The ABS has identified three uses for administrative data to enhance the 2021 Census. They are to:
- maximise Census response by identifying areas where people may need extra support to complete the Census;
- improve the Census count by refining our methods to estimate the number of households unoccupied on Census night; and
- prepare for any unexpected events that could impact the Census response (e.g. natural disasters).
These three uses of administrative data to enhance the 2021 Census have been assessed and supported from a Privacy perspective (refer ABS Privacy Impact Assessments). In this article we assess administrative data from a quality perspective.
For administrative data to be of most use in the 2021 Census, we need to know how accurately it represents Australia’s population. One important way of making this assessment is by comparing population counts created from the administrative data with the ABS’s official population counts at the time of the 2016 Census.
Overall, our research shows administrative data represents the Australian population very well. Looking back at the Census in 2016, the difference between a measure of Australia’s population from administrative data and the official ABS population estimate for Australia is only about 8,000 people, or 0.03% of the population. The national age profile is very similar, and differences for the states and territories are also very small.
However, bigger differences start to become apparent as we ‘zoom in’ on smaller geographic regions and population groups across the country. For example, younger Australians in their twenties appear to be under-represented by the administrative data, particularly some specific groups like international students in Melbourne.
The remainder of this article is organised as follows. Section 2 describes our approach to combine administrative datasets to represent Australia’s population. Section 3 provides the results and answers the question ‘How accurately do counts from the combined administrative data compare with official ABS counts?’ at the national level, for states and territories, and for smaller geographic regions. Section 4 outlines further research.