2905.0.55.001 - ABS Postal Area Concordances, Aug 2006  
ARCHIVED ISSUE Released at 11:30 AM (CANBERRA TIME) 02/07/2007  First Issue
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Postal Area from Statistical Local Area 2006 Concordance

PRODUCT BRIEF



The Australian Bureau of Statistics (ABS) has developed several concordance products that enable users to convert data for one type of geographic area to another.

The Postal Area from Statistical Local Area (POA from SLA) concordance for 2006 allows the conversion of population data from Statistical Local Areas (SLAs) to Postal Areas (POA). For full details of these geographic areas please refer to: Statistical Geography Volume 1 Australian Standard Geographical Classification (ASGC) 2006 (cat no. 1216.0) for SLAs; and Statistical Geography Volume 2 Census Geographic Areas Australia 2006 (cat no. 2905.0) for POAs.

This population weighted concordance can be used to translate statistics aggregated by SLA to POA aggregations. The resulting statistics will only be accurate if the variable being concorded is spatially distributed in the same way as the population is distributed across the SLA. Each SLA, made up of whole Census Collection Districts (CDs), is an approximation of Australia Post Postcodes with the same four digit code.

The concordance is population weighted and expresses the percentage of the "From" area's population contained within the "To" area. In other words, it expresses the percentage of a SLA's total population contained within an POA that intersects it. Thus, if a SLA is wholly contained within one POA, its total population is also within that POA, and is expressed as 100%. If a SLA is intersected by two or more POAs, then each POA will display the percentage of the SLA population which it contains.

This concordance should not be used to allocate individuals to an POA unless the population percentage is 100%. For example, if it is known that an individual lives in a SLA, but 60% of the population of the SLA lie within one POA and 40% within another, that individual cannot be accurately allocated to an POA without additional information about their location.

File Name

CP2006POA_2006SLA.txt

The file naming convention is:

CharacterMeaning
1“C” for Concordance
2“P” for Population Based Concordance
3-6Year of "To Area"
7-9* Type of "To Area" eg. “POA”
10“_”
11-14Year of "From Area"
15-17* Type of "From Area" eg. “SLA”

* The "From Area" and "To Area" naming convention is mathematically based

For Example:
To POA = From SLA multiplied by population ratio
"2541"="115076951","Shoalhaven (C) - Pt A" * 0.764907
"2540"="115076951","Shoalhaven (C) - Pt A" * 0.235093

This means that SLA 115076951 is split across two POAs. 76.49% of the population of SLA "115076951" is within the POA "2541", and 23.51% of the population of SLA "115076951" is within the POA "2540".

File Format

This concordance is a comma-delimited text file. All 1,426 SLAs and 2,515 POAs current for Census Geographic Areas 2006 are represented.

Field NameTypeComment
POA_2006_CodeCharacterPOA Code 2006
POA_2006_NameCharacterthe same as POA Code 2006
SLA_2006_CodeCharacter*4 digit, ASGC Main Structure SLA code 2006
SLA_2006_NameCharacterSLA Name 2006
RatioNumber**Ratio of total SLA population in a particular POA
PercentNumberPercentage of total SLA population in a particular POA


* For unique Australia-wide identification the SLA code is preceded by the unique first digit State code.
** Ratio - figures expressed as part of 1 - actual figures can be up to 10 decimal places and are expressed in mathematical terms (eg. 4.77810788750317e-04 which is 0.000477810788750317).

Methodology

Each SLA is made up of whole Census Collection Districts (CDs). A CD is the smallest geographical unit used for the collection and dissemination of Population Census data. CDs aggregate to form SLAs. Each CD was allocated a POA code for the 2006 Census of Population and Housing. A POA is an approximation of the Australia Post Postcode with the same four digit code. POAs are made up of whole Census Collection Districts (CDs). CDs and thus POAs cover the whole of geographic Australia without gaps or overlaps.

The percentage population was calculated by summing the populations of the CDs within a SLA and with a particular POA code, and expressing this as a percentage of the SLA's total population.

The population ratio was calculated by summing the populations of the CDs within a SLA and with a particular POA code, and expressing this as a ratio of the SLA's total population.


For enquires please contact the ABS Geography Section, see details below.
_______________________________________________________
ABS Geography Section
Email: geography@abs.gov.au

July 2007