The Australian Statistical Geography Standard (ASGS) provides a framework of statistical areas used by the Australian Bureau of Statistics (ABS) and other organisations to enable the publication of statistics that are comparable and spatially integrated. First introduced in 2011, the ASGS replaced the Australian Standard Geographical Classification (ASGC) that had been in use since 1984. The ASGS provides users with an integrated set of standard areas that they can use to access, visualise, analyse and understand statistics produced by the ABS and other organisations.
The ASGS is split into two parts, the ABS Structures and the Non ABS Structures.
The ABS Structures are areas that the ABS designs specifically for outputting statistics. This means that the statistical areas are designed to meet the requirements of specific statistical collections as well as geographic concepts relevant to those statistics such as remoteness and urban/rural definitions. This helps to ensure the confidentiality, accuracy and relevance of the data. The ABS Structures are stable for five years to enable better comparison of data over time.
The Non ABS Structures represent administrative areas for which the ABS is committed to providing a range of statistics. These areas can change regularly as they are not defined by the ABS. As a result the Non ABS Structures are updated annually if significant changes to the areas have occurred. This improves the relevance of ABS data released on these areas. For example, the Local Government Areas (LGAs) are released annually: these represent LGAs that are defined by the State and Territory governments. ABS statistics such as Estimated Resident Population (ERP) are output on these LGA approximations.
Separating the ABS and Non ABS Structures in the ASGS ensures that the ABS can provide statistics on both stable, purpose built statistical areas as well as important administrative areas. This is a key difference to the previous ASGC where all areas were related to LGAs and consequently needed to be updated annually to reflect changes in the LGAs. This key difference is possible because the ASGS uses Mesh Blocks as a common building block for all structures. Mesh Blocks, like other ABS Structures, are stable for 5 years. However, they are small enough that they can accurately approximate the changing administrative areas without changing themselves. Mesh Blocks also provide an additional level of confidentiality for data released on the ASGS, as the difference in data released on multiple statistical areas is always at least one Mesh Block.
The ABS Structures are a hierarchy of areas developed for the release of ABS statistical information. Their components are described below.
Diagram 1 depicts the various ABS Structures, their component statistical areas and how they interrelate.
Diagram 1: ASGS ABS Structures
- Mesh Blocks (MBs) are the smallest geographical area defined by the ABS. They are designed as geographic building blocks rather than as areas for the release of statistics themselves. All statistical areas in the ASGS, both ABS and Non ABS Structures, are built up from Mesh Blocks. As a result the design of Mesh Blocks takes into account many factors including administrative boundaries such as Cadastre, Suburbs and Localities and LGAs as well as land uses and dwelling distribution. Most Mesh Blocks contain 30 to 60 dwellings although some are specifically designed to have zero. This provides an additional level of confidentiality for data released on the ASGS as the difference in data released on multiple statistical areas is always at least one Mesh Block. Mesh Blocks, like other ABS structures, are stable for 5 years and are updated to reflect changes such as new housing developments every 5 years. Mesh Blocks include a Mesh Block Category that broadly defines primary land uses such as Residential and Commercial. The only statistical data currently available for Mesh Blocks (as of 2017) are total population and dwelling counts from the Census of Population and Housing.
- Statistical Areas Level 1 (SA1s) are designed to maximise the spatial detail available for Census data. Most SA1s have a population of between 200 to 800 persons with an average population of approximately 400 persons. This is to optimise the balance between spatial detail and the ability to cross classify Census variables without the resulting counts becoming too small for use. SA1s aim to separate out areas with different geographic characteristics within Suburb and Locality boundaries. In rural areas they often combine related Locality boundaries. SA1s are aggregations of Mesh Blocks.
- Statistical Areas Level 2 (SA2s) are designed to reflect functional areas that represent a community that interacts together socially and economically. They consider Suburb and Locality boundaries to improve the geographic coding of data to these areas and in major urban areas SA2s often reflect one or more related suburbs. The SA2 is the smallest area for the release of many ABS statistics, including the Estimated Resident Population (ERP), Health & Vitals and Building Approvals data. SA2s generally have a population range of 3,000 to 25,000 persons, and have an average population of about 10,000 persons. SA2s are aggregations of whole SA1s.
- Statistical Areas Level 3 (SA3s) are designed for the output of regional data. SA3s create a standard framework for the analysis of ABS data at the regional level through clustering groups of SA2s that have similar regional characteristics, administrative boundaries or labour markets. SA3s generally have populations between 30,000 and 130,000 persons. They are often the functional areas of regional towns and cities with a population in excess of 20,000, or clusters of related suburbs around urban commercial and transport hubs within the major urban areas. SA3s are aggregations of whole SA2s.
