The options available for converting data to the ASGS depends largely on the information stored with a user's unit record data. If a set of full addresses are available, or latitude and longitude coordinates are stored with the unit records, then geocoding the data to the new geography should be utilised as the most accurate method of converting the data.
If only partial address information is available, then coding indexes may be used to convert data to the ASGS. It needs to be noted that this will only be possible to the higher levels of the ASGS.
Allocation tables can be used if unit record data is contained at the finer levels of the ASGS. However, these tables can only be used to aggregate data to higher levels of the ASGS. They cannot be used to disaggregate data from higher levels of the ASGS.
If these options cannot be utilised, then a correspondence may be used to convert data to the ASGS. However, there are a number of issues that need to be investigated when using a correspondence. Correspondences work best when converting data from small regions onto large regions, and where the conversion is weighted by related criteria. Caution should always be taken when analysing the results of data that have been converted using correspondences, and the potential limitations of the data taken into account. A quality indicator will be incorporated in the future to ABS correspondences to assist users in determining whether they are fit for purpose.
Further information on converting data to the ASGS can be found by visiting the ABS Statistical Geography web site: http://www.abs.gov.au/geography. Contact us for additional information or support.