STATISTICAL AREA LEVEL 2 (SA2)

The SA2s are a general-purpose medium-sized area built from whole SA1s. Their aim is to represent a community that interacts together socially and economically.

Whole SA2s aggregate directly to SA3s in the Main Structure, as well as Significant Urban Areas. SA2s do not cross S/T borders. There are 2,196 SA2 spatial units. In aggregate, they cover the whole of Australia without gaps or overlaps. Jervis Bay Territory, the Territory of the Cocos (Keeling) Islands and the Territory of Christmas Island are each represented by an SA2.

The SA2 is the lowest level of the ASGS structure for which Estimated Resident Population (ERP), Health and Vitals and other non-Census ABS data are generally available.


DELIMITATION OF SA2

The SA2s were delimited using a number of criteria. The design reflects a balance between the respective considerations.

Listed below are the criteria in the approximate order of importance.

Population

SA2s generally have a population range of 3,000 to 25,000 persons, and have an average population of about 10,000 persons. SA2s in remote and regional areas generally have smaller populations than those in urban areas. There are some SA2s outside these bounds, due to other considerations such as:

• the relative sparseness of the population in remote regions (an SA2 with a population of 3,000 may cover too large and diverse a geographical area to be a meaningful unit)
• the benefit of preserving recognisable areas for which there is a considerable amount of historical data
• isolated geographical areas, such as islands or other isolated populations
• the need to avoid arbitrary subdivisions of otherwise coherent regions, such as very large suburbs or regional towns.

Functional

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.

Growth

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:

• a shared road network
• shared community facilities
• LGA boundaries
• shared historical or social links
• socio-economic similarity.

LGA

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:

• it closely aligned with gazetted suburb boundaries
• it reflected the underlying settlement pattern
• it represented the functional area of a regional town or city
• had a high degree of recognition amongst stakeholders
• it aligned to a significant recognisable geographical feature.

Zero SA2

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:

• major infrastructure (ports, airports)
• significant bodies of water
• major commercial and industrial zones
• national parks
• defence land
• very large urban parks
• very large sporting precincts.

Special Purpose SA2

There are non-spatial SA2s for Migratory - Offshore - Shipping and No Usual Address in each S/T.


SA2 NAMES

The key criteria for SA2 names are that they be:

• meaningful
• have a maximum of 40 characters
• unique, i.e. not shared by any other SA2 in Australia.

In large urban areas, SA2s are named for the gazetted suburbs that comprise them:

• where an SA2 is made from a single suburb, it will retain the name of the suburb, for example:
  • Duffy
• where a single large suburb is split into more than one SA2, it will retain the name of the suburb and a geographic identifier, for example:
  • Mount Waverley - South
  • Mount Waverley - North
• where an SA2 is made up from 2 or 3 suburbs, then the SA2 name is a concatenation of the suburb names, for example:
  • Waratah - North Lambton
  • Bayswater - Embleton - Bedford
• where an SA2 is made up of 4 or more suburbs it will be named for the larger or more prominent suburbs, or given a local identifier, for example:
  • Homebush Bay - Silverwater
  • Pioneer Valley.

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:

• Goulburn
• Benalla Region
• Townsville - South
• Bulahdelah - Stroud.

Where an SA2 name is duplicated in two or more S/Ts, the S/T abbreviation is attached to the SA2 name, for example:

• O'Connor (ACT)
• O'Connor (WA).

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.

9-digit Code

A 9-digit SA2 code is fully hierarchical, and comprises: S/T identifier, SA4 identifier, SA3 identifier, SA2 identifier.

Example:

503021041 Perth City

S/T	SA4	SA3	SA2	SA2 Name
5	03	02	1041	Perth City

5-digit Code

A 5-digit SA2 code is not hierarchical, and comprises only S/T identifier, SA2 identifier.

Example:

51041 Perth City

S/T	SA2	SA2 Name
5	1041	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.

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