of whole Statistical Areas Level 4. GCCSA boundaries represent a broad socioeconomic definition of each capital city, containing not only the urban area of the capital city, but also surrounding and non-urban areas where much of the population has strong links to the capital city, through for example, commuting to work.

Intercensal difference

The difference between two estimates of a Census year population as at 30 June: the first based on the latest Census and the second produced by updating from the previous Census-based estimates which do not take account of information available from the latest Census.

Internal migration

The movement of people across a specified boundary within Australia involving a change in place of usual residence.

Interstate migration

The movement of people over a state or territory boundary involving a change in place of usual residence. Net interstate migration (NIM) is the difference between arrivals and departures and can be either positive or negative.

Local Government Area (LGA)

An ABS approximation of an officially gazetted LGA as defined by each state and territory local government department. LGAs cover incorporated areas of Australia, which are legally designated areas for which incorporated local governing bodies have responsibility. The major areas of Australia not administered by incorporated bodies are the northern parts of South Australia and all of the Australian Capital Territory and the Other Territories. These regions are identified as 'Unincorporated' in the LGA structure of the Australian Statistical Geography Standard.

Median age

For any distribution, the median value is that which divides the relevant population into two equal parts, half falling below the value, and half exceeding it. Thus, the median age is the age at which half the population is older and half is younger.

Mesh Block

The smallest geographic region in the Australian Statistical Geography Standard (ASGS) which forms the basis for all larger regions of the ASGS. They broadly identify land use such as residential, commercial, agricultural and parks. There are approximately 358,000 Mesh Blocks and they cover the whole of Australia without gaps or overlaps.

Natural increase

Excess of births over deaths.

Net overseas migration (NOM)

Net overseas migration is the net gain or loss of population through immigration to Australia and emigration from Australia. Under the current method for estimating final net overseas migration this term is based on a traveller's actual duration of stay or absence using the '12/16 month rule'. Preliminary NOM estimates are modelled on patterns of traveller behaviours observed in final NOM estimates for the same period one year earlier.

NOM arrivals

NOM arrivals are all overseas arrivals that contribute to net overseas migration (NOM). It is the number of incoming international travellers who stay in Australia for 12 months or more over a 16-month period, who are not currently counted within the population, and are then added to the population. Under the current method for estimating final net overseas migration this term is based on a traveller's actual duration of stay or absence using the '12/16 month rule'.

NOM departures

NOM departures are all overseas departures that contribute to net overseas migration (NOM). It is the number of outgoing international travellers who leave Australia for 12 months or more over a 16-month period, who are currently counted within the population, and are then subtracted from the population. Under the current method for estimating final net overseas migration this term is based on a traveller's actual duration of stay or absence using the '12/16 month rule'.The difference between the actual Census count (including imputations) and an estimate of the number of people who should have been counted in the Census. This estimate is based on the Post Enumeration Survey (PES) conducted after each Census. For a category of person (e.g. based on age, sex and state of usual residence), net undercount is the result of Census undercount, overcount, differences in classification between the PES and Census, and imputation error.

Net undercount

The difference between the actual Census count (including imputations) and an estimate of the number of people who should have been counted in the Census. This estimate is based on the Post Enumeration Survey (PES) conducted after each Census. For a category of person (e.g. based on age, sex and state of usual residence), net undercount is the result of Census undercount, overcount, differences in classification between the PES and Census, and imputation error.

Post Enumeration Survey (PES)

The Census Post Enumeration Survey (PES) is a household survey conducted following the Census. The PES allows the ABS to estimate the number of people missed in the Census and the number counted more than once or in error. Historically more people are missed than are counted more than once in Australia, leading to a net undercount. Results from the PES contribute to a more accurate calculation of the estimated resident population on Census night, which is then backdated to 30 June of the Census year.

Rebasing

The 2016 Census of Population and Housing forms the base for newly compiled estimates for 30 June of the Census year, which can be compared with the alternative estimates produced by updating the 2011 Census-based estimates. Of these two estimates, the more recent Census-based estimate is assumed to be the true estimate. To overcome the break in continuity that this implies, population estimates for all years in between the two most recent Censuses are then revised. This complete exercise is known as 'rebasing', as the population estimates are compiled from a new base, the most recent Census.

Regional internal migration estimates (RIME)

Estimates of internal migration for Australia's sub-state areas, prepared primarily using Medicare change of address information.

