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Changing the Methodology for Measuring the Impact of Introducing a New Industry Classification for Sub-annual Surveys
Much of the information from these changes will not be available on survey frames until late 2008 or early 2009. As a result, sub-annual collections will now generally be measuring the statistical impact of all these changes using a parallel run methodology, i.e. for (at least) one quarter, generally the June quarter of 2009, a parallel sample will be selected from a frame stratified on the new basis. Data will be required from more businesses under the parallel run methodology than under the parallel estimation methodology, albeit for fewer reference periods, as data will need to be collected from both the old sample based on ANZSIC93 and the new sample based on ANZSIC06, updated benchmarks, SISCA etc. Two sets of estimates will be produced, one on each basis, with the impact of the changes being the difference.
The new parallel run strategy will be more effective than parallel estimation at being able to capture impacts on the level of estimates due to all the changes, including effects from a substantial sample rotation which will occur as a result of redesigned samples. A weakness of the new strategy is the reduced parallel period, which means any changes to seasonality of estimates will be very difficult to determine. We are exploring an alternative 'modelling' strategy using different data sources such as estimates from the completely enumerated sector of samples and taxation data from Business Activity Statements, and will establish an appropriate methodology to assess changes in seasonality.
Survey areas affected by the change are now in the process of updating their plans to take account of the new strategy, with particular focus on ensuring systems and processes are ready to cope with the parallel run, as well as developing plans to quality assure the parallel processes and outputs.
For more information please contact Justin Farrow on (02) 6252 5795 or Paul Schubert on (02) 6252 6591.
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