3218.0 - Regional Population Growth, Australia, 2016 Quality Declaration 
Latest ISSUE Released at 11:30 AM (CANBERRA TIME) 28/07/2017   
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EXPLANATORY NOTES


INTRODUCTION

1
This release contains estimates of the resident population of Statistical Areas Level 2 to 4 (SA2s - SA4s) and Greater Capital City Statistical Areas (GCCSAs) of Australia. These estimates plus those for Local Government Areas (LGAs), Significant Urban Areas (SUAs), Remoteness Areas (RAs) and Electoral Divisions are also provided in the Downloads tab of this issue.

2
To meet the competing demands for accuracy and timeliness, there are several versions of sub-state population estimates. Preliminary estimates as at 30 June are normally available by April 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 2011 and preliminary rebased for 2012 to 2016, based on the results of the 2016 Census.


ESTIMATED RESIDENT POPULATION - AUSTRALIA


3
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.

4
Estimates of the resident population are 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. A person is regarded as a usual resident if they have been (or expected to be) residing in Australia for a period of 12 months or more over a 16-month period.

5
Population estimates for Australia and the states and territories 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 the states and territories, account is also taken of estimated interstate movements involving a change of usual residence. After each Census, estimates for the preceding intercensal period are finalised (rebased) by incorporating an additional adjustment (intercensal difference) to ensure that the difference between the ERPs at the two respective Census dates agrees with the total intercensal change.

6
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).


ESTIMATION OF SUB-STATE POPULATIONS


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 Immigration and Border Protection. As the Census is not held on 30 June (the 2016 Census was held on 9 August), further adjustments taking into account 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 to the unconfidentialised ERP.

9
For post-Census years, the absence of migration data at the SA2 level means that it is not possible to estimate SA2 populations by taking into account natural increase and net migration. Instead, ERP for most SA2s is calculated using a mathematical model, where relationships are established between changes in population and changes in indicator data between the two most recent Censuses for groups of SA2s. Current indicators include dwelling approvals, Medicare enrolments and counts of people on the Australian Electoral Roll. Changes in these indicators are used to estimate changes in the population of each area since the last Census. In areas where indicator data is unreliable or migration can be assumed to be insignificant, population change may be estimated by adding natural increase (births minus deaths) since the previous Census. In some very small areas, population change since the previous Census may be assumed to be zero in the absence of reliable indicator data for these areas. All estimates are scrutinised and validated by ABS analysts. Local knowledge, such as that advised by local and 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/territory population estimates.

10
To enable the comparison of regional populations over time, historical population estimates based on consistent updated geographic boundaries are prepared. These estimates correspond with previously released estimates (on different boundaries) where possible. When official statistical boundaries, such as Local Government Areas, are updated, historical estimates are prepared based on the updated boundaries.

11
In Census years, both preliminary estimates (derived from updating ERP from the previous Census) and rebased 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 based on estimates derived by apportioning the intercensal difference across the five years, while constraining the SA2 level estimates so that they sum to state/territory 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. Intercensal difference was apportioned based on the unrebased growth rate for some areas (e.g. newly established areas) where necessary.


ACCURACY OF SUB-STATE POPULATION ESTIMATES


12
An indication of the accuracy of ERPs can be gauged by assessing the size and direction of the intercensal differences. For Australia, the preliminary (unrebased) June 2016 ERP over-estimated the preliminary rebased June 2016 ERP by 0.3% (78,700 people). For the states and territories, the 2016 intercensal differences ranged from -2.2% (Western Australia) to +1.8% (Victoria and Australian Capital Territory).

13
Summary statistics of the absolute values of these differences can be used to assess the accuracy of a number of population estimates. To give an indication of the quality of SA2-based estimates, unrebased estimates for 2016 were prepared for 2016 SA2s, and constrained to preliminary rebased state/territory ERP. These estimates were compared with the preliminary rebased 2016 SA2 estimates. The average absolute value of the intercensal differences for this series of 2016 SA2 estimates (excluding areas with less than 1,000 people) was 3.5%.

