Appendix A Observations from the 2016 Report – what was implemented and how

Historically, the occupancy of a dwelling in censuses was largely determined by field observation, including contact with the householder or neighbours. Occupancy was also determined when householders directly phoned the Census Contact Centre.

While occupancy rates in the 2016 Census were consistent with previous Censuses, the 2016 Post Enumeration Survey indicated that a proportion of dwellings were incorrectly deemed as occupied on Census night and therefore that the 2016 occupancy rates were over-stated. The 2016 Census Independent Assurance Panel highlighted the opportunity to improve the accuracy of occupancy determination.

New approaches implemented in the 2021 Census include:

• In 2021, householders could use the Census Digital Service to advise that a dwelling was unoccupied on Census night. There were two ways of doing this. First, through the online Census form in which householders who entered ‘0’ persons present were streamed out of the form to report the dwelling as unoccupied. This pathway was called the ‘zero stream’. A second method was to use a new self-service option on the Census website that allowed respondents to advise they were away on Census night.
• In addition, the 2021 Census used a probability model to create an indicator of occupancy. The model used administrative data and was applied to dwellings where insufficient information was obtained in the field to definitively determine if the dwelling was unoccupied. This process was applied as part of data processing.

More information about these approaches is published on the ABS website.[1]

[1] See Australian Bureau of Statistics (2020). Assessing administrative data to enhance the 2021 Census. Available at https://www.abs.gov.au/statistics/research/assessing-administrative-data-quality-enhance-2021-census

The 2016 Census dwelling imputation method was a standard nearest neighbour ‘hot-decking’ approach, which imputed people into non-responding dwellings by finding a similar dwelling, called a donor, from the responding population by matching on (limited) known information. While the method improved the overall Census counts, the 2016 Post Enumeration Survey indicated that there was some ‘age skewing’ of the imputed population, with older persons over-represented.

In response to this recommendation, the ABS used administrative data to improve the ‘hot-decking’ approach so that it chooses the donor based on similar administrative data characteristics (see Figure A.1). Based on simulations using 2016 Census data, this approach reduced the over-representation of older persons and thereby improved the overall age distribution of Census counts.

The recommendation to consider ‘post-Census’ adjustments at the small area level based on the Post Enumeration Survey was not pursued. Maintaining the current approach provides continuity of approach and data with previous Censuses.

NR  Non-Responding

R  Responding

With the move to a frame-based mail out model in 2016, field staff no longer visited every dwelling and dwelling structure data was not collected for every dwelling in the field. Instead, the 2016 Census relied on information sourced from the Address Register for mail out areas, supplemented by Census field information, where collected. At that point in time, dwelling structure data on the Address Register was largely populated by a large canvassing exercise undertaken in 2015.

The 2016 Census Independent Assurance Panel concluded that the use of the ABS Address Register likely led to the increase in the number of dwellings that did not have a structure type, as well as a decrease in the proportion of dwellings classified as flats and apartments attached to houses, noting that the proportion of dwellings affected was small.

Since the 2016 Census, dwelling structure information on the Address Register has been significantly improved through the following activities:

• applying dwelling structure information from 2016 Census data to 9.6 million addresses;
• using Building Approvals dwelling structure data for approximately one third of new dwellings and for updating existing semi-detached dwellings and low-rise apartment blocks;
• updating the dwelling structure standard resulting in two main changes: firstly, improved clarity in the definition of separate and semi-detached dwellings and secondly, addition of a ‘9 or more storey’ classification;
• developing an imputation model to assign dwelling structure when no other data is available (approximately 3.5% of residential addresses), ensuring that every residential address record on the 2021 Census frame has an assigned value for dwelling structure.

In addition to these measures on the Address Register, field staff collected dwelling structure for those dwellings visited. Where the dwelling has an imputed value, this was updated with field information.

The introduction of a new self-service option on the Census website that allowed users to complete their Census without the code and password delivered to their address, resulted in an increase in the number of dwellings without a dwelling structure. These dwellings were assigned an imputed dwelling structure where there was sufficient geographic location information for use in the imputation model.

Although the 2016 Census results for Aboriginal and Torres Strait Islander peoples were comparable with the 2011 Census, the 2016 Census Independent Assurance Panel noted that the coverage of these populations remained much lower than that of the general population and that the ABS should consider ways of improving this coverage.

The ABS undertook user-centred research early in the design of the 2021 Census to understand drivers of participation by, and avenues for increasing response from, Aboriginal and Torres Strait Islander peoples. ABS built on this research through ongoing consultation with the ABS Round Table on Aboriginal and Torres Strait Islander Statistics. Through this work the ABS developed and enacted a number of strategies to address this recommendation. The approach has included:

