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Temporary migration has become increasingly important with more international students, business entrants, working holiday makers and other long-term visitors staying in Australia for periods up to four years or more. Over recent years, there has also been a continued increase of temporary entrants applying for permanent residence or other visas whilst onshore. These changing patterns in traveller behaviour over time have created challenges for the Australian Bureau of Statistics (ABS) in accurately measuring Australia's net overseas migration. In response to this challenge, the ABS made improvements to methodology and processing systems to more accurately capture these changes, and ultimately to improve the quality of NOM estimation. The Australian Department of Immigration and Citizenship's ability to capture and process all traveller information combined with the ABS's improved methodology and additional processing, has placed Australia's measurement of NOM amongst the world's best practice.
Change in methods to improve NOM estimation
Introduction of the 12/16 month rule for estimating NOM
In 2007, to better measure the changes in traveller behaviour and in particular, to more accurately capture and measure temporary migration, the ABS introduced improved methods for calculating NOM. The key improvement was the introduction of the '12/16 month rule', whereby a traveller is included in the resident population if they are in Australia for a total of 12 months or more over a 16 month period, or conversely, subtracted from the population if they are away for a total of 12 months or more over a 16 month period. This has replaced the previous method (12/12 month rule) where a traveller had to be in, or away from, Australia for 12 continuous months.
The current methodology (12/16 month rule) has been calculated from December quarter 2003 to test systems and for quality assurance purposes. This was undertaken before the official release of these new NOM data from the 1 July 2006 when it was used in producing Australia's official estimated resident population (ERP) figures. Prior to this date, the previous methodology (12/12 month rule) had been used to produce the official ERP figures. The change in method has therefore resulted in a break in the official NOM time series at 30 June 2006. For further information on the '12/16 month rule' and the '12/12 month rule' refer to the Glossary and paragraphs 28 to 45 of the Explanatory Notes.
Analysis undertaken by the ABS comparing the previous method (12/12 month rule) to the current method (12/16 month rule) over a three year period (December quarter 2003 to September quarter 2006), shows the current method estimate to be on average 25% higher than the previous estimate. Additional information on the current methodology (12/16 month rule) and the reasons for the change in method can be found under the Explanatory Notes tab, available with the electronic release of the Migration, Australia 2008-09 publication in the Technical Note - '12/16 month rule' Methodology for Calculating Net Overseas Migration from September quarter 2006 and onwards.
Enhancements to Preliminary NOM Estimation
In 2009, the methodology used for preliminary NOM was improved. For further information see Information Paper: Improving Net Overseas Migration Estimation, Mar 2010 (cat. no. 3412.0.55.001).