Sequentially Shrinking Quota: Difference between revisions
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'''Sequentially Shrinking Quota''' ('''SSQ''') is a sequential [[Multi-Member System |Multi-Winner]] [[Cardinal voting systems |Cardinal voting system]] built on [[Score voting]] ballots. It is a modification to [[Sequentially Spent Score]] designed to limit cases of [[free riding|free-riding]]. <ref>https://forum.electionscience.org/t/a-compromise-between-vote-unitarity-and-thiele-pr-methods/420</ref> |
'''Sequentially Shrinking Quota''' ('''SSQ''') is a sequential [[Multi-Member System |Multi-Winner]] [[Cardinal voting systems |Cardinal voting system]] built on [[Score voting]] ballots. It is a modification to [[Sequentially Spent Score]] designed to limit cases of [[free riding|free-riding]]. <ref>https://forum.electionscience.org/t/a-compromise-between-vote-unitarity-and-thiele-pr-methods/420</ref> |
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== Definition == |
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All ballots initially start as having weight 1, and the quota is initially set at the Hare quota. |
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The score each ballot contributes to a candidate in a particular round is equal to the weight times the score given for the "weighted" variant, and min{Max Score*weight, score given} for the capped variant. If there is a candidate (or multiple candidates) who exceeds the quota, then the candidate with the highest score in this round is elected, and the reweighting step is applied. If no candidate meets the quota, then a smaller quota size is chosen so that if all of the previous reweighting steps are recalculated for this smaller quota size (maintaining the prior order of election), then one candidate will be able to meet the new quota. This candidate is selected next. |
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===== Reweighting Step ===== |
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Each round, a ballot loses weight equal to (Score contributed to the candidate elected this round / Max score) * (Quota / Total Score for that candidate this round). |
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== References == |
== References == |
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Revision as of 06:18, 27 January 2020
Sequentially Shrinking Quota (SSQ) is a sequential Multi-Winner Cardinal voting system built on Score voting ballots. It is a modification to Sequentially Spent Score designed to limit cases of free-riding. [1]
Definition
All ballots initially start as having weight 1, and the quota is initially set at the Hare quota.
The score each ballot contributes to a candidate in a particular round is equal to the weight times the score given for the "weighted" variant, and min{Max Score*weight, score given} for the capped variant. If there is a candidate (or multiple candidates) who exceeds the quota, then the candidate with the highest score in this round is elected, and the reweighting step is applied. If no candidate meets the quota, then a smaller quota size is chosen so that if all of the previous reweighting steps are recalculated for this smaller quota size (maintaining the prior order of election), then one candidate will be able to meet the new quota. This candidate is selected next.
Reweighting Step
Each round, a ballot loses weight equal to (Score contributed to the candidate elected this round / Max score) * (Quota / Total Score for that candidate this round).