PR-STV is the Single Transferable Vote (STV) form of Proportional Representation (PR). A key benefit of PR-STV is that all representatives are directly elected by the people.
PR-STV is an electoral system that has multi-member electorates in which the percentage of the total votes in each electorate that is required to elect each successful candidate (after any distribution of preferences of surplus votes or votes of candidates excluded during the count) is as close as practicable to the percentage that each member is of the total number of members representing that electorate. That percentage, the quota, is set such that the residue of votes after all quotas have been used to elect the prescribed number of candidates is just below a quota.
PR-STV is used in Australia:
- Senate (Australia’s Senate is the largest scale use of PR-STV in the world)
- Victoria’s Legislative Council
- Tasmania’s Legislative Assembly
- ACT’s Legislative Assembly
- Victoria’s Local Councils, including the City of Yarra
Every bicameral Australian parliament now has a house with a PR-STV electoral system.
PR-STV is also used for the lower houses of Eire and Malta, the elections by State legislators for the upper house of India entrenched in Article 80(4) of the Constitution of India, and only one remaining U.S. municipality, Cambridge, Massachusetts.
Countback and Robson Rotation enhancements to PR-STV
The PRSA’s letter to Victoria’s municipal councils of 21st August 2003 urged them to call on the State Government to introduce the important additional features of Countback and Robson Rotation, which greatly enhance the Hare-Clark PR-STV systems used in Tasmania and the Australian Capital Territory for the elections of their legislatures and municipal councillors, but are absent in New South Wales and South Australia.
A good background to the use of PR-STV (quota-preferential PR) is the history page on the PRSA website.