1216.0.15.002 - Australian Standard Geographical Classification (ASGC) Correspondences, July 2010  
ARCHIVED ISSUE Released at 11:30 AM (CANBERRA TIME) 16/07/2010   
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2010 CORRESPONDENCES PRODUCT BRIEF

Introduction

The Australian Bureau of Statistics (ABS) provides a set of standard correspondence files that enable users to convert data for one type of geographic area to another.

For 2010 the standard correspondences available are:

2010 LGA from 2010 SLA

2010 SLA from 2006 CD

2010 SLA from 2009 SLA

These files are area based correspondences. They provide a ratio of the area of overlap calculated using a GIS system. For example, a 2010 SLA may be made up of 90% of one 2009 SLA plus 35% of another 2009 SLA.

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


File Naming Convention

Character and Meaning

Character Meaning

1 C = Correspondence
2 A = 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

CA2010SLA_2006CD.txt is the text file containing the information concording 2006 Census Collection Districts to 2010 SLAs based on the area correspondence principal.

Note. These files are sometimes known as a CD 2006 to SLA 2010 correspondence, but the ABS express these in the format of 2010SLA from 2006CD because this is the order the data appears in the file.


File Format

Correspondence files are comma-delimited text files.

Field Name Type

To Area Code Character
To Area Name Character
From Area Code Character
From Area Name Character
Ratio Number
Percent Number



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 2010 SLA file will have the name "SLA_2010_Code", and the name field from the 2010 SLA file will have the name "SLA_2010_Name". It is important to note the placement/ positioning convention as it is similar to the file naming convention.

Percentage - figures expressed as a percentage ranges from 0 to 100.

Ratio - figures expressed 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.

“SLA_2006_Code”,”SLA_2006_Name”,”SLA_2005_Code”,”SLA_2005_Name”,”Ratio”,”Percent”

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

plus

105051100 (Botany Bay) = 105055200 (Marrickville) data multiplied by 0.0001

plus

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 2010