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Queensland Government population projections: Frequently asked questions

 

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

The Queensland Government population projections should not be interpreted as precise point estimate forecasts or predictions. Rather, the projections reflect the outcomes of applying a set of assumptions about the future to a base population. As a result, the accuracy of these projections is dependent on the extent to which the underlying assumptions eventuate.

The population projections are based on trends and assumptions around fertility, mortality and migration, as well as future housing supply and historical population trends. Future levels of fertility, mortality, migration and dwelling stock can be unpredictable, and historical population trends may not continue, which introduces uncertainty into projections of the future population.

To account for uncertainty in these components of population change and housing supply, three projection series (low, medium and high) have been developed to illustrate a range of possible future outcomes.

Each of the low, medium and high series reflects a unique combination of assumptions about demographic components and other factors impacting population change, and is one of many possible scenarios for future population change in Queensland and its sub-state regions.

Users should exercise caution in the interpretation and use of population projections, particularly sub–state level projections where there is a much greater degree of uncertainty. The uncertainty in future population change increases the further from the base year into the future. Users are advised to consider the combination of assumptions underpinning each series when using the population projections, as outlined in the Queensland Government population projections: Methodology and assumptions report.

What geographies are population projections produced for?

The 2023 edition of the Queensland Government population projections includes projections of the usual resident population by age and sex across different geographical levels within Queensland.

Data are released for the following geographical boundaries:

  • the State of Queensland
  • Greater Brisbane Greater Capital City Statistical Area (GCCSA)
  • statistical areas level 4 (SA4)
  • statistical areas level 2 (SA2)
  • local government areas (LGA).

The geographical boundaries are sourced from Edition 3 of the Australian Statistical Geography Standard (ASGS), defined by the Australian Bureau of Statistics. The 2021 version of boundaries for LGAs is used.

The previous (2018) edition of the Queensland Government population projections reflects geographical boundaries from the 2016 edition of the ASGS, which differ from Edition 3 at the SA2 and LGA levels for some regions within Queensland. Maps of individual regions under Edition 3 and the 2016 edition of the ASGS are available under Geographical boundaries on the Queensland Government Statistician’s Office website.

The 2023 edition population projections are available for all of the above listed geographies under the medium series, whereas low and high series population projections are available for the State of Queensland, Greater Brisbane GCCSA and the 10 remaining SA4s, and LGAs.

The 2023 edition uses the preliminary rebased estimated resident population of 2021 as the base population, with projection horizons to 2071 for Queensland and 2046 for sub-state areas.

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

Queensland’s state and sub–state population projections are generated in sequential stages, using several different models. The choice of methodology and techniques applied for different geographical areas and different geographical levels considered issues such as:

  • assumptions about the components of population change (fertility and mortality rates, and overseas, interstate and intrastate migration)
  • the principal determinants of population change (demand for housing versus supply of dwellings)
  • data reliability and availability
  • the rate of population change
  • a region’s share of overall state population.

The principal driver of population change, and suitable ways to model it, varies between different geographical levels and regions. Demographic component assumptions are considered the main drivers of population change and the future size, distribution and age structure of the populations for the State of Queensland, Greater Brisbane Greater Capital City Statistical Area and the 10 remaining statistical areas level 4.

Future population change for lower geographical levels however, such as local government areas (LGA) and statistical areas level 2 (SA2), is not modelled primarily as the result of demographic factors, as it is at higher geographical levels. Instead, population change is considered to be primarily driven by either the future supply of, or demand for, housing:

  • In the case of future housing supply, population change is considered a function of available dwelling supply and occupancy constraints, and anticipated consequent dwelling construction.
  • In the case of future housing demand, population change is informed by population trend–based models that reflect the demand for housing. Additional dwelling supply is not considered the chief limiting factor in population change.

Population projections for each SA2 have been developed using either of the two approaches above. Following this, projections for LGAs are derived from projections at the SA2 or lower geographical level.

For more information about the projection models used to generate projections for different geographical levels, see the Queensland Government population projections: Methodology and assumptions report.

Why are sub-state areas only projected to 2046, while Queensland is projected to 2071?

The uncertainty in future population change increases the further from the base year into the future. Population change in sub-state areas is much more uncertain, and 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 2071, projections at the sub-state level have been developed with a 25–year time horizon to 2046.

