Mesh Blocks
The ABS is currently developing a new geographical unit known as Mesh Blocks that will be four to five times smaller than a Collection District. It is planned that Mesh Blocks will become the basic building block for all statistical, political and administrative regions in Australia.
Currently there are a wide range of geographic units in use in Australia. Many organisations adopt their own geographical units to suit their needs, often without reference to units that are used by others. As a result, data cannot be readily integrated and exchanged between organisations. Incompatible geographical units have hampered the use of statistics and the development of Mesh Blocks will help address this problem.
If statistics are to be compared across collections, across subject matter, and across organisations, then the geographic areas to which the statistics refer must be comparable.
Some regions, such as Electoral Divisions, Postcodes and Suburbs are currently approximated by grouping Collection Districts (CDs) together on a 'best fit' basis. CD derived boundaries, and therefore the full range of 2001 Census data, are available for all these regions. During the CD design process prior to the last census, there was a considerable effort made to align CD boundaries to gazetted suburb boundaries, so generally CD derived suburbs are a very close approximation of official suburbs.
However, the primary role of CDs is census collection and restraints placed upon their boundaries by collection requirements mean that they do not align closely with river catchments, the boundaries of small rural localities, or many administrative regions. CDs must have a physical boundary visible to the collector on the ground, and many natural and administrative boundaries are aligned to less obvious features in the environment or to property boundaries.
While the Collection District will always need to cater for collection requirements, it is now possible to develop a new micro level spatial unit that is not constrained by the functional requirements of census collection. Importantly, data will be coded to Mesh Blocks independent of the census collection methodology, so there will be no need for Mesh Blocks to fit within existing Collection District boundaries.
Mesh Blocks will be so small that they will be able to aggregate reasonably accurately to any geographical region. This will result in more accurate demographic analysis, which in turn will lead to improved government policy formulation and service delivery. The ability to more easily integrate data from different sources will also decrease duplication between organisations.
The Mesh Block concept is only now feasible due to advances in GIS technology and improved access to digital topographic data. In particular, the recent development of the Geocoded National Address File (G-NAF) by PSMA Australia now enables the efficient coding of address information to small geographic units.
It is estimated that Australia would be divided into around 200,000 Mesh Blocks, compared to the 37,209 CDs that are currently the smallest spatial unit. The ABS aims to have Mesh Blocks designed and built in time for the dissemination of data for the 2006 Census. However to meet the planning time frames and risk management procedures of the census, draft Mesh Blocks must be finalised in time for the census Dress Rehearsal in May 2005.
Mesh Blocks will only be introduced with stringent measures to ensure that confidentiality is maintained. The ABS is strongly committed to maintaining confidentiality, and has a legal requirement under the Census and Statistics Act 1905 to ensure that no information is released that may identify an individual. Only a very limited amount of census data will be published for individual Mesh Blocks.
For more information, consult Information Paper: Mesh Blocks (cat. no. 1209.0).
2011 and Beyond
For the 2011 Census, Collection Districts will no longer be an output unit. Instead, they will only be used for the collection phase of the census. For data output, it is proposed that the CD be replaced by a new spatial unit of around the same size that will be specifically designed for output purposes. There will be an extensive user consultation process before any of these changes are implemented
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