Mesh Blocks
Across its statistical collections, the ABS uses a common standard for geographical areas known as the Australian Standard Geographical Classification (ASGC). The smallest building block currently in use for statistical data collection is the Census Collection District (CD), typically comprising 100 to 220 households. CDs are, however, subject to certain constraints, consequently they do not always align to desired geographic regions.
One method of avoiding this shortcoming is through the use of geocoding, a process of allocating latitude and longitude to each individual dwelling or business, thereby describing its position on the surface of the earth. Once a statistical unit has been geocoded it is a relatively simple process to code it to any geographical classification simply by ‘overlaying’ the geocoded point with a set of regions in a Geographical Information System (GIS).
Geocoding of individual households, however, has the potential to create public concern about confidentiality. To obtain most of the advantages of geocoding without compromising confidentiality the ABS proposes to develop a new micro-level geographical unit known as a Mesh Block. Mesh Blocks will on average contain 20 to 50 households and could be created to align with the widest range of administrative and natural boundaries. Only very basic census data would be available at the Mesh Block level, perhaps only number of dwellings and population counts, but the full range of census data would be available for combinations of Mesh Blocks. If statistical and administrative geographies are to share a common building block then Mesh Blocks must be implemented in a manner that is more consistent and precise than statistical application alone would require.
It is vital that state governments fully participate in the consultation process and inform the ABS on how to define Mesh Blocks in a way that would be consistent with state use for statistics but also for local authority boundaries, geographical names, electoral purposes,and so on. Once designed and readily available, Mesh Blocks have the potential to become a new building block of Australian geography so that any organisation developing a set of regions would build up its areas simply by adding Mesh Blocks together in whatever combination best suited its purpose. This in turn would ensure that census data could be accurately derived for those regions.
There will always be a need to define different sets of geographical areas for different purposes — one size will never fit everyone. It is possible, however, for different geographies to share a common building block and thereby achieve a level of comparability and compatibility far beyond what we have today. A panel of experts is currently advising the ABS on ideal design parameters for Mesh Blocks and an ABS position paper will be published in February 2004, followed by an intensive consultation with States and other key stakeholders in March/April 2004.
For further information, contact Frank Blanchfield by ( (02) 6252 7759 or email: frank.blanchfield@abs.gov.au
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