[EM] Meta-criteria 6 of 9: Heuristics. #1, simplicity

[Juho]

On May 8, 2010, at 6:32 AM, Kevin Venzke wrote:

> Hi Juho,
>
> --- En date de : Ven 7.5.10, Juho <juho4880 at yahoo.co.uk> a écrit :
>>> *Who* must have considered winning votes to not be
>> optimal with sincere
>>> votes?
>>
>> I don't really know what others have thought. My first
>> approach when I first time thought about pairwise comparison
>> based methods was that margins would be a natural and simple
>> way to measure preference strengths, and I needed an
>> explanation to why one would use wining votes. The
>> argumentation that I found was related to strategic voting.
>>
>>> Never mind that you noticed above that WV advocates
>> tend to have a
>>> different conception of truncation. (Though I wouldn't
>> call it
>>> disapproval; disapproval is likely, but the point is
>> abstention.)
>>>
>>> The arguments I remember are about majorities and
>> sincere CWs more than
>>> about fixing strategic incentives for its own sake.
>>
>> There have been arguments that the reason why margins is
>> not good is its strategic vulnerabilities when compared to
>> winning votes. (This means that winning votes have been
>> considered to be better because of strategy related reasons.
>> But this doesn't say anything on if someone finds winning
>> votes to be ideal with sincere votes.)
>
> And it doesn't say anything on whether someone finds margins to be  
> ideal
> with sincere votes.

It's just me and some others that have said that margins seems at  
least more natural than winning votes (not necessarily ideal).

>
> What *does* mean that WV is considered to be better with sincere votes
> is the perspective that when voters truncate they mean to abstain, and
> not lend weight to the ignored contests.

What does "abstain" mean? Margins thinks that 40-30 and 30-20 opinions  
are of same strength. Should we consider the strengths of those  
opinions to be (40-30)/70 and (30-20)/50? Now we treat the truncated  
and equal rankings in some sense as abstentions. This approach has  
also been discussed but it is not winning votes. With this approach  
opinion 30-20 is stronger than 40-30 (unlike in winning votes). It  
differs from margins in that it counts how much stronger the winning  
side is in percentage (not in number of votes as in margins).

I don't have any better explanations to winning votes as the ideal way  
to measure preference strengths (better than "number of votes on the  
winning side against some other candidate").

>
>>> FPP has strategic problems beyond those found in
>> IRV... We don't conclude
>>> from this that FPP is better with sincere votes. We
>> don't take arguments
>>> about FPP's strategic problems as an admission that
>> "otherwise" (???) FPP
>>> was just fine.
>>>
>>> Why couldn't I say that the point of *margins* is to
>> minimize a strategic
>>> incentive?
>>
>> There are cases where margins are less vulnerable to
>> strategic voting than winning votes but I don't recall
>> anyone saying that margins would have been designed with
>> this in mind.
>
> I'm talking about truncation here, and the way margins makes it  
> useless.

I think the margins philosophy is that truncations and equal rankings  
are both treated as equal rankings. Or do you mean that truncation  
should be interpreted as some kind of "implicit approval cutoff"?  
Should "A=B>C" be treated differently than "C>A=B" or "C" with respect  
to the pairwise comparison between A and B? Or do you refer to  
truncation as a strategic defence mechanism?

>
> My point is more that I don't know of any coherent explanation of why
> margins is "ideal" with sincere votes, and WV is not. But that  
> explanation
> must be out there if the only problem WV advocates have with margins  
> is
> its strategic incentives. There must be some 10+-year-old posts from  
> WV
> advocates unhappy that they can't just use margins.

There are many mails and web articles. But maybe less on the  
performance with sincere votes than about strategies. At least  
according to my experience it is difficult to raise good quality  
discussion on that very central topic.

>
>>> Considering that you just complained about the
>> potential
>>> strategic implications of the WV view of truncation.
>>
>> I mentioned at least the possibility of message "truncation
>> = approval" possibly leading to shorter than fully ranked
>> votes.
>>
>>> Schulze and WV are only not focused on minimizing the
>> number of
>>> "eliminated" ballots in the narrow sense that you pick
>> out to support
>>> margins. Practically the whole point of WV is to be
>> able to ignore the
>>> smallest number of preferences that were actually
>> specified, rather than
>>> imagined.
>>
>> With 100 voters opinion 40-30 means that there are 30
>> no-opinions or equal opinions. Margins seems to assume that
>> the (from 0 to 30) no-opinions are either equal opinions or
>> 50%-50% in both directions. One could also assume that every
>> truncated vote and vote that contains equal rankings is
>> intentionally created by the voter and therefore the voter
>> intentionally wants these candidates to be considered equal.
>> Winning votes seems to assume that no-opinion and equal
>> opinion correspond to voting against the pairwise winner
>> since 40-30 and 40-0 have the same meaning.
>
> That is ridiculous. What can "correspond" mean when adding votes  
> against
> the pairwise winner can make him the pairwise loser?

Yes, the rules are asymmetric in the sense that the description of the  
strength of the defeat changes depending on which one of the  
candidates wins.

>
> I guess what you mean to point out is that WV actually does ignore a
> type of preference actually expressed. Fair enough, but it doesn't  
> matter
> to my point, which is just that WV actually does have logic that has
> a resemblance to - and is as completely arbitrary on a purely  
> aesthetic
> level as - the principle of adding/removing as few ballots as  
> necessary
> to create a CW.

I wonder if someone has somewhere written a description on how winning  
votes is intended to measure sincere opinions.

Juho



P.S. My biggest fears with winning votes is that it might in some real  
elections (with sincere votes) produce a result that people do not  
find natural.

10: A>B=C
20: A>B>C
16: A>C>B
01: B>A=C
01: B>A>C
26: B>C>A
03: C>A=B
03: C>A>B
20: C>B>A

This set of votes is cyclic. B and C are from the same wing (they  
support each others). But should C win (as in most methods with  
winning votes) although B has more first preferences than C and also A  
supporters like B more than C?



>
> Kevin Venzke
>
>
>
>
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