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1 This publication contains projections of Australia's population by age and sex for the period 2002–2101 which show the longer term impact of the various components. Projections for the states and territories and capital cities/balances of state cover the period 2002–2051. Capital city/balance of state projections were not generated for the Australian Capital Territory.
2 These series of projections supersede the 1999-based series, published in August 2000, Population Projections, Australia, 1999–2101 (cat. no. 3222.0). Additional unpublished details relating to this series, including population by sex and single years of age, can be obtained by contacting the National Information and Referral Service.
3 The projections for Australia include Christmas Island, Cocos (Keeling) Islands and Jervis Bay Territory. Jervis Bay Territory is excluded from projections for the Australian Capital Territory.
4 The ABS currently publishes population projections every two to three years in order to regularly service the needs of users of population projections.
5 The projection results published by the ABS are not intended as predictions or forecasts, but are illustrations of growth and change in the population which would occur if the assumptions about future demographic trends prevail over the projection period.
6 While the assumptions for the projections are formulated on the basis of an assessment of past demographic trends, both in Australia and overseas, there is no certainty that any of the assumptions will or will not be realised. In addition, no assessment has been made of changes in non-demographic conditions.
7 Accordingly, alternative projections have been provided in recognition of this uncertainty and to provide users with a range of options.
8 The process of developing population projections involves research, analysis, consultation and computation. Analysis of demographic trends, research into the determinants of population growth and distribution, and consultation with government at both national and state levels are necessary to formulate the various assumptions and to ensure their general relevance for the projection period.
9 Consultation occurred from November 2002 to April 2003, following which the assumptions for the 2002–2101 series of population projections were finalised. For fertility three assumptions were selected. Two assumptions were used for mortality, and three assumptions were used for both overseas migration and internal migration.
10 There are many techniques which may be used for population projections, ranging from simple extrapolations through broad economic, social and time-series analysis to detailed component methods. The ABS uses the cohort-component method, which begins with a base population for each sex by single years of age and advances it year by year by applying assumptions regarding future fertility, mortality and migration. Assumed age-specific fertility rates are applied to the female population of child-bearing ages to provide the new cohort of births. This procedure is repeated for each year in the projection period for each state and territory and for Australia. It is also repeated to obtain capital city/balance of state projections for each state and territory. The resulting population projections for each year for the states and territories, by sex and single years of age are adjusted to sum to the Australian results. Likewise, capital city/balance of state projections are adjusted to add exactly to the state/territory projections.
11 Total fertility rates for capital cities and balances of states for the years 2002–2011 were calculated by applying the assumed total fertility differential to the assumed total fertility rates for Australia.
12 Age-specific fertility rates for capital cities and balances of states were calculated by applying fertility differentials for each single year of age to the assumed age-specific fertility rate for Australia for each year in the projection period. Fertility differentials for capital cities and balances of states were derived using the average differential of the years 1999–2001.
13 Projected life expectancy at birth was based on the trend in life expectancy at birth between 1971 and 2001. The medium assumption has the 1999–2001 male and female life expectancies projected to increase by 0.30 and 0.25 years respectively, each year until 2005–06, thereafter life expectancy was assumed to increase at a diminishing rate to 2050–51. The high assumption assumes annual improvement in life expectancy at birth will remain constant at 0.30 and 0.25 years for males and females respectively to 2050–51.
14 The pattern of decline in age-sex-specific death rates from 1970–1972 to 1999–2001 was assumed to continue, within the constraints of the predetermined levels of life expectancy at birth. Where there was an upward trend in age-sex-specific death rates, some limitations were applied to prevent an increase in assumed future mortality rates for particular ages.
15 The long- and short-term differentials in life expectancy between each state and territory and capital city/balance of state have been maintained throughout the projection period.
16 Historical trends were used to project net interstate and net overseas migration by capital city/balance of state. Net migration to each capital city and balance of state/territory was assumed to be the difference between population growth and natural increase in these regions, constrained to state/territory levels
17 Final category jumping for the period September quarter 1997 to June Quarter 2001 have been set to zero. Preliminary category jumping September Quarter 2001 to December Quarter 2002 has also been set to zero but will be revised when additional information becomes available. This was necessitated by the recent detection of a deficiency in the current measurement of migration category jumping. For further information see Demography Working Paper 2003/1—Estimated Resident Population and Measurement of Category Jumping. Therefore, the lack of reliable category jumping estimates in recent years has led to an assumption for category jumping of zero for the projection Series.
18 Annual overseas migration to each state and territory was divided between the capital city, and the balance of the relevant state based on the proportion of recent arrivals and departures recorded in the 1996 and 2001 Censuses.
19 The assumed age-sex structure of each overseas migration component for each state and territory was based on the average structure from 2001–02. Age-sex profiles at the capital city/balance of state level were derived from the 1996 and 2001 Census questions on residence one and five year(s) ago.
20 Net internal migration to each capital city and balance of state was assumed to be the difference between net total migration and net overseas migration, constrained to respective state/territory migration estimates.
21 Assumed age-sex profiles of future interstate flows were derived from 1991, 1996 and 2001 Census arrival and departure rates. Three Censuses were used to get sufficient numbers for reliable rates, with the more recent data weighted more heavily. Departure rates are out-migrants as a proportion of the donating state/territory's population. Arrival rates are in-migrants as a proportion of all other State/Territory's population. For capital city/balance of state annual profiles, age/sex levels were used rather than arrival rates which tend to suffer from extreme denominators.
22 ABS publications 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 by 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.
RELATED PUBLICATION AND REFERENCES
23 Users may also wish to refer to the following ABS electronic data and publications:
AusStats - electronic data
Australian Demographic Statistics (cat. no. 3101.0) - issued quarterly
Australian Demographic Trends (cat. no. 3102.0) - issued irregularly
Births, Australia (cat. no. 3301.0) - issued annually
Causes of Death, Australia (cat. no. 3303.0) - issued annually
Deaths, Australia (cat. no. 3302.0) - issued annually
Experimental Projections of the Aboriginal and Torres Strait Islander Population (cat. no. 3231.0) - issued irregularly
Household and Family Projections, Australia, 1996 to 2021 (cat. no. 3236.0) - issued irregularly
Migration, Australia (cat. no. 3412.0) - issued annually
Overseas Arrivals and Departures, Australia (cat. no. 3401.0) - issued monthly
Population by Age and Sex, Australian States and Territories (cat. no. 3201.0) - issued annually.
24 Current publications and other products released by the ABS are listed in the Catalogue of Publications and Products (cat. no. 1101.0). The Catalogue is available from any ABS office. The ABS also issues a daily Release Advice on the web site which details products to be released in the week ahead.
25 As well as the statistics included in this and related publications, additional information is available from the ABS web site at www.abs.gov.au and accessing Themes/Demography.
SYMBOLS AND OTHER USAGES
ABS Australian Bureau of Statistics
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