The preliminary estimated resident population (ERP) at 30 June 2001 is derived from Census counts of Australian usual residents at 7 August 2001 by:
1. adding an estimate of Australian usual residents missed at the Census, as determined by the Post Enumeration Survey (PES) and demographic methods;
2. adding an estimate of Australian residents who were temporarily overseas at the Census date, as determined by migration records; and
3. subtracting an estimate of population change during 1 July to 7 August 2001, as determined from births, deaths and migration records.