Cardinal voting systems: Difference between revisions
→Single Member systems: Added section on "Determining relative accuracy or utility between voting methods." Moved Bayesian Regret paragraph to this section and added a paragraph on VSE. Included STAR Voting in summary findings in this section and added note that STAR was not tested in BR. Fixed "runn-off" typo in single winner chart and made Bayesian Regret capitalization consistent.
Dr. Edmonds (talk | contribs) No edit summary |
(→Single Member systems: Added section on "Determining relative accuracy or utility between voting methods." Moved Bayesian Regret paragraph to this section and added a paragraph on VSE. Included STAR Voting in summary findings in this section and added note that STAR was not tested in BR. Fixed "runn-off" typo in single winner chart and made Bayesian Regret capitalization consistent.) |
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[[Cardinal voting]] is called [[Score Voting]] when a sum or average is used to tally votes to find the [[Utilitarian winner]]. It is typical to use a sum. Averages will give a differing result in systems where there is a no opinion option for each candidate meaning that the average is done over a differing number of voters for each candidate.
[[Score voting]] has the lowest [[Bayesian Regret]] among all common single-winner election methods. [[Bayesian regret]] is a measure of how the second order consequences of using a system affects the population. It can be thought of as the quantifiable amount of “expected avoidable human unhappiness.” It draws its merit from utilitarianism which intends to optimize for the total amount across the population. This is opposed by the theory of majority rule which intends to optimize only for the majority.▼
The median can also be used to aggregate a cardinal ballot in Majority judgment systems. The use of the median is intended to further diminish the effects of strategic voting. Majority judgment voting satisfies the majority criterion, stated as "if one candidate is preferred by a majority (more than 50%) of voters, then that candidate must win". It should be noted that [[Instant-runoff voting]] also satisfies this criterion. While it might sound like this is always a good requirement of a voting system, consider a polarized scenario where 51% prefer one candidate and hate the other while the remaining 49% is just the opposite. If there was a third candidate who 100% would be satisfied with they would not be elected in a system which satisfied the majority criterion. Satisfying the majority criterion reduces incentive for compromise and raises Bayesian Regret.
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It is worth noting why [[Approval Voting]] does not lead to a tyranny of a centrist majority situation. There is difference between a tendency towards a moderate or compromise candidate and a majority candidate. For example, if there is a small group in desire of representation then the candidates would gain approval if they could add the desires of this group to their platform. This means issues that are neutral to the centrist majority and highly relevant to a small group are important for candidates to understand. Additionally, if the overlap of votes is released then the candidates can study the results to determine which candidates represented an isolated group. For example, if there were a candidate who only received votes because of a particular issue, then all candidates would be wise to integrate this issue into their platform for the next election to be more competitive. However, a case can be made that candidates are incentivized to make promised to special interest groups which benefit the few a lot but do not hurt the majority enough for them to get mobilized. In many instances, like with tax code, this effect lowers the total prosperity of the society at large. This effect certainly exists in other systems and it has not been empirically shown that it is more problematic in Approval Voting.
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== Determining relative accuracy or utility between voting methods ==
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[http://electionscience.github.io/vse-sim/VSE/ Voter Satisfaction Efficiency] (VSE) is a newer model which has been used to evaluate voting method utility. VSE is an inverse of Bayesian Regret, with higher scores representing better utility. STAR Voting was found to have the highest Voter Satisfaction Efficiency rating overall.
== [[Single Member systems]] ==
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| [[Approval Voting]] || [[Utilitarian winner | Sum]] || [[Approval Voting | Binary]]
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| [[STAR voting]] || [[STAR voting | Sum, then top two
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| [[Median Ratings]]|| Median || > 2
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