[EM] IRV vs Plurality (or is it about Range? maybe it should be about Condorcet.)

[robert bristow-johnson]

On Jan 28, 2010, at 3:12 PM, Juho wrote:

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

i think there are ways of not encouraging strategic voting by not  
punishing sincere voting.  i'll defer to Arrow and the common wisdom  
here that ultimately no system completely ditches strategic voting  
under all conceivable conditions.

>>> 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.

i actually don't think it's so good.  i was just trying to point out  
one of the main problems i see with Range.

>> 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.

and, again, my point is that with my secret ballot, and my suspicion  
that political opponents may well be voting with exaggerated ratings,  
that *i* would feel pressured to exaggerate *my* preferences and that  
i might expect *any* savvy voter to do the same.  then, if everyone  
does that, the continuous gradation of Range loses its meaning.

>>> 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.

i think that we should expect political opponents to strategize on  
how to defeat their opponents in any society.

>> 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,

i don't see how it would be with a simple ranked-order ballot.   
especially, if decided by Condorcet, you cannot exaggerate your  
rankings.  if you like A better than anyone and you like B better  
than C, then there is nothing to be gained by any other ranking than  
A>B>C.  if you really hate C, you can rank a bunch of other  
candidates you don't care about between B and C.  but it doesn't  
change how the election would work between the candidates A, B, and C.

> 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).


and again, in a response i made long ago to Warren Smith, i think the  
best system is one that assumes that, if there is anything to be  
gained by voting strategically, that voters will be doing that, and  
the best system would not predictably reward such strategic voting.   
then there is nothing to gain by not voting sincerely.

--

r b-j                  rbj at audioimagination.com

"Imagination is more important than knowledge."