How the data is collected

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How the data was collected

Census data is collected using a variety of methods and employs specific strategies to ensure the count on Census Night is as accurate as possible.

To collect Census data, the ABS contacts households in different ways. Letters and paper forms are delivered in some areas, and in other areas visits are made to households. Households complete the Census form and submit it online or send it back through the mail.

Counting each person and dwelling on Census Night takes a lot of planning and many people. The ABS engages a large, geographically dispersed temporary field workforce of about 32,000 ABS officers who have strict obligations under legislation to make contact with households and provide Census materials.

In the months leading up to a Census, field staff make sure businesses and services are prepared with enough forms for every person in every dwelling to participate. We enlist the help of hotels, motels, hospitals, aged care facilities, student accommodation and many other establishments to ensure guests, patients and residents are ready for the Census.

The bulk of field staff are employed to deliver Census materials to homes, or to visit homes after Census Night where we have not received a completed form. Specialist field staff are also recruited to support people who are hard to reach or who may need help completing their Census form.

2021 Census enumeration model

In 2016, the ABS developed a new digital approach to the Census enumeration model. This approach provided a faster, more efficient, environmentally friendly Census than any previous Australian Census. The 2021 Census enumeration model was based on the successful elements of the 2016 Census with additional improvements to the way Census materials were delivered and collected.

To maximise the public’s ability to participate in the Census, the ABS divided Australia into three delivery areas, in most part based on the quality of the ABS Address Register and availability of mail services in that area. Each area had its own strategy for public engagement and collection of forms.

2021 Census enumeration model

Map of Australia displaying Remote Area Strategy, Drop-off strategy and Mail-out strategy.

2021 Census enumeration model

This map of Australia shows how the Census was delivered across Australia. It displays areas in different colours indicating where a Remote Area Strategy (RAS), Drop-off strategy and Mail-out strategy was required.
1. Mail-out areas
  • Mail-out areas included known addresses, identified using the ABS Address Register. Most dwellings in these areas were delivered a Census instruction letter and some were delivered a paper form. Each letter had a unique login code which respondents could use to access an online form as well as information on how to request a paper form. In 2021, approximately 85% of dwellings were in mail-out areas.
2. Drop-off areas
  • Drop-off areas were mostly rural areas, including small towns without street delivery service. Census field staff delivered paper forms to dwellings in these areas which in 2021, comprised approximately 15% of all dwellings. Paper forms also included unique login codes enabling these households to complete the form online.
3. Remote areas
  • Representing 0.5% of all private dwelling, 46% of Australia’s total land mass was treated as remote areas. This included most of the Northern Territory and large parts of Western Australia, Queensland and South Australia as well as overseas territories. Respondents participating in many remote areas were offered the opportunity to complete the Census through an interview or to self-respond using the online form or a paper form collected by a field officer.

If a dwelling had not received either a letter or paper form with a unique login code, households were able to request a login code via the Census Digital Service and complete the form online or request a paper form. Approximately 1.45 million Census forms were submitted through self-service.

Within each of the three area-based strategies, there were adaptations which enabled small areas to be treated such that Census response rates could be maximised according to the characteristics of each area. These included providing a paper form instead of a Census instruction letter and starting follow-up visits early to remind residents to complete their Census.

The 2021 Census was the first time that the ABS actively encouraged households to complete and submit their Census form as soon as they received their materials, meaning this could be done before Census Night on 10 August. The letters also emphasised 12 August as a date after which the household may receive contact from the ABS. This messaging was designed to provide a ‘response window’, where previous censuses highlighted Census Night only.

A range of operational information, including completed online and paper Census forms, call centre agents, the Census Digital Service and field staff observations, provided the ability to monitor progress in real-time at small area levels, and was used to highlight issues such as areas of low response, so that strategies could be enacted quickly to respond.

If a dwelling had not returned a Census form by Census Night, reminder and non-response procedures were carried out by Census field staff, which included house visits and reminder letters, to ensure everyone in Australia on Census Night was counted.

Special collection strategies

The ABS uses a range of approaches for specific population groups to ensure the coverage of people in Australia is as complete as possible. These strategies are designed, in consultation and collaboration with relevant communities and service providers, to ensure these groups participate in the Census and accurate information is collected.

Special strategies were developed to optimise accessibility and inclusion of the following groups:

  • people living in remote areas
  • Aboriginal and Torres Strait Islander people
  • defence personnel
  • people with disabilities
  • people experiencing homelessness
  • people from culturally and linguistically diverse backgrounds
  • people in communal types of accommodation or care, such as hotels, hospitals or hostels for the homeless
  • people in dwellings co-located or grouped together, such as retirement villages and marinas
  • people travelling or away from their home on Census Night
  • people living in mining camps and fly-in/fly-out workers
  • older Australians.
Each of these strategies had one or more of the following components:

Specialised field staff

Specialised field staff were employed to undertake specialist collection tasks. For example, locating hard-to-find populations, managing the distribution and collection of forms in complex housing establishments, or conducting interviews with respondents. A key objective when employing these field staff was to select people who were trusted by and knowledgeable of the people to be counted under this strategy.

