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Natural increase: births and deaths
8 Natural increase is a major component of ABS quarterly state and territory population estimates and is calculated using the estimated number of births and deaths. The births and deaths data in this release are shown by state and territory of usual residence, using year/quarter of registration for preliminary data and year/quarter of occurrence for both revised and final data. This may affect time series comparisons within relevant tables.
9 The timeliness and accuracy of ABS quarterly population estimates depend in part on the timeliness and accuracy of estimates of births and deaths which are based on registrations. To provide timely estimates, the ABS produces preliminary estimates using births and deaths by quarter of registration as a proxy for quarter of occurrence. For revised estimates, a factor has been applied to the number of occurrences to allow for those occurrences which were yet to be registered at the time of revision. The major difficulty in this area is that while the vast majority of births and deaths are registered promptly, a small proportion of registrations are delayed for months or even years.
10 Preliminary birth and death estimates are subject to fluctuations caused by lags or accumulations in the reporting of births and deaths registrations. Accumulations can result from the eventual processing of lagged registrations in a later quarter. As a result, preliminary quarterly estimates can be an underestimate or an overestimate of the true numbers of births and deaths occurring in a reference period. Lags or accumulations in births and deaths registrations can be caused by:
11 Birth and death registration data contributing to preliminary estimates which are higher or lower than usual are noted below along with any explanations provided by the relevant state or territory registrars:
12 For the purposes of NOM, and thereby Australia's official ERP, a person is regarded as a usual resident if they have been (or expect to be) residing in Australia for a period of 12 months or more. This 12-month period does not have to be continuous and is measured over a 16-month period.
13 The ABS introduced the 12/16 month rule for calculating NOM in September quarter 2006. Consequently this point marks a break in series and NOM estimates from earlier periods are not comparable. For further information on the 12/16 month rule see the Technical Note: '12/16 month rule' Methodology for Calculating Net Overseas Migration from September quarter 2006 onwards in Migration, Australia, 2008-09 (cat. no. 3412.0).
14 Preliminary estimates of NOM are required within six months after the reference quarter for the production of quarterly estimates of the population of Australia, and the states and territories. At that time, complete traveller histories for the 16 months following a reference quarter cannot be produced. Since September quarter 2008, migration adjustments have been applied based on changes between intended and actual duration of stay from final NOM estimates one year earlier for travellers with similar characteristics. These characteristics include their 'initial category of travel', age, country of citizenship, and state/territory of usual/intended residence. The adjustments account for differences between their intended duration of stay and their actual duration of stay.
15 It is with final NOM estimates that the 12/16 month rule can be fully applied. A traveller's actual duration of stay can only be calculated when data on overseas movements become available for the 16 months following a reference period. Final NOM estimation methods use a traveller's actual duration of stay in or out of Australia to determine inclusion or exclusion from NOM estimates and consequently ERP.
16 In an initiative to create a more efficient and streamlined process for travellers departing Australia, the requirement for international travellers to complete an outgoing passenger card was removed by the Department of Home Affairs from 1 July 2017. Due to the removal of the card the ABS has reviewed its net overseas migration (NOM) statistics, methodology and processing systems. Historical NOM data from September quarter 2011 onwards has been produced based on the new methods and has been used in the 2011-2016 intercensal period as part of the final rebasing of population estimates. As NOM estimates cannot be finalised until 16 months after the reference period, NOM is subject to revision. Testing has shown that the revision between preliminary and final NOM using the new methodology has improved when compared to the previous method. For further information see the Information Paper: Improvements to estimation of net overseas migration, Mar 2018 (cat. no. 3412.0.55.004).
17 Statistics on migration and related data are also published regularly by the Department of Home Affairs <http://www.homeaffairs.gov.au>.
