Glossary

According to the Commonwealth definition[1], an Aboriginal or Torres Strait Islander is a person of a. Aboriginal and Torres Strait Islander descent, b. who identifies as an Aboriginal or Torres Strait Islander and c. is accepted as such by the community in which he or she lives.

The Census and Post Enumeration Survey collect information on a person’s reported (self-identified) Indigenous Status. See Indigenous Status.

[1] Department of Aboriginal Affairs (1981). Report on a review of the administration of the working definition of Aboriginal and Torres Strait Islander, Canberra: Commonwealth of Australia. Department of the Parliamentary Library, 2003. Defining Aboriginality in Australia, Canberra. Commonwealth of Australia.

A framework developed by the Census Statistical Independent Assurance Panel for use in assessing the sources and types of error that might affect the accuracy of the Census and population estimates. This framework is covered in detail in Appendix B.

A comprehensive list of Australian addresses developed using the Geocoded National Address File. Other administrative datasets are also used to update the Register, such as Australian Electoral Commission data and ABS Building Approvals and Demolitions data. The Address Register does not contain any information about the occupants of the address. The Address Register was built by the ABS in the lead up to the 2016 Census and is regularly updated by its management team. The Address Register is a national resource that is owned and hosted by the ABS.

In the context of the Census, an anchor point is an event that assists in the recollection of a person, dwelling or family’s circumstances on Census night.

The ABS identifies six states and six territories in Australia. The six states are New South Wales, Victoria, Queensland, South Australia, Western Australia, and Tasmania. The six territories are Northern Territory, Australian Capital Territory, Jervis Bay Territory, Territories of Christmas Island, Cocos (Keeling) Islands, and Norfolk Island.

Automated processes used to determine possible links between Census and Post Enumeration Survey data, before any clerical matching processes (such as the match and search system) has begun. It links records by using a range of personal and addresses characteristics to evaluate the likelihood that a Post Enumeration Survey and Census record pertain to the same individual.

The Australian Census of Population and Housing is an official count of population and dwellings, and collects details of age, sex, and other characteristics of that population. The Census is conducted every five years, and asks respondents to complete their Census form about their circumstances on Census night.

See accuracy framework

The questionnaire used by people to provide person and dwelling information as part of the Census. The Census form is available online or on paper.

The collection of Census-relevant address information based on the Address Register and other information obtained from Census field staff, the Census Contact Service and other ABS staff. This includes information such as dwelling type and structure and street address.

The Census Contact Centre is a service established to support the public with questions they have about the 2021 Census. This was also used by the public to request Census material. Service offerings included both call and email channels and was supported by an Escalations team who responded to the more difficult customer contacts. The Contact Centre opened on the 5 July 2021 and closed on the 1 October 2021.

For the 2021 Census, Census night was the night of 10 August 2021. People are asked to complete their Census form about their personal circumstances on Census night, but do not have to complete their Census form on Census night.

In the context of the Post Enumeration Survey, the Census contact sector comprises all dwellings that were determined to be occupied on Census night and from which a form was received before the Post Enumeration Survey commenced data collection.

For simplicity, this report refers to “Persons on Census forms” in place of the technical term “Contact Sector”.

See non-contact sector

A bias that can result for Post Enumeration Survey estimates if Statistical Independence is not preserved, that is to say if persons are systematically missing from both the Census and Post Enumeration Survey, beyond what demographic or geographic variables can explain.

See statistical independence

Coverage describes the extent to which people or dwellings that are in scope of the Census are counted in the Census.

A Census data item (or variable) is a characteristic of a person, dwelling or family that is collected in the Census.

The process where some variables are assigned values based on responses to other questions, or (where no response has been provided) from other family members present in the same dwelling. For example, if a person provides their date of birth on their Census form and does not provide an age, then their age is derived (calculated) based on their provided date of birth.

A Discrete Community is a geographic location, bounded by physical or legal boundaries, which is inhabited or intended to be inhabited predominantly by Aboriginal or Torres Strait Islander peoples, with housing or infrastructure that is managed on a community basis.

See field area

A dwelling is a structure which is intended to have people live in it, and which is habitable on Census night. The two main types of dwelling are private and non-private dwellings.

