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QUALITY DECLARATION - SUMMARY
Prior to the annual release of Migration, Australia(cat.no. 3412.0) preliminary NOM and NIM data are published quarterly in Australia Demographic Statistics(cat. no. 3101.0). It is made available five to six months after the end of each reference quarter.
Commencing with data for September quarter 2006, final estimates for NOM will be released annually and made available 21 months after the end of the reference period for the previous financial year. In the case of NOM, final data are based on actual traveller behaviour.
Final estimates for NIM and overseas-born residents are made available every 5 years after a Census and revisions are made to the previous intercensal period. Estimates are not changed once they have been finalised.
All migration data sources are subject to non-sampling error which can arise from inaccuracies in collecting, recording and processing the data. The ABS does not have control over any non-sampling error associated with data from DIAC, Medicare Australia and the Department of Defence.
Another dimension of non-sampling error is the fact that the measures of migration estimates become more accurate as more time elapses after the reference period. The trade-off between timeliness and accuracy means that a user can access more accurate data by using the revised or final data.
In recognition of the inherent inaccuracy involved in estimating migration, figures in text published by the ABS are rounded. While unrounded figures are provided in the detailed spreadsheets, accuracy to the last digit is not claimed and should not be assumed. All calculations are based on unrounded numbers.
Annual migration estimates for Australia are available from 1860 onwards. Australia's population by country of birth is available for various states for Census years since 1846 (eg: New South Wales) refer to Australian Historical Population Statistics (cat. no. 3105.0.65.001).
Migration estimates are used in calculating official population estimates. The concept of estimated resident population was introduced in 1981 and backdated to 1971 as Australia's official measure of population based on place of usual residence. Before the introduction of ERP, the Australian population was based on unadjusted census counts on actual location basis. It is important to note this break in time series when comparing historical migration estimates.
An improved method for calculating net overseas migration (NOM) was applied and have been used in compiling Australia's official population estimates from September quarter 2006 onwards. The key change is the introduction of a '12/16 month rule' for measuring a person's residency in Australia replacing the '12/12 month rule'. This change results in a break in time series therefore it is not advised that NOM data calculated using the new method is compared to data previous to this.
The Migration, Australia (cat. no. 3412.0) publication contains detailed Explanatory Notes, Technical Note and Glossary that provide information on the data. More in depth information is available from a number of sources, they include:
Migration data is available free of change in a variety of formats on the ABS website.
The most timely data for both NOM data and NIM data are available quarterly in Australia Demographic Statistics (cat. no. 3101.0).This includes the release of a PDF version of the publication; time series spreadsheets (Excel format) including both NOM & NIM data; and a data cube (Supertable format) with quarterly interstate arrivals and departures data.
The Migration, Australia (cat. no. 3412.0) publication provides annual data and analysis and includes information on overseas-born residents at 30 June each year. This includes the release of a PDF version of the publication; and five time series spreadsheets (Excel format).
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