A key data source for producing projections is local government planning schemes and datasets. These are used to inform the spatial and temporal distribution of population change at the SA2 level. At the time of production, many local government planning schemes did not extend beyond 2046 and often there is no information on expected small–area spatial development patterns beyond this time frame. Planning schemes and data are subject to future change and review, and may be revised from that used to inform the 2023 edition of the Queensland Government population projections.

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

The Australian Bureau of Statistics and Australian Government Centre for Population publish projections at the Queensland state level, as well as for Greater Brisbane Capital City Statistical Area and the remainder of state. However, there is a significant need within Queensland Government and the general community for detailed population projections for smaller geographical regions, including local government areas and statistical areas. To meet this need, the Queensland Government produces three projections series at the state level, and projections for sub-state regions consistent with these.

Further, the Queensland Government Statistician's Office collaborates with local government strategic planners to ensure that the most up-to-date and accurate dwelling supply information from local government planning schemes is incorporated into the projections at the small-area level, where relevant and possible. Estimated dwelling yields for some Priority Development Areas were also provided by Economic Development Queensland.

To reflect the uncertainty in future population change, a range of scenarios is produced rather than only a single projections series (see FAQ question Why are three projection series (low, medium, high) produced? above). To remain as up-to-date as possible with the latest population outcomes and trends reflected in available data, the Queensland Government traditionally produces three scenarios, twice every five years. This schedule was disrupted due to the magnitude of uncertainty around how the COVID-19 pandemic would impact future population change.

Why are the 2023 edition projections different from the 2018 edition?

The 2023 and 2018 editions reflect different sets of underlying assumptions about future population change within Queensland and its sub-state regions.

The 2018 edition projections were based on data from the Australian Bureau of Statistics 2016 Census of Population and Housing and demographic information available at the time of production in 2018, while the 2023 edition is based on data sourced from the more recent 2021 Census. The 2023 edition also incorporates additional data, including from other sources, published since the 2018 edition was produced. This includes revisions to historical data used in the 2018 edition. The base year of the 2023 edition projections is 2021, while the 2018 edition base year was 2016.

There have been impacts to Queensland’s population size and distribution as a result of the COVID-19 pandemic, which were unforeseen at the time the 2018 edition was produced. See FAQ question Do the 2023 edition projections account for the impacts of the COVID-19 pandemic? below.

Apart from the demographic impacts of the pandemic on current and future population levels, a key difference is that the 2023 edition has a notably lower assumed long–term total fertility rate (TFR). This was informed by a declining Queensland TFR in recent years (similar to the rest of Australia), which has dropped below the long-term level assumed in the 2018 edition medium series. As a result, the 2023 edition projections are lower than in the 2018 edition. In particular, population growth rates in some sub-state areas are projected to be much lower than in previous editions, and some regions are projected to experience population decline for the first time.

The projected spatial and temporal distributions of population change for statistical areas level 2 and local government areas are informed by anticipated dwelling supply from local government planning schemes and datasets. These local government schemes are subject to future change and review, and may have been revised from similar information used to inform the 2018 edition. The rate at which the available dwelling supply is taken up in future is contingent upon economic conditions and decisions made by the business community, and is subject to uncertainty.

The 2023 edition also incorporates information on estimated dwelling yields for some Priority Development Areas (PDAs), formerly known as Urban Development Areas, across Queensland. 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.

Do the 2023 edition projections account for the impacts of the COVID-19 pandemic?

The 2023 edition of the Queensland Government population projections incorporated the most up-to-date and relevant data available at the time of production, and aims to reflect the latest population outcomes and trends in the available data. There was still a considerable level of uncertainty around some future demographic impacts due to the COVID-19 pandemic at the time of production.

The World Health Organization declared the novel coronavirus (COVID-19) a worldwide pandemic on 11 March 2020. The pandemic, as well as associated response measures and restrictions enacted by different levels of government both within Australia and internationally, has impacted population growth in Australia since early 2020. Most restrictions and associated health measures were eased incrementally in Australia during 2022, however some demographic impacts of the COVID-19 pandemic were still apparent at the time of production of the 2023 edition projections. Queensland’s population is expected to be smaller and slightly older than what was anticipated prior to the COVID-19 pandemic.

While past and current trends provide background to the possible demographic outlook for Queensland, there is uncertainty around how these trends will evolve over a 50–year projection horizon for Queensland and a 25–year projection horizon at the sub-state level. For an overview of recent population growth in Queensland, and how this has varied from historical trends since the onset of the COVID-19 pandemic in early 2020, see the Queensland Government population projections Background research paper.

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