Vote unitarity: Difference between revisions

→‎Creation: Expanded on initial motivation
(Added point on how sequential PR methods run on a sort of continuum from Bloc elections to SSS and beyond.)
(→‎Creation: Expanded on initial motivation)
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==Creation==
 
Since [[Single Transferable Vote]] allocates voters it violates vote unitarity by over removing influence in some cases. This occurs in all allocation systems; for example in [[Allocated Score]] somebody who only gave a score of 1 to the winner could lose all future influence. [[Reweighted Range Voting]] on the other hand only reduces influence fractionally so a voter who got a candidate they gave max score in the first round theywould only have their ballot weight is reduced to 1/2. This violates the principle of one person one vote since this person would essentially be allowed to vote with half weight in later rounds (note that if a Bloc Score election is treated as a sequential method, then every time a candidate is elected, a voter who got one of their max-scored candidates is actually allowed to vote with full weight in later rounds, Thiele methods such as RRV are more proportional than Bloc elections because they at least reduce ballot weight to some degree). Proponents of [[Single Transferable Vote]] would use this argument for its superior fairness over [[Reweighted Range Voting]]. and the [[KeithReweighted EdmondsRange Voting]] wanted to design a score reweighting system which had neither of these flaws. As such it would preserveuse the amountopposite of score used through sequential roundsargument. He was also unhappy withSince [[AllocatedReweighted ScoreRange Voting]] since somebody who only gave a score of 1 to the winner could lose all future influence.and [[SequentiallySingle SpentTransferable ScoreVote]] isare thevery sequentialpopular [[Multi-Membersystems Systemwhich |violate Multi-Winner]]Vote [[CardinalUnitarity votingin systemsopposite |ways Cardinalit votingshould system]]be builtpossible onto [[Scorefind voting]]a ballotsbalanced tomiddle followground. this principle.
 
On an even further extreme, [[Bloc voting]] when treated as a sequential method often violate Vote Unitarity even more than [[Reweighted Range Voting]] since a voter can fully influence the election of multiple candidates independently without any reweighing. [[Cumulative voting | Cumulative Voting]] attempts to mitigate this by giving voters the same amount of vote beforehand with the understanding that it is up to them to chose how to reweight on their ballot. This also has the added effect that makes outcome of [[Cumulative voting | Cumulative Voting]] have higher [[Proportional representation]] than standard Bloc Systems. Thiele methods such as [[Reweighted Range Voting]] violate Vote Unitarity less than Bloc elections because they at least reduce ballot weight to some degree. In addition they do this reweigting in such a way to satisfy the Hare Quota Criterion.
 
[[Keith Edmonds]] saw a unification of [[Proportional representation]] and the concept of one person one vote. He coined the term "Vote Unitarity" for the second concept and designed a score reweighting system which satisfied both Hare Quota Criterion and Vote Unitarity. As such it would preserve the amount of score used through sequential rounds which attributing representation in a partitioned way. It would assigne Hare Quotas of score to winners which allowed for a voters influence to be spread over multiple winners. The final system was originally proposed in a late stage of the [[W: 2018 British Columbia electoral reform referendum]] but was not selected for the referendum ballot. This system, [[Sequentially Spent Score]], was the first sequential [[Multi-Member System | Multi-Winner]] [[Cardinal voting systems | Cardinal voting system]] built on [[Score voting]] ballots to satisfy Vote Unitarity. Variants were soon found.
 
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