1216.0.55.004 - Information Paper: Converting Data to the Australian Statistical Geography Standard, 2012  
ARCHIVED ISSUE Released at 11:30 AM (CANBERRA TIME) 28/02/2012  First Issue
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CODING INDEXES

Coding indexes enable data collected with a partial address to be linked to a geographic area. For ABS purposes, coding indexes are tables that list a geographic area against its most appropriate match in the ASGS. For example, a coding index will indicate a Locality and the SA2 it is most appropriately associated with based on the distribution of population within the locality. Table 1 shows an example of a Locality to SA2 coding index.

Table 1: Example of Locality to SA2 Coding Index

LOCALITY NAME STATE POSTCODE SA2 MAINCODE 2011 SA2 NAME 2011

IRYMPLE VIC 3498 215021395 Irymple
NICHOLS POINT VIC 3501 215021395 Irymple
NICHOLS PT VIC 3501 215021395 Irymple
EAST MILDURA VIC 3500 215021397 Mildura
MILDURA VIC 3500 215021397 Mildura
MILDURA EAST VIC 3500 215021397 Mildura
MILDURA SOUTH VIC 3500 215021397 Mildura
MILDURA WEST VIC 3500 215021397 Mildura
SOUTH MILDURA VIC 3500 215021397 Mildura
WEST MILDURA VIC 3500 215021397 Mildura
HATTAH VIC 3501 215021398 Mildura Region
KOORLONG VIC 3501 215021398 Mildura Region
LINDSAY POINT VIC 3496 215021398 Mildura Region
LINDSAY PT VIC 3496 215021398 Mildura Region
MERINEE VIC 3496 215021398 Mildura Region
MERINGUR VIC 3496 215021398 Mildura Region
MERRINEE VIC 3496 215021398 Mildura Region
NEDS CORNER VIC 3496 215021398 Mildura Region
WARGAN VIC 3496 215021398 Mildura Region
WERRIMULL VIC 3496 215021398 Mildura Region
KARADOC VIC 3496 215021399 Red Cliffs
RED CLIFFS VIC 3496 215021399 Red Cliffs
SUNNYCLIFFS VIC 3496 215021399 Red Cliffs



The coding index in Table 1 lists a series of Locality names, along with State and Australia Post postcode. For each Locality it then lists the associated SA2 Code and SA2 Name. In cases where users have unit record data that does not contain whole addresses, but does contain Suburb/Locality and Australia Post postcode information, an accurate match to the SA2 level of the ASGS can be obtained. In this instance the Australia Post postcode is important as Locality names are not necessarily unique, even within a State - the postcode aids in identifying the correct Locality.

Care should be taken when applying coding indexes, as the transformed areas may not be wholly within their associated ASGS region. Coding indexes do not apportion data - they assign whole areas to the most appropriate region within the new geography. As a general rule, small areas can be assigned more accurately than large areas.

During the development of the ASGS, SA2 boundaries were designed to reflect officially gazetted Suburb and Locality boundaries. As a result, if collection units contain this level of information, they can be accurately coded to the SA2 level of the ASGS. The ABS will supply this index free of charge, and it is available upon request through our Contact us page.

Similarly, coding indexes have been created that enable users to match postcode data to the SA4 and Greater Capital City Statistical Area (GCCSA) boundaries, as well as 2006 Remoteness Areas and 2011 Statistical Divisions (SD).

There are issues that users need to be aware of when using postcode data as the sole source of deriving a match to the ASGS however. Firstly, there is no definitive set of postcode boundaries available, as Australia Post does not maintain a definitive set of boundaries as a matter of course. Various organisations have created their own boundaries, but these can differ quite significantly from one dataset to another. Another issue is that postcodes do not cover the whole of Australia. Postcodes are also, in general, larger than Suburbs and as a result cannot be coded to the more detailed levels of the ASGS. As a result, these coding indexes will only be released at the SA4 and GCCSA levels as the quality of these coding indexes at this level are deemed to be acceptable.