• Greater investment in the dedicated engagement unit enabling early and ongoing engagement at all levels, from grass roots community organisations through to governance bodies. 
• Employing locally and increasing the number of Aboriginal and Torres Strait Islander office and field staff, including having designated positions in Remote Area Teams and Census Engagement Managers working with communities. To achieve this, ABS had a dedicated recruitment team that included Aboriginal and Torres Strait Islander staff.
• Engagement of a specialist Aboriginal and Torres Strait Islander agency to help the ABS deliver culturally appropriate communication. This included tailored campaign materials, radio advertising in 19 languages, and media placement in Aboriginal and Torres Strait Islander press, radio, and television. The Census Program appointed 21 Aboriginal and Torres Strait Islander media spokespeople from within the ABS and worked closely with Aboriginal and Torres Strait Islander media organisations. A suite of information material was developed to support oral, written and visual communication, and shared this with stakeholders through engagement teams.
• Partnerships with community organisations to create culturally safe locations for assistance in form completion. Unfortunately, this measure had to be scaled back or cancelled in New South Wales and Victoria due to the COVID-19 outbreak.
• Improvements to Census forms that include ‘Aboriginal’ and ‘Torres Strait Islander’ as listed ancestries, and changes to increase reporting of Aboriginal and Torres Strait Islander languages.
• Testing online and paper forms with Aboriginal and Torres Strait Islander peoples. Testing occurred in focus groups and through ongoing consultation with the Round Table on Aboriginal and Torres Strait Islander Statistics.

In addition to the above, one of the most significant improvements was the digitisation of field operations for remote areas. This involved remote teams using a mobile app instead of paper record books and accessing near real time operational intelligence. For the first time, staff managing remote operations were able to review all dwelling and person counts in near real time.

The ABS has also researched statistical methods to reduce the undercount of Aboriginal and Torres Strait Islander peoples in the Census. Two options were developed. The first was to extend existing hot-deck dwelling imputation to include Indigenous status in addition to Age, Sex and Marital status. This research was presented to a wide range of external stakeholders, with feedback that there was merit in the approach to reduce undercount, but there were strong reservations about imputing Indigenous status. Based on this feedback Indigenous status was not included in 2021 Census hot-deck dwelling imputation. A second option was later developed as a potential contingency for low response. This involved using administrative data records for people not responding to the Census and showed further improvements to the undercount. While this latter measure was not needed for the 2021 Census, the ABS will continue this research to show potential improvements for future Censuses.

The 2016 Census Independent Assurance Panel noted that although the overall population in non-private dwellings was relatively small, the lower response rates in these dwellings had some effect on quality. Specifically, the Panel recommended improving the measure of actual occupancy in these dwellings on Census night and therefore the number of non-responding persons that should be imputed.

In 2021, field processes and systems were improved to more accurately capture the occupancy of each non-private dwelling on Census night. In addition, persons staying in non-private dwellings were also able to complete their Census through the self-service option on the Census website that allowed users to complete their Census without a code and password.

Despite these measures, the 2021 Census experienced challenges in monitoring the progress and quality of enumeration in non-private dwellings during field operations. The COVID-19 lockdowns and travel restrictions reduced travellers in many areas and resulted in lower levels of occupancy than expected.

Furthermore, COVID-19 impacted a number of specific dwellings, notably hospitals and aged care providers, which were experiencing extreme staffing restrictions and pressures. In these circumstances, a reduced set of information was collected from these dwellings.

The 2016 Census Independent Assurance Panel noted a decline in the reporting of date of birth and the reduced proportion of people choosing to have their form retained by the National Archives. They identified an opportunity for the ABS to consider how best to respond to privacy concerns about the Census and provide appropriate assurances to the public. It was also suggested that the ABS consider sourcing an external Privacy Impact Assessment for future Censuses.

As in previous Censuses, the 2021 Census had a strong emphasis on maintaining the privacy and security of Census data. The ABS has undertaken extensive stakeholder engagement, gained external privacy advice and assurance (including a whole-of-Census Privacy Impact Assessment), and implemented a strong risk management program.

In line with the ABS’s commitment to privacy and maintaining public trust, the 2021 Census Program undertook two independent PIAs, consulting with a range of stakeholders, including privacy regulators, researchers and civil society advocates:

• The ABS commissioned Galexia Pty Ltd to conduct the 2021 Census Privacy Impact Assessment. This assessment focused on potential privacy risks and issues associated with personal information collected by the ABS. All recommendations were accepted except for the recommendation to exclude the Long-term health conditions question from the Census Time Capsule – the repository of forms that respondents have agreed can be kept by the National Archives and be accessed in 100 years.
• A separate Privacy Impact Assessment was conducted on 2021 Census Administrative Data, by Information Integrity Solutions Pty Ltd. This assessment looked at how the potential use of administrative data could affect privacy. That is, using information collected by other government agencies, businesses or other organisations to support the Census. The ABS agreed with all the recommendations from this assessment.

The results of the Privacy Impact Assessments[1], as well as other privacy material has been published on the ABS website throughout the Census development period and during operations. This included the 2021 Census Privacy Statement[2] and collection notices, which provide clear information on how the ABS collects, stores and deletes personal information. The ABS also published articles explaining the use of administrative data in the Census.

[1] Australian Bureau of Statistics (2021) Privacy Impact Assessments: 2021 Census of Population and Housing. Available at https://www.abs.gov.au/about/legislation-and-policy/privacy/privacy-impact-assessments

[2] Australian Bureau of Statistics. 2021 Census Privacy Statement. Available at https://www.abs.gov.au/about/legislation-and-policy/privacy/privacy-abs/2021-census-privacy-statement

This recommendation was readily accepted by the ABS and the 2021 Census Statistical Independent Assurance Panel was established with similar Terms of Reference to the 2016 Panel and has concluded with the publication of this report.