Ag Mag | the agriculture newsletter

EXAMPLES OF MAPS OF AGRICULTURAL CENSUS DATA BY MESH BLOCK


Mesh blocks are micro level units of geography recently adopted by the ABS. These new units are small enough to aggregate Agricultural Census data accurately to the wide range of different spatial units used by other organisations. In the past, Statistical Local Area (SLA) was the smallest unit to which agricultural data could be disseminated.

Using address information provided in the 2005-06 Agricultural Census a latitude and longitude were assigned to more than 151,000 farms. Each farm was then allocated to the appropriate mesh block. Examples of how data can be presented at the mesh block level can be seen in the following maps which provide an indication of the extent of dairying and potato growing in Tasmania, based on data from the 2005-06 Agricultural Census.

By way of comparison, a map of dairy cows in Tasmania at the SLA level is also included to highlight the improved clarity the smaller mesh blocks provide over the larger SLA units. Larger images with better definition can be obtained by downloading these linked PDF files (dairy cows 3.7 MB and potato production 3.6 MB).

In interpreting these maps, users need to take into account the limitations of the data and the presentation, including those listed below.

• Estimates at meshblock level are used to assign the range to which each meshblock belongs as a whole. This does not mean that the agricultural activity is evenly spread across the meshblock.
• While the estimates are based on a census, non-response leads to imprecision in the data, which could be reasonably high at meshblock level. Accordingly, not all data are suitable to be presented this way, particularly less significant activities. Meshblock presentations cannot be provided for survey years.
• No indication of of the quality of the data has been provided. The relative standard error (RSE) of the estimate used to determine the range to which each meshblock belongs may not give an accurate reflection of the reliability of the range, and has not been provided.
• Any errors in geo-coding result in imprecision in the geographical distribution of activities. The impact of such errors is not well known.

Dairy cows on agricultural land.





Potato production on agricultural land.