The Estimated areas are based on data collected from the 2003 Survey of Disability, Ageing and Carers, and the 2001 Census. In early 2006, a series of workshops were conducted for National Disability Administrators (NDA) constituents to explain the quality and limitations of the small area estimates of disability released as an ABS consultancy.  The workshop material and explanatory notes contained a series of diagnostic measures and broad assessments of the quality of the small area output. Arguably the most important measure of the quality discussed at the workshops was the relative root mean square error (RRMSE), which represent the associated model error in predicting each small area estimate.  The method for calculating the original RRMSEs excluded some components of total error that were subsequently shown to be sizeable.  Recently an improved, though more computationally sophisticated method, was used to revise the RRMSEs.  In the case of the disability estimates, the revised RRMSEs are up to 4 times larger than the original RRMSEs.

Example - Revised RRMSE for Melbourne City

Table 2 of Release 2 showed that the LGA estimate of the proportion of children aged 4-9 years old with a disability in Melbourne city was 0.09 or 9%.  The corresponding original RRMSE for this estimate was 7.4%. This can be interpreted to mean that are 19 chances in 20 (or 95%) that the true, unknown value of this estimate of 9%, will fall between 7.7% and 10.4%. table missing here The revised RRMSE for the proportion of children aged 4-9 years old with a disability in Melbourne City increases to 30.8%. This means that a more reliable indication of the quality of this estimate is that there are 19 chances in 20 that the true proportion actually lies in the range 4.8% and 16.1%. The wider confidence interval reflects the increased uncertainty about the true value of the proportion.

Small Area Estimates by Jurisdiction:

• ACT - Under construction
• NSW Small Area Estimates
• Northern Territory - Not available
• Queensland - Under construction
• South Australia Small Area Estimates
• Tasmania Small Area Estimates
• Victoria Small Area Estimates
• Western Australia Small Area Estimates

For more information please contact your State or Territory Member Jurisdiction.