Census methodology

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Information on data quality, processing and collection

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As Australia’s largest statistical collection, the information provided in the Census helps estimate Australia’s population, is used to set electoral boundaries, underpins the distribution of billions of dollars in public funding and informs planning for services and infrastructure for every community in Australia.

To assist in interpreting data released from the Census, the ABS provides information about how we collect and process Census data, as well as important information about the data quality.

Key information about specific Census variables and concepts can be found in the 2021 Census dictionary, which includes a glossary of terms and definitions to give data users an understanding of the Census and Census topics.

More information about the background and planning of the Census can be found in Background and planning documentation.

Scope and coverage

The 2021 Census of Population and Housing aimed to count every person in Australia on Census Night, 10 August 2021.

The people counted in the 2021 Census include:

  • People in the six states and six territories (Northern Territory, Australian Capital Territory, Jervis Bay Territory, Territory of Christmas Island, Territory of the Cocos (Keeling) Islands and Norfolk Island)
  • People who leave Australia but are not required to undertake migration formalities (e.g. people who work on oil or gas rigs)
  • People on vessels in or between Australian ports
  • People on board long-distance trains, buses or aircrafts within Australia
  • People entering Australia before midnight on Census Night
  • Visitors to Australia (regardless of how long they have been in the country or plan to stay)
  • Detainees under the jurisdiction of the Department of Home Affairs in detention centres in Australia
  • People in police lock-ups and prisons.

The people not counted in the 2021 Census include:

  • People in Australian external territories (minor islands such as Heard and McDonald Island)
  • Foreign diplomats and their families (derived from the Vienna Convention)
  • Foreign crew members on ships who remain on the ship and do not undertake migration formalities
  • People leaving an Australian port for an overseas destination before midnight on Census Night.

The 2021 Census of Population and Housing also counted private dwellings (such as houses, apartments and caravans) and non-private dwellings (such as hotels, hostels and hospitals).

The dwellings counted in the 2021 Census include:

  • All occupied and unoccupied private dwellings
  • Occupied caravans in caravan parks and manufactured homes in manufactured home estates
  • Occupied non-private dwellings, such as hospitals, prisons, hotels, etc.
  • Unoccupied residences in retirement villages (self-contained)
  • Unoccupied residences of owners, managers or caretakers of such establishments.

Unoccupied non-private dwellings are out of scope of the 2021 Census.

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