Extracted from the Australian Parliament official web notes regarding Senate elections.
Determining the successful candidates
The essential features of the Senate system of election are as follows:
To secure election, candidates must secure a quota of votes. The quota is determined by dividing the total number of formal first preference votes in the count by one more than the number of senators to be elected for the state or territory and increasing the result by one. A quota cannot be determined until the total number of formal ballot papers is calculated, which means waiting until the statutory period (13 days) for the receipt of postal votes has passed.
Should a candidate gain an exact quota, the candidate is declared elected and those ballot papers are set aside as finally dealt with, as there are no surplus votes.
For each candidate elected with a surplus, commencing with the candidate elected first, a transfer value is calculated for all the candidate's ballot papers. All those ballot papers are then re-examined and the number showing a next available preference for each of the continuing candidates is determined. Each of these numbers, ignoring any fractional remainders, is added to the continuing candidates' respective progressive totals of votes. Surplus votes are transferred at less than their full value. The transfer value is calculated by dividing the successful candidate's total surplus by the total number of the candidate's ballot papers.
Where a transfer of ballot papers raises the numbers of votes obtained by a candidate up to a quota, the candidate is declared elected. No more ballot papers are transferred to that elected candidate at any succeeding count.
When all surpluses have been distributed and vacancies remain to be filled, and the number of continuing candidates exceeds the number of unfilled vacancies, exclusion of candidates with the lowest numbers of votes commences. Bulk exclusions are proceeded with if possible; otherwise exclusions of single candidates take place. Excluded candidates' votes are transferred at full value in accordance with their next preferences to the remaining candidates. Under certain circumstances the transfer of a surplus may be deferred until after an exclusion or bulk exclusion.
Step 5 is continued, as necessary, until either all vacancies are filled or the number of candidates in the count is equal to the number of vacancies remaining to be filled. In the latter case, the remaining candidates are declared elected.
In counting votes in a Senate election, if only two candidates remain for the last vacancy to be filled and they have an equal number of votes, the Australian Electoral Officer for the state or territory has a casting vote, but does not otherwise vote in the election.
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