Estimating the Count Error in the Australian Census

In many countries, counts of people are a key factor in the allocation of government resources. However, it is well known that errors arise in Census counting of people (e.g., undercoverage due to missing people). Therefore, it is common for national statistical agencies to conduct one or more “audit” surveys that are designed to estimate and remove systematic errors in Census counting. For example, the Australian Bureau of Statistics (ABS) conducts a single audit sample, called the Post Enumeration Survey (PES), shortly after each Australian Population Census. This article describes the estimator used by the ABS to estimate the count of people in Australia. Key features of this estimator are that it is unbiased when there is systematic measurement error in Census counting and when nonresponse to the PES is nonignorable.