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Queensland Government population projections: Frequently asked questions

 

Why are three projection series (low, medium, high) produced?

Past and current trends provide background to the possible future of fertility, mortality and migration, but the demographic future is still largely uncertain.

To account for this uncertainty, a range of possible outcomes rather than a single projection series provides a more realistic view of the possible future size, distribution and age structure of Queensland’s population.

Why are different population projection models used for different geographical levels in Queensland?

Queensland’s state and sub-state population projections were generated in sequential stages, using several different models.  The choice of methodology and techniques applied for different geographical areas considered issues such as assumptions about the components of population change (fertility and mortality rates, and overseas and internal migration), the principal determinants of population change (demand for housing versus supply of dwellings), data reliability and availability, the rate of population change, and a region’s share of overall state population.

The future size, distribution and age structure of the populations of Queensland and regions will be the outcome of future levels of fertility, mortality and migration. As such, a demographic cohort component model (incorporating assumptions about future levels of these components of population change) is used to model these populations.

Future population change for smaller geographical levels, such as local government areas and statistical areas level 2, are less likely to be a result of demographic factors alone.

Population change in small geographical urban areas is more a function of available land supply and constraints, and consequent dwelling construction. For example, large amounts of available land supply are expected to result in significant future population growth in areas such as Ripley, Jimboomba (Yarrabilba) and Greenbank (Greater Flagstone).  Constraints on land availability for future dwelling construction are projected to result in slowing population growth in areas such as Noosa.

A housing unit model (HUM) has been used to project the populations in these urban areas.  With the HUM approach, the projected population in urban geographical areas is distributed using anticipated future supply of dwellings (i.e. existing housing stock plus projected new dwellings) and assumptions about future occupancy rates.

In contrast, trend-based models have been used for small rural areas where land supply availability and constraints are not the main drivers of future population change.  Many of these areas are in the resource–rich parts of the state and, as such, have been further adjusted for expected future impacts from construction and operational workforces.

The Australian Bureau of Statistics publishes population projections for Queensland. Why does the Queensland Government also publish projections for Queensland?

The ABS publishes projections at the Queensland state level, as well as for Brisbane Capital City and remainder of state. However, there is a significant need within the Queensland Government and general community for detailed population projections for smaller geographical regions, including local government areas and statistical areas. These are produced by the Queensland Government.

Further, the Queensland Government collaborates with local government strategic planners to ensure that the most up-to-date and accurate land supply information from local government planning schemes is incorporated into the projections for small urban areas.

Why are the 2018 edition projections different from the 2015 edition?

The 2015 edition projections were based on data from the 2011 Census of Population and Housing and demographic information available in 2015. Historical trends, combined with more recent information, show that assumptions around future fertility, life expectancy and overseas migration in Queensland have moderated since the release of the 2015 edition, while there are assumed improvements in interstate migration. As a result, the 2018 edition projections show a slightly smaller population for Queensland over the projection horizon relative to the 2015 edition, with 9.0 million persons by 2061 in the 2018 edition medium series compared with 9.6 million in the 2015 edition.

The 2018 edition also incorporates information from local government councils, many of which have produced updated planning schemes in the period since 2015. Some local government authorities made significant changes to planning schemes, contributing to considerable changes in projections for these areas in the 2018 edition compared with the 2015 edition.

Moreover, this 2018 edition also incorporates information on estimated dwelling yields in Priority Development Areas (PDAs), formerly known as Urban Development Areas, in the Greater Brisbane geographical region. PDAs are parcels of land within Queensland that have been identified for specific accelerated development with a focus on economic growth. Data on PDAs were provided by Economic Development Queensland.

Why are sub-state areas only projected to 2041, while Queensland is projected to 2066?

Future population change in sub-state areas is much more uncertain, and therefore more difficult to predict, than at the state level. As a consequence, while projections have been produced at the state level with a 50–year time horizon to 2066, projections below the state level have been developed with a 25–year time horizon to 2041.

State-level projections are based on assumptions about future levels of fertility, mortality and migration. Trends in a number of these components may be relatively stable in the short term but there is an increasing level of uncertainty over the longer term. While projections have been produced for Queensland to 2066, these simply represent the outcomes should a specific set of assumptions hold true. It is recommended that the three projections series (low, medium, high) be used, as the range between these series provide a more realistic view of possible demographic futures.

Population change in sub-state areas is more likely to be a function of available land supply and constraints, and consequent dwelling construction, than pure demographic factors alone. For example, the population in small areas may suddenly increase after a long period of stability or decline, due to increased land supply; or population growth may slow rapidly in an area due to land supply constraints. The spatial and temporal distribution of land supply arises from regional planning schemes and planning policies and is therefore subject to change. The rate at which the available land supply is used is contingent upon economic conditions and decisions made by the business community. In addition, many planning schemes have 20–25 year horizons and, as such, there is often no information on expected small area spatial development patterns beyond this time frame.

Return to Queensland Government population projections report.

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