Alternative Census forms

Alternative Census forms were used as part of some strategies. An Interviewer Household Form was used in remote Aboriginal and Torres Strait Islander communities and in some urban areas. In some areas, a shortened version of the Census form was used to interview people sleeping rough as part of the Homelessness Enumeration Strategy. Forms were also available with large print, in braille and translated into Auslan. In 2021:

  • 7006 large print forms were returned
  • 20 braille forms were returned
  • Auslan videos were played 9166 times
  • audio content was played 9257 times.

The ABS has worked to provide the online Census form as accessible to Level 2.0 AA and tested the form with screen-readers and other assistive technologies. The ABS website was awarded ‘Government website of the year’ in the 2021 Australian Access Awards.

Targeted communication

The ABS recognises that some people have difficulty or face barriers to completing the Census. For example, they might be away from home on Census Night, live in a remote area or have difficulties understanding English. To overcome these barriers, a range of targeted communication strategies were developed to enable everyone to participate in the 2021 Census. For example, Census promotional and instructional materials were translated into a number of different languages, a phone based translation service was available and multilingual staff where engaged with specific communities.

Community engagement

The ABS engaged with both national and local community organisations and stakeholders in order to understand the support needs of different communities, provide information on the importance of participation in the Census and to assist with completing Census forms. A number of community initiatives were employed including the introduction of more than 300 pop-up hubs across Australia in both urban and regional locations. These hubs provided a friendly and supportive environment for members of the public to have their questions answered and be encouraged to participate in the Census. The ABS also offered more than 100 general ‘fill in the form’ sessions at community centres where one-on-one support was offered to people to complete the Census.

Conducting a Census during a pandemic

The 2021 Census was undertaken during a unique time in our history, when many areas across Australia were operating under lockdown restrictions due to COVID-19. Movement in and out of Australia was restricted, limiting overseas travel for Australians and the number of overseas visitors within Australia.The pandemic and the subsequent restrictions had many impacts on people’s daily lives, including on employment, travel and education. 

The ABS was prepared to conduct the Census during the pandemic, implementing robust contingency plans and testing them in a major test in October 2020. This included a COVID-safe plan, which detailed how we would deliver the Census, manage our staff in the field and keep the community safe in line with government health orders.

Census field officers were deemed authorised workers so they could deliver Census materials to households. In areas under restrictions, contactless procedures for field activities were enacted under the ABS Census COVID-safe plan, and face-to-face support activities like pop-up hubs and 'fill in the form' sessions were offered virtually where possible or cancelled. These changes may have impacted how people accessed Census support, before, after and on Census Night. Additionally, restrictions may have affected where people were on Census Night and their responses to the questions.

Restrictions on geographic areas

Many areas experienced restrictions leading up to, on and after Census Night.

For example, parts of South Eastern Australia moved in and out of lockdown over the Census ‘response window’ in early August 2021:

  • Leading up to Census Night, Victoria entered a state-wide lockdown. This remained in place for Greater Melbourne and Shepparton until after Census Night, while most of regional Victoria had restrictions lifted on 10 August.
  • Greater Sydney and many parts of regional New South Wales experienced lockdown restrictions during the Census response period.
  • South East Queensland was in lockdown shortly before Census Night, but this was lifted on 8 August. Cairns and Yarrabah however, were placed in lockdown on 8 August for a short period.
  • The ACT was placed in lockdown shortly after Census Night on 12 August.

What was happening at the time was different for each state and territory and for different areas within those states and territories. For example, Western Australia did not experience the same restrictions as New South Wales or metropolitan Melbourne, so the data may look quite different when comparing trends at a state/territory level. To see an approximate guide to the restrictions in place during the Census enumeration period, see Downloads.

People living with COVID-19 lockdown restrictions were still required to complete the Census. ABS provided advice to the public on how to respond to questions related to study and work impacted by the change of circumstances.

Census Digital Service

The Census Digital Service was developed by the ABS (in partnership with PwC and Amazon Web Services) to provide a highly secure platform that included the website, online Census form, self-service and assistance.

The 2021 Census Digital Service offered a range of innovative online self-service options. People could:

  • request a paper form (approximately 67,000 requests made)
  • report they would not be at home on Census Night (over 94,000 notifications received)
  • control their password, including a password reset
  • login without a Census letter or request a Census number (approximately 1.75 million requests).

