3222.0 - Population Projections, Australia, 2017 (base) - 2066 Quality Declaration 
Latest ISSUE Released at 11:30 AM (CANBERRA TIME) 22/11/2018   
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USER GUIDE FOR POPULATION PROJECTIONS


What are population projections?

Population projections illustrate how the Australian population would change in the future if specific patterns of fertility (births), mortality (deaths) and migration were to occur. These potential scenarios are based on assumptions regarding what could happen, according to recent and long-term demographic trends. As we do not know what will happen in the future, a number of different assumptions are used to illustrate a range of possible outcomes. These outcomes include demographic characteristics such as population level, growth, distribution and composition.

What are population projections used for?

Population projections are used by governments, policy makers, planners, the private sector and others for a range of purposes including planning. They are commonly used to estimate future demand for products, services, infrastructure, energy, water and funding. For example, a high growth area with a young population may require investment in public transport, day care centres and schools. Currently, population projections are important for considering the possible outcomes of an ageing Australian population.

What is the difference between a projection and a forecast?

The ABS’ population projections do not predict or forecast how the population of Australia will look in the future. They do not incorporate any non-demographic factors which influence population change, such as government migration policy, improvements in health treatment or the occurrence of natural disasters. Projections only show how the population of Australia would change if the demographic assumptions made were to eventuate over the projection period. This may or may not happen, so projections illustrate possibilities.

What method does the ABS use to produce population projections?

The ABS uses a method that involves making assumptions about future levels of fertility, mortality, net overseas migration and net interstate migration. These are applied to a starting (or base) population (in this case, Australia’s population as at 30 June 2017), split by sex and single year of age, to obtain a projected population for the following year. The assumptions are then applied to this new (projected) population to obtain a projected population for the next year and so on, through to the end of the projection period.

What period is covered?

The population of Australia as at 30 June 2017 is used as the base for the projection series. The population is then projected for the period 30 June 2018 to 30 June 2066 for Australia, states, territories, capital cities and rest of state/territory regions.

What components of population change are considered in ABS population projections?

Various population growth and demographic information is taken into account in the creation of population projections.

These include:
  • Total and age-specific fertility rates
  • The ratio of males to females
  • Life expectancy at birth
  • Total and age-specific death rates
  • Migration flows internationally and interstate, and
  • Differences in these trends between states, territories, capital cities and rest of state/territory regions.

What assumptions are used and how are they determined?

Assumptions are formulated based on demographic trends over recent decades in Australia and overseas. The ABS also consults various individuals and government department representatives at the national and state/territory level. Three assumptions (higher, medium and lower) are used for fertility, net interstate migration and net overseas migration. Two assumptions (high and medium life expectancy) are used to indicate mortality. A number of projections series assuming a net overseas migration of zero are also included, which illustrates the contribution of migration to the Australian population. Observed differences between states, territories, capital cities and rest of state/territory regions are also incorporated. There are 24 possible combinations of assumptions at a national level and 72 at a state and sub-state level. All of these yield different potential population sizes and structures.

What are series A, B and C?

Future uncertainty, along with the subjective nature of assessing recent trends, means that using a range of possible outcomes rather than a single series gives a more useful view of the possible future size, distribution, growth and age and sex structure of Australia's population. Three projection series (series A, B and C) are often used to provide a useful and accessible range of projections for analysis and discussion.

Graph Image for Historical and projected population, Australia

Source(s): Population Projections, Australia, 2017 (base) - 2066



What changes have ABS made to this series of projections and why?

Following advice from demographic experts, ABS incorporated the following changes to the population projections methods:
  • For this issue, we have limited the projection period to 50 years from the 2016 Census, due to the increased uncertainty in the data the further out it is projected from the base year.
  • A longer time series of historical data has been used to form assumptions of fertility to reduce the impact registration lag for some states and territories. Additionally and for the same reason, births by year of occurrence, adjusted with an estimate of registration lag, has been used in place of births by year of registration to form fertility assumptions.
  • A longer time series of historical data has also been used to form assumptions for net overseas migration and net interstate migration, due to the volatility of these components.
  • Similarly, a longer time series of historical data has been used to calculate the state and territory splits of each component.


Why do projection series differ over time?

As we do not know what will happen in the future, population projections are built on assumptions based on demographic trends at the time. The projections can not forecast any unexpected changes to the components that may have a large impact on the size of the population. Recently, the ABS population clock reached 25 million people which led to some media questioning the accuracy of previous Government population projections. The table below shows a comparison of the medium level assumptions over the previous five series of ABS population projections. The most volatile component of population projections is overseas migration. The earlier projections (i.e. those based prior to the shift in net overseas migration in 2006-07) were based on migration policy at the time with an assumptions of around 100,000 migrants per annum. Subsequent changes to migration policy and outcomes led to an increase in assumed migration to an average of 215,000 for the projected period 2008 - present. More recent projections reflected the impact of this policy change and were subsequently more closely aligned with the actual population growth.


Population Projections, Assumptions - Series B, 2002–2017

Life expectancy at birth
Total fertility rate
Males
Females
Net overseas migration
Net interstate migration
Year Australia was projected to reach 25 million
babies per woman
years
years
persons
persons

Population Projections, 2002 to 2101
1.6
84.2
87.7
100 000
medium flows
2032
Population Projections, 2004 to 2101
1.7
84.9
88.0
110 000
medium flows
2027
Population Projections, 2006 to 2101
1.8
85.0
88.0
180 000
medium flows
2019
Population Projections, 2012 (base) to 2101
1.8
85.2
88.3
240 000
medium flows
2018
Population Projections, 2017 (base) to 2066
1.8
83.0
86.0
225 000
medium flows
N/A



Further information

For more information, please see the release Population Projections, Australia, 2017 (base) to 2066 (cat. no. 3222.0) or visit the ABS website at www.abs.gov.au. The National Information and Referral Service can also be contacted on 1300 135 070.