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STV counting methods - a summary of the most common methods
Although the basic format of an STV election is the same everywhere, the exact mechanics of the count vary. Differences are most often found in the way in which surplus votes are transferred. This page lists the most common methods and the differences between them. The Republic of Ireland system Under this system surplus votes are transferred at random. Only the last packet of votes received is considered when selecting the votes to transfer. If a surplus arises from first-preference votes only, then the surplus is distributed in proportion to the second preferences, but the specific votes transferred are selected at random. The Northern Ireland system The mechanism for counting votes in Northern Ireland is also known as Newland-Britton or Gregory. Scotland has decided to elect its local councils using STV and has decided to use the Northern Ireland counting rules. The Northern Ireland counting rules are similar to those in the Republic in that only the last packet of votes received is used when transferring surplus votes. However, the all non-transferable votes are transferred at a fractional value. For example, if X received 500 votes putting him 50 votes over the quota, then each of the 500 votes is transferred at 50/500 of its original value. The "Inclusive-Gregory" system This system is used in some elections in Australia. In this system, all a candidate's votes are considered when performing a surplus. Votes that a candidate received with a fractional value are considered whole votes for the purpose of transferring votes. All votes are transferred at a fractional value. This system is not logical, in that votes received at a fractional value are given the same weight as full votes. The "Weighted-Inclusive-Gregory" system This system may not actually be used anywhere, but it is the system that the Dept. of the Environment intends to introduce here if electronic voting is fully implemented. In this system, all a candidate's votes are considered when transferring a surplus. All votes are transferred at a fractional value. Votes that had been received at a fractional value are at a fraction of the fractional value. For example, if the quota is 9500, and X has 10000 votes, a surplus of 500 votes. All X's 10000 votes will be transferred at a fractional value of 500/10000. If 100 of X's 10000 votes had originally been received with a fractional value of 1/10 then these votes would transfer to their recipients with a fractional value of 500/100000. The "Meek" system This system is used in some New Zealand local elections. This system is similar to the Weighted-Inclusive-Gregory method but also reduces the quota and re-runs the counts whenever votes become non-transferable. The Meek system requires the count to be conducted by computer. The "Weighted-Inclusive-Gregory" system is also unlikely to be used without the aid of computers because of the length of time a count would take. The introduction of computers carries its own risks - how democratic is a system if the result cannot be determined by ordinary voters? There are other variations that can be introduced - for example, the Electoral Reform Society rules for counting STV elections by hand suggest that the quota should be reduced if votes become non-transferable before any candidates have been elected. STV is again increasing in popularity. Scotland and New Zealand have introduced it for local elections. Wales is very likely to follow. British Columbia is to have a referendum on whether to introduce STV next May. The wider use of STV may introduce new variations to the counting process. |
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