14
Average absolute intercensal differences for the 2016 SA2 estimates generally decreased with increasing population size; that is, SA2s with large populations recorded the smallest percentage errors while small SA2s had the largest percentage errors.

Average absolute intercensal difference, Australia - 30 June 2016

Number of SA2s
Average absolute intercensal difference
Size of SA2 (people)
no.
%

1,000 to 2,999
94
5.2
3,000 to 4,999
332
4.6
5,000 to 6,999
315
3.7
7,000 to 9,999
367
3.9
10,000 to 14,999
465
3.1
15,000 to 19,999
314
2.5
20,000 and over
268
2.6



15
In recognition of the inherent inaccuracy 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. Estimates of change in population are based on unrounded numbers.


SA1-BASED POPULATIONS


16
The Statistical Area Level 1 (SA1) is the smallest geographic unit for the release of Census data. There are approximately 57,000 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. These estimates can be aggregated to form population estimates for regions such as State Suburbs, Remoteness Areas and Electoral Divisions. By this means, population estimates for areas other than those provided in this product (including SA1 ERPs) may be available on request.

17
Population estimates at the SA1 level as at 30 June of a Census year are compiled by apportioning the population estimate for each SA2 across the SA1s within the SA2, using Census usual residence counts. In intercensal years, the 30 June population estimates for SA2s are apportioned across SA1s by taking into account population change implied by indicator data at the SA1 level in the years following the Census.


LOCAL GOVERNMENT AREA POPULATIONS


18
Population estimates for LGAs that can be built from whole SA2s or SA1s are produced by aggregating the SA2 or SA1 level estimates accordingly. In Census years, where LGAs cross SA1 boundaries, Mesh Block Census counts are used to estimate the share of the SA1 population that reside in those LGAs. In post-Census years, estimates are prepared using updated estimates of SA1 to LGAs splits, taking into account population change implied by indicator data. Whole and partial SA1 estimates are then aggregated to LGA level.


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 2016 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 departments. 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.
  • Commonwealth Electoral Divisions (CEDs). A CED is an area legally prescribed for returning one member to the House of Representatives, Australia's Federal Lower House of Parliament. Data for CEDs are approximated by aggregating the data for SA1s that best fit the area.
  • State Electoral Divisions (SEDs). An SED is an area legally prescribed for returning one or more members to the State or Territory Lower Houses of Parliament. Data for SEDs are approximated by aggregating the data for Statistical Areas Level 1 (SA1) that best fit the area.

21 This product also contains data presented according to the 2011 edition of the Australian Statistical Geography Standard (ASGS) - Non ABS Structures.
  • Remoteness Areas (RAs). RAs represent an aggregation of non-contiguous geographical areas which share common characteristics of remoteness. The delimitation criteria for RAs are based on the Accessibility/Remoteness Index of Australia (ARIA+), which measures the remoteness of a point based on the road distance to the nearest urban centre. The RA categories range from Major Cities to Very Remote. Each RA is created from a grouping of SA1s which have a particular degree of remoteness. The 2016 ASGS-based Remoteness Structure, calculated using the results of the 2016 Census, is scheduled for release early 2018. ERP by 2016 ASGS-based RAs will be prepared for the next issue of this product.
  • Significant Urban Areas (SUAs). SUAs are aggregations of whole SA2s which represent concentrations of urban development with populations of 10,000 people or more. They do not necessarily represent a single Urban Centre, as they can represent a cluster of related Urban Centres with a core urban population over 10,000 people. They can also include related peri-urban and satellite development and the area into which the urban development is likely to expand. SUAs may cross a state or territory border. The 2016 ASGS-based SUAs are scheduled for release late 2017. ERP by 2016 ASGS-based SUAs will be prepared for the next issue of this product.