A private dwelling is one that accommodates a person or a group of people and is not generally available for public use. The main purpose of a dwelling is as a place of habitation, and it is usually built (or converted) to function as a self-contained housing unit. Private dwellings include houses, flats and apartments as well as structures that are non-standard or temporary in nature. Examples of non-standard private dwellings are any caravans, sheds, houseboats and tents that are occupied on Census night.

A non-private dwelling is one that provides short or long-term communal or transitory type accommodation. Non-private dwellings are generally available to people for reasons of employment, study, special need, legal requirement or recreation. For example, hotels, hospitals, and prisons are all classified as non-private dwellings.

Occurs when a completed Census form has not been returned for a private dwelling determined to be occupied on Census night.

The percentage of private dwellings identified as occupied on Census night that did not return a Census form.

Occurs when a Census form is returned for a private dwelling identified as occupied on Census night.

The percentage of private dwellings identified as occupied on Census night that returned a Census form.

The process by which Census information is collected about people and dwellings in Australia on Census night. The enumeration process takes many months to complete, and includes the delivery of Census forms or online login codes, the completion of the Census by members of the public, and the return of Census responses to the ABS, as well as other associated activities.

The official measure of the population of Australia based on the concept of usual residence. It refers to all people, regardless of nationality, citizenship or legal status, who usually live in Australia, with the exception of foreign diplomatic personnel and their families. It includes usual residents who are overseas for less than 12 months over a 16 month period. It excludes overseas visitors who are in Australia for less than 12 months over a 16 month period.

A geographical area that is designed to help the ABS conduct the Census. There are two types of field areas: drop off field areas and mail out field areas.

Dwellings within a drop off field area are visited by field staff to deliver paper Census forms to each dwelling.

Dwellings within a mail out field area are first contacted by the ABS via mail, and are posted log in details to complete the online Census form, or a paper Census form.

An ABS employee who is responsible for conducting Census enumeration within a designated field area.

Fitness-for-purpose refers to data that are able to be used for its stated and intended purpose.

Number of persons counted more than once on Census forms, or otherwise counted on Census forms when they should not have been, as measured by the Post Enumeration Survey.

Number of persons missed from Census forms or in dwellings missed by the Census, as measured by the Post Enumeration Survey.

The primary imputation method used for the 2021 Census. The method involves locating a donor record and copying the relevant responses to the record requiring imputation. The donor record must have similar characteristics to the record requiring imputation, and must also have responses to some specific data item(s). In addition, the donor record must be located geographically as close as possible to the location of the record to be imputed. In 2021, administrative data was used in the hot-decking imputation to improve the selection of donors.

A statistical process for predicting values where no response was provided to a question and a response could not be derived (see derivation). The Census imputes persons into non-responding private dwellings that are determined to be occupied on Census night, as well as into any non-private dwellings where a person was known to be staying but no form was returned. This is known as person imputation. The Census also imputes missing responses for some data items (Age, Sex, Marital status, and Place of usual residence) for responding persons who left these fields blank.

The Census and the Post Enumeration Survey use the ABS Standard Indigenous Question[1] to collect information for the ‘Indigenous Status’ variable. The ABS Standard Indigenous Question is based upon the Commonwealth working definition (see Aboriginal and Torres Strait Islander person) but does not include the third element of the Commonwealth definition, namely that ‘an Aboriginal or Torres Strait Islander is a person who is accepted as such by the community in which he or she lives’. Collecting information on the basis of community acceptance is often impractical in a survey or administrative data collection setting and can lead to inaccuracies. For these reasons, it is not included in the ABS Standard. The definition of Indigenous Status is therefore operationalised as whether or not a person identifies as being of Aboriginal or Torres Strait Islander origin.

The term ‘origin’, when used in the context of the operational definition, is considered to relate to a person’s Australian Aboriginal and/or Torres Strait Islander descent and for some, but not all, their cultural identity.

The standard term for this variable is ‘Indigenous Status.’ ‘Indigenous status’ is an acceptable term for use in data collection only, and only in terms of identifying a characteristic of a person. A person’s Indigenous status is determined by their response to the ABS Standard Indigenous Question: “Are you of Aboriginal or Torres Strait Islander origin?” for which categories are: No; Yes, Aboriginal; or Yes, Torres Strait Islander. This question also allows respondents to report that they are both ‘Aboriginal’ and ‘Torres Strait Islander’ if that is how they identify.

