Quality declaration

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Census methodology
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First release

This quality declaration details how the Census addresses each of the elements of the ABS’s quality framework, covering relevance, timeliness, accuracy, coherence, interpretability, and accessibility.

Institutional environment

For information on the institutional environment of the ABS, including the legislative obligations of the ABS, financing and governance arrangements, and mechanisms for scrutiny of ABS operations, please see ABS Institutional Environment.


The Australian Census of Population and Housing is a count of population and dwellings and collects details on age, sex and other characteristics of the population.

The Census aims to measure the number and key characteristics of dwellings and people in Australia on Census Night. All people in Australia on Census Night are in scope, except foreign diplomats and their families. Visitors to Australia are counted regardless of how long they have been in the country or how long they plan to stay. Australian residents not in the country on Census Night are out of scope of the Census.

Topics collected by the Census change from time to time. There must be a demonstrated national need for Census data for policy development, planning and program monitoring. Details on the changing content of Censuses from 1911 to 2021 can be found in Background and planning documentation. A copy of the 2021 Census Household Form is included in educational resources.

In 2021, two new questions on long-term health conditions and Australian Defence Force service were included in the Census. In addition, a third response category was added to the sex question to allow people to identify as non-binary sex. The ancestry question was also expanded to allow for more detailed responses for people of Aboriginal and Torres Strait Islander ancestry.

Updated classifications were used for the coding of geographical units, occupation, industry, cultural and ethnic groups, language, religion, and countries. For more detail see the 2021 Census dictionary.


The Census and Statistics Act 1905 requires the Australian Statistician to conduct a Census on a regular basis. Since 1961, a Census has been held every 5 years. The 2021 Census was the 18th national Census and was held on 10 August 2021.

The 2021 Census has two main releases: 

  1. The first comprehensive Census dataset released in June 2022 provides community level Census data for a wide range of topics, including information on small population groups and for small geographic areas such as suburbs and local government areas.
  2. Detailed Census data released in October 2022 contains data on employment, qualifications and population mobility including journey to work and internal migration data.

An additional wave of Census-related data released from 2023 onwards adds further value to the main data releases in 2022.


The ABS aims to produce high quality data from the Census. To achieve this, extensive effort is put into Census form design, collection procedures and processing. There are four principal sources of error in Census data which quality management aims to reduce as much as possible. They are respondent error, processing error, non-response and undercount. For more detail, see Managing Census quality.

The Census is self-enumerated and respondents sometimes do not return a Census form or fail to answer every applicable question. Persons are imputed into dwellings for which no form was returned, together with some demographic characteristics for these people (age, sex, marital status, usual address and place of work). These same demographic characteristics are imputed if not provided by respondents on a returned form. However, the majority of output classifications include a 'not stated' category to record the level of non-response for that data item. Data use considerations are produced for each Census variable and include non-response rates where relevant, along with a comparison of non-response rates for the 2016 Census and a brief outline of any known data quality issues. Data use considerations are included in the 2021 Census dictionary.


It is important for Census data to be comparable and compatible with previous Censuses and also with other data produced by the ABS and wider community. Changes to existing questions on the Census are tested and evaluated to manage any impacts on data, and new Census questions are carefully designed to ensure that differences with other data sources are explainable. The ABS and the Census also use Australian standard classifications, where available and appropriate, to provide data comparability across statistical collections. These include for example, standards for occupation and geographic areas. For more details regarding classifications used in the Census, see the 2021 Census dictionary and the relevant entries for each classifications.


An extensive range of online products are available on the ABS website. The ABS works to ensure all products are as accessible and usable as possible, undertaking testing of colours, images, navigation and language. See more about accessibility.

If the Census information you require is not available as a standard product or service, ABS Consultancy Services can help you with customised services to suit your needs.

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