Local Government Area from Postal Area 2006 Concordance

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 Local Government Area from Postal Area (LGA from POA) concordance for 2006 allows the conversion of population data from Postal Areas (POA) to Local Government Areas (LGAs). 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 LGAs; 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 LGA 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 LGA that intersects it. Thus, if a POA is wholly contained within one LGA, its total population is also within that LGA, and is expressed as 100%. If a POA is intersected by two or more LGAs, then each LGA will display the percentage of the POA population which it contains.

This concordance should not be used to allocate individuals to an LGA 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 LGA and 40% within another, that individual cannot be accurately allocated to an LGA without additional information about their location.
File Name

CP2006LGA_2006POA.txt

The file naming convention is:

Character	Meaning
1	“C” for Concordance
2	“P” for Population Based Concordance
3-6	Year of "To Area"
7-9	* Type of "To Area" eg. “LGA”
10	“_”
11-14	Year 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 LGA = From POA multiplied by population ratio
"18050","Waverley (A)"="2029" * 0.354483
"18500","Woollahra (A)"="2029" * 0.645517

This means that POA 2029 is split across two LGAs. 35.44% of the population of POA "2029" is within the Waverley (A) LGA, and 64.55% of the population of POA "2029" is within the Woollahra (A) LGA.

File Format

This concordance is a comma-delimited text file. All 2,515 POAs and 676 LGAs plus 9 unincorporated areas current for Census Geographic Areas 2006 are represented.

Field Name	Type	Comment
LGA_2006_Code	Character	*4 digit, ASGC Main Structure LGA code 2006
LGA_2006_Name	Character	LGA Name 2006
POA_2006_Code	Character	POA Code 2006
POA_2006_Name	Character	the same as POA Code 2006
Ratio	Number	**Ratio of total POA population in a particular LGA
Percent	Number	Percentage of total POA population in a particular LGA

* For unique Australia-wide identification the LGA 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 LGAs. 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 LGA 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 LGA code, and expressing this as a ratio of the POA's total population.


Treatment of Unincorporated Areas

The LGA Structure of the ASGC covers only incorporated areas of Australia. Incorporated areas are legally designated areas over which incorporated local governments have responsibility. The major areas of Australia not covered by incorporated bodies are the northern parts of South Australia, most of the Northern Territory, all of the Australian Capital Territory and all of the Other Territories (Jervis Bay Territory, Territory of Christmas Island and Territory of Cocos (Keeling) Islands).

Unincorporated areas are included in this concordance. For each state/territory they are identified as follows:

19399 Unincorporated NSW
29399 Unincorporated Vic
39399 Unincorporated Qld
49399 Unincorporated SA
59399 Unincorporated WA
69399 Unincorporated Tas
79399 Unincorporated NT
89399 Unincorporated ACT
99399 Unincorp. Other Territories

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

July 2007