2940.0 - Census of Population and Housing: Details of Overcount and Undercount, Australia, 2016 Quality Declaration 
ARCHIVED ISSUE Released at 11:30 AM (CANBERRA TIME) 27/06/2017   
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Tuesday 9 August 2016 was Census night in Australia. All people present in Australia on this night, with the exception of foreign diplomats and their families, should have been included on a Census form at the place where they stayed.

The Census of Population and Housing (Census) is the largest statistical collection undertaken by the Australian Bureau of Statistics (ABS) and one of the most important. Its objective is to accurately measure the number of people in Australia on Census night, their characteristics, and the dwellings in which they live. Due to its size and the complexity of this task, however, it is inevitable that some people will be missed from the Census and some will be counted more than once.

The Census Post Enumeration Survey (PES) is run shortly after each Census as a way to independently measure Census coverage. The PES determines how many people should have been counted in the Census, how many were missed, how many were counted more than once, and how many were counted in error.

The PES also provides an estimate of Census imputation error; i.e. the difference between the number of people imputed into non-responding dwellings during Census processing and the number of people who should have been counted in those dwellings. It also provides information on the characteristics of those in the population who have been missed or overcounted, including an indication of those characteristics which may have changed or been misclassified between the Census and PES.

Some of the reasons why people may have been missed in the Census (i.e. undercounted) include:

  • they were travelling and were difficult to contact
  • they mistakenly thought they were counted elsewhere
  • there was insufficient space on the Census form in the household where they were staying and they did not obtain additional forms
  • the person completing the form thought that certain people (e.g. young babies, the elderly or visitors) should not be included
  • they did not wish to be included due to concerns about confidentiality or a more general reluctance to participate
  • the dwelling in which they were located was missed because it was difficult to find (e.g. in a remote or non-residential area) or the dwelling was not included on the ABS Address Register
  • a Census form (including online registration) was not supplied as the dwelling was mistakenly recorded as unoccupied, and no forms for that dwelling were requested.

Some of the reasons why people may have been counted more than once or in error (i.e. overcounted) include:
  • they were included on the Census form at the dwelling where they usually live, even though they stayed and were counted elsewhere on Census night
  • they moved during the Census period and completed forms at both their previous and new address
  • they were overseas on Census night and so should not have been counted at all, but were included on the Census form at the dwelling where they usually live.