Regional overseas migration estimates (ROME)

Estimates of overseas migration for Australia's sub-state areas, prepared by breaking down NOM arrivals and NOM departures primarily using Census information.

Rest of state

Within each state and territory, the area not defined as being part of the Greater Capital City Statistical Area is represented by a Rest of state region.

Sex ratio

The sex ratio relates to the number of males per 100 females in a population.

Statistical Area Level 1 (SA1)

An area defined in the Australian Statistical Geography Standard (ASGS) designed as the smallest unit for the release of Census data. They generally have a population of 200 to 800 people, and an average population of about 400 people. SA1s in remote and regional areas generally have smaller populations than those in urban areas. SA1s are used as the building blocks for a number of ASGS defined regions including the Section of State, Urban Centre and Localities and Remoteness Structures. SA1s are also used to approximate a number of administrative regions such as Commonwealth and State Electoral Divisions. There are approximately 57,500 SA1s and they cover the whole of Australia without gaps or overlaps. Population estimates are prepared for SA1s by breaking down estimates from the SA2 level.

Statistical Area Level 2 (SA2)

A medium-sized general purpose area defined in the Australian Statistical Geography Standard built from whole SA1s. Their purpose is to represent a community that interacts together socially and economically. SA2s are based on officially gazetted suburbs and localities. In urban areas, SA2s largely conform to one or more whole suburbs, while in rural areas they generally define the functional zone of a regional centre. SA2s generally have a population range of 3,000 to 25,000 people, and an average population of about 10,000 people. There are approximately 2,300 SA2s and they cover the whole of Australia without gaps or overlaps. SA2s are the base unit for preparing sub-state population estimates.

Statistical Area Level 3 (SA3)

An area defined in the Australian Statistical Geography Standard built up from SA2s to provide a regional breakdown of Australia. SA3s aim to create a standard framework for the analysis of ABS data at the regional level through clustering groups of whole SA2s that have similar regional characteristics. Their boundaries reflect a combination of widely recognised informal regions as well as existing administrative regions such as State Government Regions in rural areas and Local Government Areas in urban areas. SA3s generally range in population from 30,000 to 130,000 people. There are around 360 SA3s and they cover the whole of Australia without gaps or overlaps.

Statistical Area Level 4 (SA4)

An area defined in the Australian Statistical Geography Standard designed for the output of labour force data and to reflect labour markets. In rural areas SA4s generally represent aggregations of multiple small labour markets with socioeconomic connections or similar industry characteristics. Large regional city labour markets are generally defined by a single SA4. Within major metropolitan labour markets SA4s represent sub-labour markets. SA4s are built from whole SA3s. They generally have a population of over 100,000 people to enable accurate labour force survey data to be generated. There are 107 SA4s and they cover the whole of Australia without gaps or overlaps.

Usual residence

in Australia refers to that address at which the person has lived or intends to live for a total of six months or more in a given reference year. For the 30 June reference date, this refers to the calendar year around it.

Quality declaration

Institutional environment

Preparation of estimated resident population (ERP) totals and age-sex breakdowns 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), including the legislative obligations of the ABS, financing and governance arrangements, and mechanisms for scrutiny of ABS operations, please see ABS Institutional Environment.

Relevance

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) 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.

Timeliness

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.

Accuracy

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 the 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 the independently and previously derived 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.

Coherence

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).

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 2017, intercensal sub-state ERP was prepared using regression models, 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.

Interpretability

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 are 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.

Accessibility

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 Data downloads section 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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Abbreviations

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AArea
ABSAustralian Bureau of Statistics
ACAboriginal Council
ACTAustralian Capital Territory
ASGSAustralian Statistical Geography Standard
BBorough
CCity
CensusCensus of Population and Housing
DCDistrict Council
ERPestimated resident population
GCCSAGreater Capital City Statistical Area
LGALocal Government Area
MMunicipality/Municipal Council
NIMnet interstate migration
no.number
NOMnet overseas migration
NSWNew South Wales
NTNorthern Territory
PESPost Enumeration Survey
QldQueensland
RRegional Council
RCRural City
RegCRegional Council
RIMEregional internal migration estimates
ROMEregional overseas migration estimates
SShire
S/Tstate or territory
SASouth Australia
SA1Statistical Area Level 1
SA2Statistical Area Level 2
SA3Statistical Area Level 3
SA4Statistical Area Level 4
TTown
Tas.Tasmania
Vic.Victoria
WAWestern Australia