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FEATURE ARTICLE: REBASING OF AUSTRALIA'S POPULATION ESTIMATES USING THE 2016 CENSUS
3. Backdating from Census night to 30 June
The third step backdates the ERP at Census night (9 August 2016) to the ERP at 30 June 2016 by;
The steps are illustrated in the following diagram:
The table below shows how the ABS arrived at 30 June ERP for Australia, states and territories after applying the adjustments above.
ADJUSTING FOR NET UNDERCOUNT
Adding the net undercount (undercount minus overcount) of people back into the population is a crucial step in arriving at the most accurate ERP possible. Net undercount is the difference between the actual Census count and the estimate of the number of people who should have been counted in the Census. It is the result of Census undercount, overcount, differences in classification between the PES and Census, and imputation error.
The 2016 PES estimate of net undercount for Australia in the 2016 Census was 226,400 people (including additional minor coherence and quality adjustments). For more information on the PES see Census of Population and Housing: Details of Overcount and Undercount, Australia (cat. no. 2940.0) and Information Paper: Measuring Overcount and Undercount in the 2016 Population Census (cat. no. 2940.0.55.002).
RESIDENTS TEMPORARILY OVERSEAS
Residents temporarily overseas (RTOs) during the Census are those who were outside Australia for less than 12 months over a 16-month period, and therefore are added to the ERP. A departing resident is excluded from Australia's resident population only when they leave Australia for 12 months or more over a 16-month period. The preliminary estimate of RTOs on 2016 Census night was 632,700 people. The preliminary estimate models the duration of overseas stay of departing residents. The final estimate of RTOs will be calculated when data for actual arrivals and departures up to 16 months after Census are available, and will be included in the final rebased ERP.
Demographic adjustments are a range of small adjustments made to the population at the national level. These adjustments ensure coherency with previous population estimates and address known issues, such as age misreporting in the centenarian population. Detail on these demographic adjustments will be provided in the forthcoming Information Paper: Ensuring the Quality of Rebased Population Estimates, 2016 (cat. no. 3250.0); to be released 28 July 2017.
Intercensal difference is the difference between new Census-based ERP for 30 June of the Census year and the ERP for the same point in time carried forward from the previous Census base using births, deaths and migration data.
Intercensal difference can be attributed to one or more of three sources;
The table below shows the preliminary intercensal difference by number and percentage of total population for 2011 to 2016 for Australia, states and territories.
Information collected in the 2016 Census will also allow the ABS to estimate how much of the preliminary intercensal difference is due to inaccuracies in estimates of interstate migration. To do this, the ABS will analyse data from the Census questions about place of usual residence one and five years ago. These results will be released in the December 2017 issue of this publication (released in June 2018).
After the preliminary intercensal difference is adjusted for revisions to the components of population change (births, deaths and migration), the remaining (un-attributable) portion is referred to as the final intercensal difference. The intercensal difference for each state and territory, birth cohort and sex are spread evenly across the intercensal quarters. Thus the intercensal difference acts as a balancing item, that when combined with births, deaths and migration equals the difference between the two Census-based population estimates. The final intercensal difference cannot be attributed to a particular source.
FURTHER DATA RELEASES
Final population estimates based on the 2016 Census for Australia, states and territories, for 30 September 2011 to 30 June 2016, will be published in the December quarter 2017 issue of Australian Demographic Statistics (cat. no. 3101.0) to be released in June 2018. No subsequent revisions are planned to be made to the final rebased estimates.
Preliminary rebased estimates for SA2s and LGAs will be published in a special issue of Regional Population Growth, Australia (cat. no. 3218.0) to be released on 28 July 2017. Final rebased sub-state estimates will be released by August 2018.
Preliminary rebased estimates of the Australian Aboriginal and Torres Strait Islander population by age, sex and state/territory at 30 June 2016 will be published in the March quarter 2017 issue of Australian Demographic Statistics to be released on 28 September 2017. Further disaggregation of these estimates will be released in August 2018.
Further detail on the 2016 Census rebasing of Australia's population estimates will be published in Information Paper: Ensuring the Quality of Rebased Population Estimates, 2016 (cat. no. 3250.0) to be released on 28 July 2017.
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