Concept
The single transferable vote (STV) is a proportional representation voting system that elects multiple winners based on ranked voting. Under STV, an elector's vote is initially allocated to his or her most-preferred candidate. Candidates are elected (winners) if their vote tally reaches quota. After this 1st Count, if seats still remain open, surplus votes are transferred from winners to remaining candidates (hopefuls) according to the surplus ballots' next usable back-up preference. if no surplus votes have to be transferred, then the least-popular candidate is eliminated so the vote has chance to be placed on a candidate who can use it. The system minimizes "wasted" votes and by ensuring that each successful candidate was elected with the same (or close to the same) number of votes, the system produces approximately proportional representation without the use of party lists. A variety of algorithms (methods) carry out these transfers. When using an STV ballot, the voter ranks the candidates on the ballot. For example: Some, but not all single transferable vote systems require a preference to be expressed for every candidate, or for the voter to express at least a minimum number of preferences. Others allow a voter just to mark one preference if that is the voter's desire. The quota (sometimes called the threshold) is the number of votes that ensure the election of a candidate. Some may be elected without quota but any candidate who receives quota is elected. The quota must be set high enough that the number of elected candidates cannot exceed the number of seats, but the lower it is, the more fair to parties - large and small - the election result will be. The Hare quota and the Droop quota are the common types of quota. Generally, quota is set based on the valid votes cast, and even if the number of votes in play decreases through the vote count process, the quota remains as set through the process. Meek's counting method recomputes the quota on each iteration of the count, as described below.