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EXPLANATORY NOTES


INTRODUCTION

1 This publication contains projections of Australia's population by age and sex for the period 2008 to 2101, and projections of the states, territories and capital cities/balances of state for the period 2008 to 2056. Capital city/balance of state projections were not generated for the Australian Capital Territory.

2 Three main series of projections (Series A, B and C) are presented in this publication. These series have been selected to provide a range, although not the full range, of projections for analysis and discussion.

3 For some states, Series A and C do not depict the highest or lowest population outcomes. Where applicable, other series have been included in commentary.

4 These projections supercede the 2004-based series published in Population Projections, Australia, 2004 to 2101 (cat. no. 3222.0) in November 2005.

5 The projections for Australia include Other Territories, comprising Christmas Island, Cocos (Keeling) Islands and Jervis Bay Territory.


OBJECTIVES

6 The ABS publishes population projections twice every intercensal period to regularly service the needs of users of population projections.

7 The projections are not intended as predictions or forecasts, but are illustrations of growth and change in the population that would occur if assumptions made about future demographic trends were to prevail over the projection period.

8 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.

9 Accordingly, alternative combination of assumptions have been provided in recognition of this uncertainty and to provide users with a range of options.


DEVELOPMENT

10 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 various individuals and government department representatives at the national and state levels are necessary to formulate the various assumptions and to ensure their general relevance for the projection period.

11 Consultation occurred from May to July 2008, following which assumptions for the population projections were finalised. Three assumptions were used for fertility, two assumptions were used for mortality, three assumptions were used for net overseas migration and three assumptions were used for internal migration. In addition, a zero net overseas migration assumption has been included to facilitate analysis of the impact of overseas migration to Australia.


PROJECTION TECHNIQUES

12 There are many techniques which may be used for population projections, such as simple extrapolations, probabilistic methods, broad economic, social and time-series analysis, and detailed component methods.

13 The ABS uses the cohort-component method, which begins with a base population for each sex by single year of age and advances it year by year by applying assumptions regarding future fertility, mortality and migration. This procedure is repeated for each year in the projection period for Australia and each state and territory, as well as each capital city/balance of state in each state and territory. The resulting population projections for each year for the states and territories, by sex and single year of age, are adjusted to sum to the Australian results. Likewise, capital city/balance of state projections are adjusted to sum to their respective state/territory projections.


ASSUMPTIONS

14 Assumptions regarding future levels of fertility, mortality and migration used to produce the population projections, and how they were formulated, are discussed in Chapter 2 - Assumptions.


ACKNOWLEDGMENT

15 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

16 Users may also wish to refer to the following ABS products:

Australian Demographic Statistics (cat. no. 3101.0)
Australian Historical Population Statistics (cat. no. 3105.0.65.001)
Births, Australia (cat. no. 3301.0)
Causes of Death, Australia (cat. no. 3303.0)
Deaths, Australia (cat. no. 3302.0)
Demographic Estimates and Projections: Concepts, Sources and Methods (cat. no. 3228.0)
Experimental Estimates and Projections, Aboriginal and Torres Strait Islander Australians, 1991 to 2009 (cat. no. 3238.0)
Household and Family Projections, Australia, 2001 to 2026 (cat. no. 3236.0)
Information Paper: Improved Methods for Estimating Net Overseas Migration (cat. no. 3107.0.55.003)
Information Paper: Statistical Implications of Improved Methods for Estimating Net Overseas Migration, Australia, 2007 (cat. no. 3107.0.55.005)
Migration, Australia (cat. no. 3412.0)
Population by Age and Sex, Australian States and Territories (cat. no. 3201.0)

• Projected population, Australia, 2006-2101 - in SuperTABLE format;
• Projected population, capital city/balance of state, 2006-2056 - in SuperTABLE format for each state/ territory;
• Projected population, components of change and summary statistics, 2006-2101 - in Microsoft Excel format for Australia, state/territory and capital city/balance of state.