18 Australia's ERP and estimates of NOM include all people, regardless of nationality or citizenship, who usually live in Australia, with the exception of foreign diplomatic personnel and their families. Therefore, foreign diplomatic personnel and their families are considered out of scope and were removed from NOM estimates from 1 July 2006. The previous methodology for estimating NOM was unable to exclude diplomatic personnel and their families.
19 Quarterly interstate migration cannot be directly measured and is estimated using administrative data. To do this the ABS uses information on interstate changes of address from Medicare records (produced by the Department of Human Services) and the Department of Defence in the case of the military.
20 The Medicare-based model is calibrated using migration data from the most recent Census (that data is available for), from which updated expansion factors are calculated. Expansion factors account for undercoverage of Medicare data by age and sex. The current model includes the following characteristics:
21 The Medicare system theoretically covers all Australian citizens and permanent residents, as well as temporary visa holders. However, some Australian usual residents do not access the Medicare system, such as temporary migrants or those who have access to other health services. One group is the military. Interstate defence force movements not covered by Medicare are estimated and then added to the Medicare-based interstate movement estimates. Quarterly counts of defence force personnel by age, sex and state/territory, supplied by the Department of Defence, form the number of interstate defence force movements, and 70% are assumed to be not covered by the Medicare-based estimates.
22 Preliminary interstate migration estimates for Other Territories are not available. These movements are included in the data for New South Wales (Jervis Bay Territory and Norfolk Island) and Western Australia (Christmas Island and Cocos (Keeling) Islands). Revised interstate migration estimates will become available following the 2021 Census.
23 For further information see Australian Demographic Statistics, December quarter 2017 (cat. no. 3101.0) Technical Note 2: 2016 Census update of the net interstate migration model.
24 Population projections presented in this release are not predictions or forecasts. They are an assessment of what would happen to Australia's population if the assumed levels of components of population change - births, deaths and migration - were to hold in the future.
25 The ERP at June 2017 based to the 2016 Census is the base for the projections series. Projections off the 2016 Census based ERP were released on 22 November 2018 in Population Projections, Australia, 2017 (base) to 2066 (cat. no. 3222.0). The three series presented in this release, and their assumptions are as follows:
26 Series A - assumes the total fertility rate (TFR) will reach 1.95 babies per woman by 2027 and then remain constant, life expectancy at birth will experience continued improvement until 2065-66, reaching 87.7 years for males and 89.2 years for females, NOM will increase to 275,000 people per year by 2026-27 and remain constant thereafter, and relatively large net interstate migration gains for some states and territories, corresponding to relatively large losses for other states and territories.
27 Series B - assumes the TFR will remain steady at 1.8 babies per woman to 2027 and then remain constant, life expectancy at birth will experience declining improvement, reaching 83.0 years for males and 86.0 years for females by 2065-66, NOM will increase to 225,000 people per year by 2026-27 and remain constant thereafter, and medium net interstate migration gains for some states and territories, and medium losses for others.
28 Series C - assumes the TFR will decline to 1.65 babies per woman by 2027 and then remain constant, life expectancy at birth will experience declining improvement, reaching 83.0 years for males and 86.0 years for females by 2065-66, NOM will decrease to 175,000 people per year by 2026-27 and then remain constant thereafter, and relatively small net interstate migration gains for some states and territories and small losses for others.
Estimates and projections of the Aboriginal and Torres Strait Islander population
29 The standard approach to population estimation is not possible for determining the population of Aboriginal and Torres Strait Islander Australians. There are two primary reasons for this: the significant volatility in Aboriginal and Torres Strait Islander Census counts between censuses which cannot be attributed to demographic factors (i.e. the difference cannot be fully accounted for by natural increase and migration over the intercensal period); and the quality of data on births, deaths and migration specific to Aboriginal and Torres Strait Islander people. As a result, a method based on the use of life tables and rates of net interstate migration derived from the Census is used to backcast the series. Aboriginal and Torres Strait Islander estimates, based on the 2016 Census are available in Estimates of Aboriginal and Torres Strait Islander Australians, June 2016 (cat. no. 3238.0.55.001). Projections based on the 2016 Census will be released in 2019 in Estimates and Projections, Aboriginal and Torres Strait Islander Australians (cat. no. 3238.0).