[1] Australian Bureau of Statistics (2014). 1200.0.55.008 Indigenous Status Standard, 2014, Version 1.5. Retrieved from http://www.abs.gov.au/ausstats/abs@.nsf/mf/1200.0.55.008

The Interviewer household form is used in Aboriginal and Torres Strait Islander communities. The Interviewer household form is a Census form which is used to record the details of up to 12 people in a household, and some dwelling data. If there are more than 12 people in a dwelling, additional Interviewer household forms are used.

Item non-response occurs in two situations:

• where a household or person returns a form but does not answer one or more questions - these are “item non-response”; and
• where key variables for a non-responding person have been imputed, the remainder of questions are either set to “item non-response” or “not applicable”, dependant on the imputed age of the person.

The item non-response rate is calculated by dividing the number of households or persons who provided a response to a particular question by the number of persons for whom the question would have been applicable, and is expressed as a percentage.

See field area

The main clerical tool used in the processing of the Post Enumeration Survey data, which allows processors to search, view, compare, and record matches between Post Enumeration Survey and Census records.

People enumerated on an overnight journey by plane, train or bus cannot be allocated a dwelling type. This category exists for data processing and data querying processes only.

The Multi-Agency Data Integration Project is a secure data asset combining information on health, education, government payments, income and taxation, employment, and population demographics (including the Census) over time.

See net undercount

Net undercount is the difference between an estimate of the number of people who should have been counted in the Census and the actual Census count (including imputations). This estimate is based on the Post Enumeration Survey conducted after each Census. For a category of person (e.g. based on age, sex and state of usual residence), net undercount is the result of Census undercount, overcount, differences in classification between the Post Enumeration Survey and Census, and imputation error.

A positive net undercount indicates that there are more people that should have been counted in the Census than there were counted in the Census.

A negative net undercount is often referred to as a net overcount. A net overcount indicates that there are more people counted in the Census than there should have been. This can be the result of too many people being imputed in the Census.

An option introduced for the 2021 Census to allow persons who had not received a Census number via the mail or from a field officer to access and complete an online Census form.

In the context of the Post Enumeration Survey, the Census non-contact sector comprises dwellings that were determined to be occupied on Census night, from which no Census form was received (imputed dwellings) or a Census form was received after the Post Enumeration Survey commenced data collection (late returns), and person responses that had insufficient identifier information.

For simplicity, this report refers to “Persons imputed” in place of the technical term “non-contact sector”.

See contact sector

See dwelling

In the context of the Census, there are three types of non-response: dwelling non-response, person non-response, and item non-response. If it is not specified, typically “non-response” refers to dwelling non-response.

In the context of the Census, there are three types of non-response rates: dwelling non-response rate, person non-response rate, and item non-response rate. If it is not specified, typically “non-response rate” refers to the dwelling non-response rate.

A private dwelling at which it was determined that a person or people were present on Census night.

This dwelling type category includes dwellings which exist in off-shore oil rigs and drilling platforms.

A category of the Australian Statistical Geography Standard at the state and/or territory level that has been created for statistical purposes. In 2016, Other Territories includes the territories of Jervis Bay Territory, Territories of Christmas Island, Cocos (Keeling) Islands, and Norfolk Island. The inclusion of Norfolk Island in Other Territories was new for 2016.

Any effect where the Census count exceeds the true population.

See gross overcount

For the Census, an overseas visitor is a person who usually lives in another country and will be visiting Australia for less than a year.

See imputation

Occurs when a person is included on a returned Census form or their information is provided to the Census via administrative data.

The percentage of all people identified in the Census (including those who are imputed) that are included on a returned Census form or that have their information provided to the Census via administrative data.

The address at which a person spent Census night.

The address at which a person has lived, or intends to live, for a total of six months or more in a given year.

See Post Enumeration Survey

The Post Enumeration Survey is a household survey conducted following the Census. This is also known as the Post Census Review. The Post Enumeration Survey allows the ABS to estimate the number of people missed in the Census and the number counted more than once or in error. The Post Enumeration Survey is conducted independently to the Census, and results obtained are used to adjust Census counts in the calculation of Estimated Resident Population figures for Australia.

