STATISTICAL AREA LEVEL 4 (SA4)
The SA4 regions are the largest sub-State regions in the Main Structure of the ASGS. They are designed for the output of labour force data and reflect labour markets within each State and Territory within the population limits imposed by the Labour Force Survey sample. SA4s provide the best sub-state socio-economic breakdown in the ASGS.
SA4s are built from whole SA3s. Whole SA4s aggregate directly to S/Ts in the Main Structure and GCCSAs. SA4s do not cross S/T borders. There are 88 SA4 spatial units. In aggregate, they cover the whole of Australia without gaps or overlaps.
DELIMITATION OF SA4
Listed below are the criteria for the delimitation of SA4s.
A minimum of 100,000 persons was set for the SA4s, although there are some exceptions to this. In regional areas, SA4s tend to have populations closer to the minimum (100,000 - 300,000). In metropolitan areas, the SA4s tend to have larger populations (300,000 - 500,000).
Labour markets were a key consideration in the design of SA4s. The reason for this is that Labour force data has two geographic components to it - the labour supply (where people live) and demand (where people work). For statistical purposes, it is ideal to maximise the extent to which the data output region spatially contains both sets of geographic locations. Labour markets are geographic regions, which reflect the high degree of interconnectivity between the labour supply and demand. By reflecting labour markets, the output data is relevant to both labour supply and demand.
The ABS consulted with a number of experts on labour market geography to identify labour markets within Australia. The resulting labour markets were characterised by a large number of very small regional labour markets, a smaller number of medium sized labour markets around regional centres, and very large labour markets representing the major metropolitan centres. While this may be an accurate reflection of Australian labour markets, many regions do not meet the minimum population criterion.
The smaller regional labour markets were amalgamated based on travel to work interactions as well as industry and regional similarities to create SA4s of approximately 100,000 to 300,000 persons. The medium sized regional centre labour markets that exceeded 100,000 persons (for example Cairns, Qld) were preserved as far as possible as SA4s that directly represent the labour market, though in some cases small closely related labour markets were included in these SA4s. The very large major metropolitan labour markets were split to reflect major employment hubs and their primary labour supply catchments. These are generally larger population SA4s, 300,000 to 500,000 persons, reflecting the fact that they represent labour markets with large populations.
Special Purpose SA4
There are non-spatial SA4s for Migratory - Offshore - Shipping and No Usual Address in each S/T.
The key criteria for SA4 names are that they be:
- have a maximum of 40 characters
- unique, i.e. not shared by any other SA4 in Australia.
SA4s are named according to the areas they represent:
SA4 CODING STRUCTURE
- where an SA4 represents a labour market of a major city it is named after that city, for example:
- where an SA4 represents an employment centre within a larger city it is generally named to reflect both the larger city and the employment centre or part of the city that it represents, for example:
- Melbourne - Inner South
- Sydney - Blacktown
- where an SA4 represents a collection of labour markets in regional areas it is named using either a description of that part of the S/T or after one or more well-known regional areas that it closely replicates, for example:
- where this name does not identify it within Australia, it is generally preceded by the S/T name, for example:
- Western Australia - Wheat Belt
- Queensland - Outback.
An SA4 is identified by a 3-digit hierarchical code. This comprises a 1-digit S/T identifier, which precedes a 2-digit SA4 identifier, which is unique within each S/T.
102 Central Coast
Future Allocation of SA4 Codes
|S/T ||SA4 ||SA4 Name |
|1 ||02 ||Central Coast |
In the future, it may be necessary to allocate new codes. If an SA4 is abolished, or changes significantly between editions of the ASGS, the SA4 identifier will be retired and the replacement SA4(s) given the next available previously unused SA4 identifier within the S/T.
SA4 Identifier Ranges
Within each State, the SA4 identifier is in the range 01- 79. SA4 identifiers in the range 80-99 are reserved for special purpose SA4s.