Census forms

There were a number of ways information was collected from the Australian public. For most people, information was returned to the ABS via either an online form or a paper form.

The 2021 Census collected responses on two new topics – Long-term health conditions and Australian Defence Force service. These were the first significant changes to the information collected in the Census since 2006. Changes were also made to the way certain topics were collected. Notably, response categories of 'Aboriginal' and 'Torres Strait Islander' were added to the Ancestry question, respondents had the option of identifying as non-binary sex, and the Language question was updated to refer to language used (rather than language spoken) to enable inclusion of sign languages such as Auslan. The changes were designed based on the 2021 public consultation process, evaluation of the results of the 2016 Census, and the 2021 Census testing program.

Online form

The 2021 Census online form was improved greatly from previous Censuses. Developments were made to make the form simpler for people to use and easier to complete. The improvements included:

  • improved sequencing of respondents to only the questions relevant to them based on information they have provided
  • increased use of automatically populating questions with previously entered information, such as address or language spoken at home, to make the question easier to respond to
  • additional in-built edits to check for valid responses
  • greater use of supplementary questions to improve accuracy of response for industry and occupation questions

The improved online form significantly reduced the time taken by the average household to complete the Census and delivered high quality data. Two thirds of Australians rated their online experience as good and many noted how easy it was to complete.

Paper forms

The paper household form and personal form enabled people to fill out forms manually and post them back in the mail. The paper forms also included a unique login ID and instructions for completing online.

Other versions of paper forms were used for areas or populations where a different approach was required. For people experiencing homelessness, field officers used Special Short Forms to collect their information. For people living in remote Aboriginal and Torres Strait Islander communities, households had the option to provide information directly to a field officer using an Interviewer Household Form, or could complete their own paper or online form. Sample copies of the 2021 Census paper forms can be viewed under resources. 

Mode of response

How people in each state and territory completed their Census

In 2021, 83.5% of people in occupied private dwellings submitted the Census form online compared to 63.4% in 2016.

For private dwellings, 78.9% submitted their Census form online in 2021 suggesting that households with more people in them were more likely to use an online form.

Advancements in technology and the introduction of the Census Digital Service in 2021 made it easier for people and households to complete their Census form online and contributed to the increased shift towards an online mode of response.

Mode of response for responding occupied private dwellings by state and territory, 2011, 2016 and 2021
 2011 Paper form (%)2011 Online form (%)2016 Paper form (%)2016 Online form (%)2021 Paper form (%)2021 Online form (%)
New South Wales64.535.540.
South Australia69.330.748.
Western Australia62.937.138.561.517.682.4
Northern Territory66.233.850.649.425.174.9
Australian Capital Territory53.746.321.178.96.893.2

(a)  Includes Other Territories (Jervis Bay Territory, Territory of Christmas Island, Territory of the Cocos (Keeling) Islands and Norfolk Island). 

In 2021, the majority of people in non-private dwellings submitted their Census information using a paper form. While this was also the case for the 2011 and 2016 Census, there has been an increase across all states and territories in the uptake of the online form option by people staying in non-private dwellings on Census Night.

One in three people in non-private dwellings on Census Night (33.3%) submitted their Census form online compared 9.5% in 2016.

Mode of response for people enumerated in non-private dwellings by state and territory, 2011, 2016 and 2021
 2011 Paper form (%)2011 Online form (%)2016 Paper form (%)2016 Online form (%)2021 Paper form (%)2021 Online form (%)
New South Wales92.17.989.710.362.437.6
South Australia88.511.590.99.174.525.5
Western Australia94.45.691.78.465.934.1
Northern Territory96.63.491.68.452.147.9
Australian Capital Territory74.725.380.519.559.140.9

(a)  Includes Other Territories (Jervis Bay Territory, Territory of Christmas Island, Territory of the Cocos (Keeling) Islands and Norfolk Island). 

How culturally and linguistically diverse communities completed their Census

People born outside Australia were more likely to participate online (89.1%) than people born in Australia (82.2%). Of the top 10 countries of birth in Australia, the highest online response was from people born in China (97.1%) and India (97.0%).

(a) Persons in occupied private dwellings only.

(b) Top 10 countries based on the 2021 Census.

People who only spoke English at home were least likely to participate online (80.9%), whereas people who could not speak English at all were the most likely to complete the online form (94.9%).

(a) Persons in occupied private dwellings only.

How different ages completed the Census

Overall, the online response rate for all age groups increased when compared to 2016. Like 2016, the online response rate reduces in older age groups however, online participation for people aged 80 years and over increased by the greatest proportion in 2021 with the online response rate increasing from 28.4% in 2016 to 48.7% in 2021.

(a) Persons in occupied private dwellings only.


COVID-19 restrictions by Local Government Areas

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