30 Three main projection series were produced for the 2011 Census with assumptions as follows:
31 Series A - assumes constant fertility rates; 2% annual increase in paternity rates (where the father of a child is Aboriginal or Torres Strait Islander but the mother is not); life expectancy at birth increasing by 0.5 years per year for males and 0.45 years per year for females, reaching 76.5 years for males and 80.4 years for females by 2026; levels of interstate migration as observed in the 2011 Census; and zero net overseas migration.
32 Series B - assumes an annual decrease of 0.5% in fertility rates; 1% annual increase in paternity rates; life expectancy at birth increasing by 0.3 years per year for males and 0.25 years per year for females, reaching 73.5 years for males and 77.4 years for females by 2026; levels of interstate migration as observed in the 2011 Census; and zero net overseas migration.
33 Series C - assumes an annual decrease of 1.0% in fertility rates; constant paternity rates; life expectancy at birth increasing by 0.2 years per year for males and 0.15 years per year for females, reaching 72.0 years for males and 75.9 years for females by 2026; levels of interstate migration as observed in the 2011 Census; and zero net overseas migration.
34 The ABS uses a propensity method to project numbers of households, families and persons in different living arrangements. The method identifies propensities (proportions) from the Census of Population and Housing for people to belong to different living arrangement types. Trends observed in the propensities over the last four censuses are assumed to continue into the future, and applied to a projected population (see Series B, Population Projections, Australia, 2017 (base) to 2066 (cat. no. 3222.0)). Numbers of households and families are then derived from the projected living arrangements of the population.
35 Data presented in table 17 are not intended as predictions or forecasts, but are illustrations of growth and change in the numbers of households which would occur if the assumptions about future trends in living arrangements were to prevail over the projection period. For more information see Household and Family Projections, Australia, 2016 to 2041 (cat. no. 3236.0). Household projections presented in this release are based on the 2016 Census.
36 The Census and Statistics Act, 1905 provides the authority for the ABS to collect statistical information, and requires that statistical output shall not be published or disseminated in a manner that is likely to enable the identification of a particular person or organisation. This requirement means that the ABS must take care and make assurances that any statistical information about individual respondents cannot be derived from published data.
37 Some techniques used to guard against identification or disclosure of confidential information in statistical tables are suppression of sensitive cells, and random adjustments to cells with very small values. To protect confidentiality within this release, some cell values may have been suppressed and are not available for publication (np) but included in totals where applicable. In these cases, data may not sum to totals due to the confidentialisation of individual cells.
38 In this release, population estimates and their components have sometimes been rounded. Where figures have been rounded, discrepancies may occur between sums of component items and totals.
39 ABS statistics draw extensively on information provided freely by individuals, businesses, governments and other organisations. Their continued cooperation is very much appreciated: without it, the wide range of statistics published in the ABS would not be available. Information received by the ABS is treated in strict confidence as required by the Census and Statistics Act 1905.
Use of population estimates in reporting
40 The ABS provides regular explanatory information to support users in understanding both population trends and methodological changes, but does not comment on the specific use (or otherwise) of official population estimates by other organisations or individuals.
41 Population estimates are used extensively within the Australian community, including in a range of agreements. Although the ABS acknowledges that the official population estimates and changes in these estimates are specifically referenced in various agreements, it neither endorses nor disapproves of the terms of the agreements and decisions made by parties in relation to those agreements. In addition, the ABS does not provide a position on disputes arising from the interpretation of terms of an agreement that reference official population estimates.
Additional statistics available
42 As well as the statistics included in this and related products, the ABS may have other relevant data available on request. Inquiries should be made to the National Information and Referral Service on 1300 135 070.
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