22 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 2016 (cat. no. 1270.0.55.003)
Australian Statistical Geography Standard: Volume 4 - Significant Urban Areas, Urban Centres and Localities, Sections of State, July 2011 (cat. no. 1270.0.55.004)
Australian Statistical Geography Standard: Volume 5 - Remoteness Structure, July 2011 (cat. no. 1270.0.55.005)

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


RANKING POPULATION CHANGE


24 This product ranks regions according to both 'largest' and 'fastest' growth, identifying areas with significant changes in population. Largest growth is based on the absolute change in population between June 2006 and June 2016, while fastest growth is based on the rate of change in population (expressed as a percentage). Regions with populations of less than 1,000 people at June 2016 have been excluded from the fastest growth rankings.

25 Due to the inherent imprecision of regional population estimates and variation in population size, rankings should be considered indicative of relative growth between regions, not definitive.


CENTRE OF POPULATION


26 The centre of population is a measure used to describe the spatial distribution of a population. The method used to calculate centres of population in this product is based on the centroid and population of each Statistical Area Level 1 (SA1). To calculate the centre of population for an area, the latitude and longitude coordinates of the centroid of each SA1 in that area are multiplied by the SA1's ERP to obtain weighted latitudes and longitudes for each SA1. These are summed to obtain a weighted latitude and longitude coordinate for the area, then divided by the total population of the area to obtain a single latitude and longitude coordinate.

27 Due to the inherent imprecision in small area estimates, the centre of population should be considered indicative only of the distribution of population, and cannot be ascribed to an exact location. The use of different geographical level data can result in different centres of population.


CALCULATION OF AREAS AND POPULATION DENSITY


28 The area figures used in this issue are based upon the SA2 level of the 2016 edition of the ASGS. The areas of the SA2s were calculated using ABS standard Geographic Information Systems software from the digital boundaries of this ASGS edition. Higher level spatial unit area figures are aggregations of the relevant SA2 areas. These areas are included in the SA2-based spreadsheet accompanying this release. Area figures are also provided for LGAs based on the 2016 edition of the ASGS and can be found in the LGA-based spreadsheet.

29 The population density of an area as featured in the Excel spreadsheets in this product have been calculated by dividing its estimated resident population by its area in square kilometres. The result is expressed as a number of people per square kilometre.


POPULATION GRID

30 In this release estimated resident population data has also been published in 1km˛ grid format. The population grid offers a consistently sized spatial unit and gives a refined model of population distribution, particularly for the non-urban areas of Australia. It is also an established, easy to understand and readily comparable international standard which will enable users to make local, national and international comparisons of population density.

31 The population grid was modelled using preliminary rebased 2016 SA1 ERP. All SA1s with an ERP greater than zero were identified. Within these SA1s all residential dwelling locations were identified using a variety of sources including the Geocoded National Address File (GNAF).Within each populated SA1 the 2016 SA1 ERP was distributed equally across all the residential dwellings. The average value assigned to each dwelling was then summed within each 1km˛ grid cell across the country. For more information on the population grid see here.

32 The population grid is provided in three formats:
  • ESRI Grid format which can only be opened in a Geographic Information System (GIS).
  • GeoTIFF format is a Tagged Image File Format (TIFF). It is a raster graphics file format that is widely supported by graphics software. The Geo extension to the TIFF format is a metadata storage format which allows georeferencing information (datums, ellipsoid, coordinate systems, map projection) to be embedded within the TIFF file. These metadata allows Geographical Information Systems (GIS) software, such as MapInfo, ArcGIS or QGIS, to correctly interpret the location of the image and compare the image with other spatial referenced data.
  • PNG format is a Portable Network Graphics File (PNG). It is a raster graphics file format that is widely supported by graphics software including those bundled with the major operating systems (Microsoft Windows, Apple OS X & iOS). The objective of publishing in PNG format is to allow users to quickly visualise a "picture" of these data.


ACKNOWLEDGMENT


33 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


34 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)
Population by Age and Sex, Regions of Australia (cat. no. 3235.0)
Births, Australia (cat. no. 3301.0)
Deaths, Australia (cat. no. 3302.0)
Migration, Australia (cat. no. 3412.0) - includes regional internal migration estimates
Australian Historical Population Statistics (cat. no. 3105.0.65.001)
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


35 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 that you provide to us.