3118.0 - Demography Working Paper 1999/4 - Measuring Census Undercount in Australia and New Zealand, 1999  
ARCHIVED ISSUE Released at 11:30 AM (CANBERRA TIME) 25/10/1999   
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This publication is part of the Demography Working Paper series.

A population census is a valuable data source for analysing the major demographic, social and economic characteristics of, and changes in, the population. It provides statistics for decision-making by governments, businesses, community organisations and individuals. A census also provides a base for post-censal population estimates and projections, which assist in planning and policy-making at the national and local levels.

Whenever a census is undertaken, questions about the completeness and accuracy of the census count invariably arise. In a large and complex exercise such as a census, it is inevitable that some people will be missed and some included more than once. Usually more people are missed than overcounted, so the census count of the population would be less than the true population. This difference is called net undercount. Net undercount can bias census counts because the characteristics of people missed may be different from those of people counted. Rates of undercount can vary significantly for different population groups depending on factors such as sex, age, ethnicity and geographic location.

Most national statistical agencies provide independent measures of census coverage. These measures may be based on demographic analyses, comparisons with administrative records or estimations from a sample survey conducted shortly after the census. Both the Australian Bureau of Statistics (ABS) and Statistics New Zealand (SNZ) conducted a Post-Enumeration Survey (PES) following their respective censuses in 1996. How were these surveys designed and conducted? What can be learnt for the 2001 PES which follows the next five-yearly census in each country?