An estimate (based on the Post Enumeration Survey and Census data) of the number of people who should have been counted in the Census.

See Estimated Resident Population

See accuracy framework

A statistical process used in the Post Census Review to estimate net undercount.

See dwelling

After every Census, the Estimated Resident Population is recalibrated, or ‘rebased’. Rebasing is the process of adding the net overcount or net undercount from the Post Enumeration Survey to the new Census population counts separately at the state/territory, age and sex group level. Further demographic and time adjustments are then made before the Estimated Resident Population data is finalised.

After each Census, the ABS uses Census counts by place of usual residence which are adjusted for undercount to construct a new base population figure for 30 June of the Census year. Because this new population estimate uses the Census as its main data source, it is said to be ‘based’ on that Census and is referred to as a population base.

Rebasing refers to the process by which the ABS uses this new base to update all previously published quarterly population estimates from the previous Census to the most recent Census (the intercensal period).

In the context of the Census, there are three types of response: dwelling response, person response, and item response. If it is not specified, typically “response” refers to dwelling response.

In the context of the Census, there are three types of response rates: dwelling response rate, person response rate, and item response rate. If it is not specified, typically “response rate” refers to the dwelling response rate.

Period of time around Census night (before, on and after) in which people can respond to the Census, using Census night as the reference point for their responses. For the 2021 Census, the ABS emphasised via public messaging that respondents had a ‘window’ of time to complete and return their Census forms.

The Census includes all people who spent Census night in Australia in one of the six Australian states, the Northern Territory, the Australian Capital Territory, Jervis Bay Territory or the Territories of Christmas Island, Cocos (Keeling) Islands and Norfolk Island. All people in Australia on Census night are counted, along with the dwelling they are staying or living in. This also includes people sleeping out or in temporary dwellings. The only groups of people who spend Census night in Australia but are excluded from the Census are foreign diplomats and their families. While most unoccupied dwellings are included in the Census, some exceptions include caravans, tents or non-private dwellings where there were no people staying on Census night.

This dwelling type category includes people on ‘vessels’ travelling between ports in Australian waters i.e. ships, cargo vessels, passenger liners, ocean-going passenger or car ferries and dredges. It excludes foreign-owned cargo vessels and those bound for overseas.

A range of approaches used by the ABS for specific population groups to improve the coverage of people in Australia, and ensure these groups participate in the Census and accurate information is collected. Special strategies exist for a range of population groups, such as Aboriginal and Torres Strait Islander peoples, people with disabilities, people experiencing homelessness, people from culturally and linguistically diverse backgrounds, people travelling or away from their home on Census night, and people staying in non-private dwellings on Census night.

Statistical independence is a mathematical assumption that underlies the Post Enumeration Survey estimation. In the context of the Post Enumeration Survey, statistical independence requires both population independence (that people who were not counted in the Census are no more likely to be missed by the Post Enumeration Survey than people who were counted) and operational independence (that Census operations do not influence Post Enumeration Survey operations and vice versa).

The total net undercount is the same as net undercount. The use of the word “Total” is to distinguish from components such as net undercount for persons on Census forms and net overcount for persons imputed.

Any effect whereby the Census count falls short of the true population.

See gross undercount

A private dwelling at which it was determined no people were present on Census night.

Unrebased Estimated Resident Population counts have not been “rebased” using Census counts by place of usual residence and adjusted for undercount to construct a new base population figure for 30 June of the Census year.

The unrebased Estimated Resident Population for 2021 used in this report was obtained by updating the 2016 rebased Estimated Resident Population using births, deaths, internal migration and international migration between 2016 and 2021. The rebased estimates from the 2021 Census were not available at the time the report was being prepared.

The unrebased Estimated Resident Population for 2016 used in this report (for comparison purposes with unrebased 2021 estimates) was the 2016 Estimated Resident Population as published on 16 December 2021 (prior to rebasing based on results from the 2016 Census).

See place of usual residence

In the Census a person is counted as a usual resident if they usually live in Australia or if they are visiting Australia for one year or more.

See data item