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STATISTICAL AREA LEVEL 2 (SA2)
A functional area is the area from which people come to access services at a centre. This centre may be a rural town, a regional city, a commercial and transport hub within a major city, or the major city itself. The concept of a functional area is used at all levels of the ABS Main Structure, but is essential to the design of the SA2s outside major urban areas. A centre and its functional area are represented by one or more SA2s. A rural town and its functional area may be combined into a single SA2. A larger town may be identified by its own SA2 and its functional area by a second SA2. Larger towns and regional cities may be represented by several SA2s, as may their functional areas.
Within cities, the SA2s represent gazetted suburbs rather than functional areas. See below for more detail.
In remote areas, it is difficult to apply the concept of a functional area without creating regions which are too large and diverse. In remote areas, the SA2s were designed to represent meaningful regions, useful for statistical analysis.
SA2s containing regional towns or on the fringes of larger cities have been designed to contain: the urban area, any immediately associated semi urban development and likely growth in the next 10 to 20 years. This is to ensure that the SA2 boundaries remain stable over several Population Censuses.
Gazetted Suburbs and Localities
Where possible, the SA2s have been designed around whole gazetted suburbs or rural localities. This is to make the regions as meaningful as possible to users unfamiliar with the statistical geography and to facilitate address coding to the various units of the ASGS.
In regional and remote areas, gazetted localities were usually too small to represent an SA2 in their own right and were combined on the basis of whether they formed part of a functional area.
In the major cities, SA2s often represent single suburbs. Suburb size is variable within and between cities and they do not always make a convenient region to be used directly as an SA2. Where this occurs five general criteria have been used to cluster smaller suburbs together or break up extremely large suburbs:
LGA boundaries were considered in the design of the SA2s and were often adopted where the LGA boundary satisfied one or more of the following:
Zero SA2s have a nil or nominal population. They are created to represent large unpopulated areas that are not easily combined with surrounding populated SA2s.
They may include:
Special Purpose SA2
There are non-spatial SA2s for Migratory - Offshore - Shipping and No Usual Address in each S/T.
The key criteria for SA2 names are that they be:
In large urban areas, SA2s are named for the gazetted suburbs that comprise them:
In rural areas, SA2s are named for the gazetted localities that comprise them, or the towns, city, or region with which they are associated, for example:
Where an SA2 name is duplicated in two or more S/Ts, the S/T abbreviation is attached to the SA2 name, for example:
SA2 CODING STRUCTURE
An SA2 is identifiable either by a 9-digit fully hierarchical code, or by a truncated 5-digit code comprising the S/T and SA2 identifiers. The SA2 identifier is a 4-digit code, assigned in alphabetical order within an SA3. An SA2 code is only unique within an S/T if it is preceded by the S/T identifier.
A 9-digit SA2 code is fully hierarchical, and comprises: S/T identifier, SA4 identifier, SA3 identifier, SA2 identifier.
503021041 Perth City
A 5-digit SA2 code is not hierarchical, and comprises only S/T identifier, SA2 identifier.
51041 Perth City
Future Allocation of SA2 Codes
In the future, it may be necessary to allocate new codes. If an SA2 is abolished, or changes significantly between editions of the ASGS, the SA2 identifier will be retired and the replacement SA2(s) given the next available previously unused SA2 identifier within the S/T.
SA2 Identifier Ranges
Within each S/T, the SA2 identifier is in the data range 0001-7999. SA2 identifiers in the range 8000-8999 are reserved for processing within the ABS. The range 9000 to 9999 is reserved for special purpose SA2s.