Every few years, federal and state electoral commissions conduct boundary redistributions, where the borders of electorates in a state are redrawn, either to reflect a change in the number of seats in the parliament, or to standardise the number of electors in each district.
When a redistribution occurs, electoral analysts use the results from the previous election to estimate what the results would have been had the new boundaries been in place at that election. The two-candidate-preferred margins can change significantly, and seats can even be notionally held by another party.
This presentation will show how the ABC's Antony Green and other psephologists use geographic and electoral data to calculate new electorate profiles following a redistribution, using real examples from previous elections and redistributions.