[EM] IRV vs Plurality (or is it about Range?)

[Juho]

On Jan 28, 2010, at 8:20 PM, robert bristow-johnson wrote:

>
> On Jan 27, 2010, at 6:55 PM, Juho wrote:
>
>> On Jan 27, 2010, at 11:47 PM, Jameson Quinn wrote:
>>
>>> Without the uneven strategy problem, "full-blown Range" would be,  
>>> hands down, the best (single-winner) voting system possible
>>
>> Would you be happy with fixed range ballots (e.g. 0 - 99) or should  
>> one allow any integer to be used ( -infinity - infinity )?
>
> :-)
>
>> If one uses a fixed range should all voters then normalize their  
>> ratings (worst=0, best=99) or use a narrower scale (e.g. worst=40,  
>> best=85) if their feelings about the candidates are not very strong?
>
> :-)
>
> implicit to that question is what voters, who bother to come to the  
> poll to express their opinions/wishes, would voluntarily reduce  
> their influence by narrowing their ranges of approval.  who comes to  
> the polls without a desire to support a favorite candidate?  if they  
> do not wish to reduce their influence, what will they do with  
> Range?  i think nearly every voter will have a 99 and at least one  
> 0.  otherwise, they leave the poll thinking they threw part of their  
> vote away.
>
>> Should one determine some reference points for the voters (e.g.  
>> less than 10 = not accepted, 90 = excellent) to make sure that the  
>> given ratings are comparable? (this is more important if the range  
>> is infinite)
>
> :-)
>
> no, i think that if i can think up a negative number with greater  
> magnitude than anyone else, i should be able to single-handedly  
> scuttle a popular candidate.

Ok, you seem to think that one can not get rid of strategic voting in  
typical (political I guess) elections. Same with normalization and  
probably also exaggeration in Range. (Normalization could also be  
sincere in the sense that the society might recommend all to normalize  
in order to make all votes a bit more equal.) I agree that this is  
very caracteristic to political elections that tend to be more or less  
competitive when arranged by us humans.

(I note that normalization may not be enough. My sincere normalized  
opinion is A=100 B=75 C=0. Then someone introduces intentionally a new  
candidate that others find quite ok but that I strongly dislike.  
Should I vote then A=100 B=95 C=80 D=0? I think they did that on  
purpose! (the normalization tendency can be used strategically) So  
maybe I'll vote A=100 B=75 C=0 D=0 if I don't believe the leading  
candidates are C and D.)

>
>> Is the sum of votes (or average) really what one wants or should  
>> one aim at providing about equal results to all, or maybe try to  
>> keep the worst results to individual voters as high as possible  
>> (40,40,40 vs. 0,60,60)?
>>
>> Would there still be electons where we would want to decide based  
>> on majority and breadth of opposition, or should all elections  
>> follow the "sum of utilities" pholosophy?
>
> maybe if we changed it from "sum of utility" (which is just a scaled  
> version of "mean of utility") to "median of utility".  that might  
> help prevent skewing by extremists that will plug their candidate  
> with 99 and every opponent with 0.  but if people all do that, Range  
> becomes Plurality.

That would be a good approach in a situation where most voters are  
sincere but we are afraid that some (small subset) of them might be  
strategic.

>
> this is the strategy problem of Olympic judges (say of figure  
> skating or gymnastics or something with 8 judges holding up cards  
> rating the performance).  there is a problem with adding sincere  
> ratings to insincere and exaggerated ratings.  *especially* with a  
> secret ballot where no one needs to own up to and justify their  
> exaggerated rating.

In ski jumping the practice is that the highest and lowest score will  
not be included in the sum of votes. This approach is somewhere  
between mean and median. Maybe it has some benefits of both. Judges  
come from different major ski jumping countries so often one of the  
judges has a temptation to vote strategically. Votes are public, so a  
strong bias will be visible.

>
>> My point is maybe that if we would get rid of the strategy related  
>> problems we would be well off but we might then move towards  
>> solving more detailed problems, performance with sincere votes and  
>> other problems that are just noise today. On the other hand we do  
>> have also (almost) strategy free environments/elections/polls today,

Strategy free elections are typically non-political. For example if I  
go to restaurant with some of my friends and we will vote what kind of  
giant pizza to order (using Range) then the votes might be sincere.  
One additional reason is that some of my friends might get angry to me  
and leave if my strategic voting gets too obvious. In politics the  
strength of this sincerity encouraging phenomenon is btw quite  
different in different societies.

>
> with the exception of the strategy called "compromising".  that  
> happens quite a bit when there are more than two candidates and  
> there are at least two candidates that go into the election nearly  
> evenly matched in pre-election polls.
>
> it's amazing that anyone touts Range as the most strategy free.  the  
> more handles one finds on a control device (think of the ballot as  
> such) or the more positions one can set the knobs to, the more one  
> has to strategize on how to control it to one's intent.

The basic Range strategy is unfortunately present in almost all  
elections, available to almost all voters and is easy to apply (if we  
see Range as a method where voters are supposed to give their sincere  
(non-normalized or normalized) opinions).

Juho




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