The AEC determines the number of members to which each state and territory is entitled, which is based on the population of each state and territory. The Australian Bureau of Statistics officially provides to the AEC its estimate of the population for each state and territory for a year after the first sitting day for a new House of Representatives, termed "ascertainment". Based on these figures, the AEC makes its apportionment determination one year and one day after the first sitting day for a new House of Representatives. A redistribution is postponed if it would begin within one year of the expiration of the House of Representatives, to prevent a general election from occurring while a redistribution is in progress.