- Statistical Areas Level 4 (SA4s) are specifically designed for the output of Labour Force Survey data and reflect labour markets within each State and Territory within the population limits imposed by the Labour Force Survey sample. Most SA4s have a population above 100,000 persons to provide sufficient sample size for Labour Force estimates. In regional areas, SA4s tend to have lower populations (100,000 to 300,000). In metropolitan areas, the SA4s tend to have larger populations (300,000 to 500,000). SA4s are aggregations of whole SA3s.
- State and Territory (S/T) and Australia are spatial units separately representing the geographic extent of Australia, and the States and Territories within Australia. Jervis Bay Territory, the Territories of Christmas Island, Cocos (Keeling) Islands and Norfolk Island are included as one spatial unit at the State and Territory level under the category of Other Territories. Prior to 2016 Norfolk Island was not included in the ASGS. In line with Australian Government announced reforms to the governance of Norfolk Island and its inclusion into the definition of Geographic Australia, the 2016 ASGS has been updated to include the Territory of Norfolk Island.
Greater Capital City Statistical Area Structure
Greater Capital City Statistical Areas (GCCSAs) are designed to represent the functional extent of each of the eight State and Territory capital cities. They include the people who regularly socialise, shop or work within the city, but live in the small towns and rural areas surrounding the city. GCCSAs are not bound by a minimum population size criterion. GCCSAs are built from SA4s.
Significant Urban Area Structure
Significant Urban Areas (SUAs) represent individual Urban Centres or clusters of related Urban Centres with a core urban population over 10,000 persons. They can also include: related peri-urban areas, satellite development, the area into which the urban development is likely to expand and nearby rural land. SUAs are aggregations of SA2s which enables them to provide a broad range of regularly updated ABS demographic and social statistics that are not available for the SA1 based Urban Centres and Localities.
- Indigenous Locations (ILOCs) represent small Aboriginal and Torres Strait Islander communities (urban and rural) with a minimum population of 90 Aboriginal and Torres Strait Islander usual residents. An ILOC is an area designed to allow the release of statistics relating to Aboriginal and Torres Strait Islander people with a high level of spatial accuracy whilst maintaining the confidentiality of individuals. ILOCs are aggregates of one or more SA1s.
- Indigenous Areas (IAREs) are medium sized geographical areas designed to facilitate the release of more detailed statistics for Aboriginal and Torres Strait Islander Peoples. IAREs provide a balance between spatial resolution and population size, which provides the ability to release more detailed socio-economic attribute data than is available on ILOCs. IAREs are aggregates of one or more ILOCs.
- Indigenous Regions (IREGs) are large geographical areas loosely based on the former Aboriginal and Torres Strait Islander Commission boundaries. The greater population of IREGs enables greater cross classification of variables when compared with IAREs and ILOCs. IREGs do not cross State or Territory borders and are aggregates of one or more IAREs.
Urban Centres and Localities (UCLS) and Section of State Structures (SOS)
The Urban Centres and Localities (UCLs), and Section of State (SOS) represent areas of concentrated urban development. This is defined using aggregations of SA1s which meet population density criteria or contain other urban infrastructure. The SOS classification groups the UCLs up into classes of urban areas based on population size. SOS does not explicitly define rural Australia; however, in practice, any population not contained in an Urban Centre or Locality is considered to be Rural Balance in the SOS classification.
Remoteness Areas (RAs)
Remoteness Areas (RAs) divide Australia and the States and Territories into 5 classes of remoteness on the basis of their relative access to services. RAs are based on the Accessibility and Remoteness Index of Australia (ARIA+), produced by the Australian Population and Migration Research Centre at the University of Adelaide. RAs are aggregates of SA1s that are grouped together based on their average ARIA+ score.
The Non-ABS Structures comprise eight regions which are not defined or maintained by the ABS, but for which the ABS is committed to providing a range of statistics. They generally represent administrative regions and are approximated by Mesh Blocks, SA1s or SA2s. They are:
- Local Government Areas
- Postal Areas
- State Suburbs
- Commonwealth Electoral Divisions
- State Electoral Divisions
- Australian Drainage Divisions
- Natural Resource Management Regions
- Tourism Regions
Diagram 2 depicts the various ASGS Non-ABS Structures, their component regions and how they interrelate.
Diagram 2: ASGS Non-ABS Structures
RELEASE OF THE ASGS
The regions that are defined in the ABS Structures are updated on a five yearly basis aligning with the Census of Population and Housing to provide a balance between stability and relevance to the changing underlying geography. The ABS Structures are published in Volumes 1, 2, 4 and 5 of the ASGS and the release of these is timed for use with Census data.
The Non ABS Structures are also updated in line with this five yearly Census cycle, these are published in Volume 3 of the ASGS. To accommodate the degree of change in Local Government Area (LGA) boundaries, these are updated as part of Volume 3 annually in July each year. This enables ABS statistics to be released on the most up to date LGAs.
All ASGS publications can be found on the ABS Geography Publications webpage.
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