1216.0.15.002 - Australian Standard Geographical Classification (ASGC) Correspondences, July 2009  
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The Australian Bureau of Statistics (ABS) provides a set of standard correspondence files that enable users to convert data for one geographic area to another.

For 2009 the standard correspondences available are:
2009 LGA from 2009 SLA
2009 SLA from 2006 CD
2009 SLA from 2008 SLA

These files are area based correspondences. They provide a ratio of the area of overlap calculated using a GIS system. For example a 2009 SLA may be made up of 90% of one 2008 SLA plus 35% of another 2008 SLA.

The file naming is expressed in the form of "to area" = "from area" multiplied by a ratio.

File Naming Convention

Character and Meaning

      1 "C" for Correspondence
      2 "A" for Area Based Correspondence
      3-6 Year of To Area
      7-9 Type of To Area eg, "SLA" *
      10 "_"
      11-14 Year of From Area
      15-17 Type of From Area eg, "SLA" *

* in some cases the Area type is two characters, eg "CD", adjust character count appropriately

For Example

CA2009SLA_2006CD.txt is the text file containing the information concording 2006 Census Collection Districts to 2009 SLAs based on the area correspondence principal.

Note. These files are sometimes known as a CD 2006 to SLA 2009 correspondence, but the ABS express these in the format of 2009SLA from 2006CD because this is the order the data appears in the file.

File Format

Correspondence files are comma-delimited text files.

    Field Names will vary from file to file but are consistent in nature. The field name is constructed from the area type and date. For example the code field from the 2009 SLA file will have the name "SLA_2009_Code", and the name field from the 2009 SLA file will have the name "SLA_2009_Name". It is important to note the placement/ positioning convention as it is similar to the file naming convention.

    Percentage - figure expressed as a percentage ranges from 0 to 100

    Ratio - figures expresses as part of 1 - actual figures can be up to 10 decimal places and are expressed in mathematical terms - 4.77810788750317e-04 which is 0.000477810788750317

    An Example

    An example of an SLA 2005 to SLA 2006 area based correspondence file would be:

    105051100,Botany Bay (C),105051100,Botany Bay (C),0.9795,97.95
    105051100,Botany Bay (C),105055200,Marrickville (A),1.4989195026137e-04,0.01
    105051100”Botany Bay (C),105106550,Randwick (C),4.77810788750317e-04,0.04

    The estimated value for Botany (2006) from 2005 SLA data would be

    105051100 (Botany Bay) = 105055200 (Botany Bay) data multiplied by 0. 9795
    105051100 (Botany Bay) = 105055200 (Marrickville) data multiplied by 0.0001
    105051200 (Botany Bay) = 105106550 (Randwick) data multiplied by 0.0004

    Copyright Commonwealth of Australia administered by the ABS.

    For enquiries please contact the ABS Geography Section, see details below.

    ABS Geography Section

    Email: geography@abs.gov.au

    July 2009