STLR voting: Difference between revisions
typeos and examples
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'''STLR voting''' (pronounced 'Stellar Voting') is an [[Voting method|electoral system]] [[:Category:Single-winner voting methods|for single-seat elections]], though it can be extended to a [[Multi-member system]] with a sequential elimination method. The name stands for "score then levelled runoff", and can be thought of as a [[Utilitarianism | utilitarian]] version of [[STAR voting]]. It is a type of [[cardinal voting]] electoral system and while the name is a clear reference to [[STAR voting]] it is actually a compromise between [[STAR voting]] and [[Score voting]].
Voters cast ballots as in [[Score voting]], rating each candidate from 0 to a maximum value, <math>MAX</math>. The two candidates with the highest total are selected as finalists, and then in the "levelled runoff" a winner is chosen. In the runoff the scores are levelled such that the higher of the two
==Method==
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# The scores for each candidate are then summed
# The two candidates with the highest sums go to the runoff.
# On each ballot, the scores of these two are levelled by multiplying
#:* Explicitly, if the scores for the candidates are <math>a</math> and <math>b</math> then they are levelled to <math> a_{new} = a \frac{MAX}{max(a,b)}</math> and <math> b_{new} = b \frac{MAX}{max(a,b)}</math>
# The levelled scores for each candidate are then summed and the winner is the one with the higher sum
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The concept was invented by [[Equal Vote Coalition]] Director [[Keith Edmonds]] and was first proposed publicly in July 2020<ref>{{Cite web|url=https://forum.electionscience.org/t/a-new-star-variant/708/28|title=CES Forum Post|last=|first=|date=|website=|url-status=live|archive-url=|archive-date=|access-date=}}</ref>.
The originally proposed runoff
=== Scale in Score Voting ===
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=== Problem of being Majoritarian ===
STAR is intended to be a compromise between [[score voting]] and [[instant runoff voting]].<ref>{{Cite news |url = http://equal.vote |title = Equal Vote Coalition |work = Equal Vote Coalition |access-date = 2017-04-05 }}</ref>. It solves the above issue of scale because as long as a preference is shown between the two candidates in the runoff, then their influence is maximized. It is a majoritarian system as shown in the example
<poem>Red 51%: A[5] B[4] C[0] D[0]
Blue 49%: A[0] B[4] C[0] D[5]</poem>
It elects A when both Score and Approval voting elect B. B is a compromise and the [[Utilitarian winner]]. STAR argues that it is better because it recovers the way that people would have voted given the top two utilitarian winners.
One can still solve the scale problem in score voting without resorting to majoritarianism with a different normalization before the runoff. STAR puts the favoured candidate to
In summary, the favoured candidate is levelled up to <math>MAX</math> so that all voters have the same maximum endorsement of the preferred candidate in the runoff. The less preferred candidate is given the same scaling so that the relative utility on the ballot is preserved. This means that the [[Utilitarian winner]] will be chosen in a runoff where each voter has equal influence.
==Examples==
An example was already given above showing that STLR voting is indeed Utilitarian. There are other situations where this helps vs either STAR or score.
===Losing favourite===
Suppose a voter in a [0,5] system gave candidates A, B and C the following scores; A:5, B:1, C:0. Clearly A is their favourite and they have expressed this. However, if A is unviable and the top two are B and C they have ruined their influence by giving B only a score of 1. Proponents of score voting arbgue that an informed voter should know the polling data and vote strategically as A:5, B:5, C:0. This is wrong for two reasons. Firstly, incentive to vote dishonestly should never be encouraged. Secondly, polls can be wrong or manipulated. If B was supported by the media then they could have their standing inflated so that people would vote for them as a lesser evil. In both STLR and STAR voting. The runoff between B and C converts the ballot to B:5, C:0 without any need for the voter to vote strategically.
=== Preserving Utility===
Suppose a voter in a [0,5] system gave candidates A, B, C, D and E the following scores; A:5, B:4, C:2, D:1, E:0. If the runoff come to A and B STLR voting leaves the scores as is since one is already at <math>MAX</math>. However, STAR would convert them to A:5, B:0 which greatly exaggerates the voters preference between A and B.
If the runoff comes to C and D then STLR voting levels it to C:5, D:5*1/2=2.5. The impact on the final sum is 5-2.5 = 2.5. The impact from the score method would be 2-1=1 so significantly smaller. The impact in the STAR method is always 5 so significantly larger.
The voter themselves would always want their impact maximized but they also do not want tyranny of the majority. STLR finds the middle ground. No matter who is in the runoff the voter has their score levelled in a fair manner.
==Sequential elimination System==
STAR is basically [[
A similar sequential elimination method can be made by eliminating the worst candidate then applying the levelling to all remaining candidates. A [[Multi-member system]] can be made from this by stopping while there are still multiple candidates remaining.
This puts this new system in a class of systems with [[
==References==
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