2905.0.55.001 - ABS Postal Area Concordances, Aug 2006  
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Statistical Local Area from Postal 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 Statistical Local Area from Postal Area (SLA from POA) concordance for 2006 allows the conversion of population data from Postal Areas (POA) to Statistical Local Areas (SLAs). 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 POA to SLA 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 POA. Each POA, 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 POA's total population contained within an SLA that intersects it. Thus, if a POA is wholly contained within one SLA, its total population is also within that SLA, and is expressed as 100%. If a POA is intersected by two or more SLAs, then each SLA will display the percentage of the POA population which it contains.

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

File Name

CP2006SLA_2006POA.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. “SLA”
10“_”
11-14Year of "From Area"
15-17* Type of "From Area" eg. “POA”


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

For Example:
To SLA = From POA multiplied by population ratio
"205650912","Bayside (C) - South"="3190" * 0.711549
"205653431","Kingston (C) - North"="3190" * 0.288451

This means that POA 3190 is split across two SLAs. 71.15% of the population of POA "3190" is within the Bayside (C) - South SLA, and 28.85% of the population of POA "3190" is within the Kingston (C) - North SLA.

File Format

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

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

* 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

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). 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. 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 POA and with a particular SLA code, and expressing this as a percentage of the POA's total population.

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

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

July 2007