Posted 25/02/2015 by Aaron Greenup
The Australian Statistician, David Kalisch, announced on 19 February that, as part of the options for transforming its statistical collections, the ABS is considering changes to the way it runs, and potentially, the frequency of the Census (Reforming the Australian Bureau of Statistics, ABS Media Release, 19 February 2015).
This article is part of a series of FlagPosts exploring what the Census is, why it’s important, how other countries run censuses, and what the alternatives—either officially proposed or informally discussed—may be.
Census and counting the population
The Census is without doubt the biggest single activity the ABS undertakes; currently run nation-wide once every five years (next scheduled for August 2016). In its current form it fulfils two roles, the first being the more traditional role of a census, a population count, and the second being a means to which social and demographic data can be collected for the whole population at the same time.
While the aim of the Census is to accurately measure the number and key characteristics of people who are in Australia on Census Night, and of the dwellings in which they live, it is not the official measure of population. The official measure is the Estimated Resident Population (ERP, Australian Demographic Statistics, cat. no. 3101.0). It is ERP that is used to determine the distribution of government funding and define electoral boundaries (amongst others), not the Census.
The ABS recalibrates this ERP every five years using Census data, as well as Census coverage data (produced from the Census Post Enumeration Survey, Census of Population and Housing - Details of Undercount, cat. no. 2940.0) and other data to ensure population estimates continue to be as accurate as possible.
Between censuses, the ERP at the National and State/Territory levels is updated quarterly using administrative data relating to births, deaths and migration (overseas and interstate). For smaller geographic areas, the ERP is updated annually using models based on indicators of population change, such as dwelling approvals, Medicare enrolments and counts of people on the Australian Electoral Roll, as statistics on migration at fine geographic levels are not reliable (Regional Population Growth, Australia, cat. no. 3218.0).
Why is the Census important?
One of the most important uses of Census data is to provide a means of recalibrating, or rebasing the ERP. Without this recalibration or rebasing process the ERP could vary from what the actual population is. The Census provides the ABS with the opportunity to assess the extent of any variation of ERP and to review their modelling and make modifications if necessary.
In addition to providing a means of ensuring quality population estimates are maintained over time, the Census also provides a rich snapshot of demographic and social data at very fine geographic levels. This information is valuable for researchers, businesses and for governments at every level.
What are the implications of change?
The ABS is yet to announce what changes are being proposed for the Census, however, the key considerations for any change will be:
- How will the changes to Census affect ERP calculation?
- How will the changes impact on the availability of very fine geographic levels of detailed demographic and social data?
The next FlagPost in this series will explore how other countries conduct a census, and what methods they use.