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

[Juho]

On May 9, 2010, at 2:13 AM, Kevin Venzke wrote:

>> It's just me and some others that have said that margins
>> seems at least more natural than winning votes (not
>> necessarily ideal).
>
> Ok, good. I just want to be clear on who is saying this.

Are you saying that winning votes are more natural? (or better for  
some other reasons)

>>> 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 remember this approach being discussed but it's not how I  
> would
> do it. You wouldn't start with the margin: margin is a hybrid between
> the ratio and the absolute vote count.

Also margins counts the absolute vote count (but not those on the  
winning side but the difference between the A>B and B>A votes).  
Technically margins may be somewhere between two other approaches but  
historically it was probably not generated and seldom described this  
way.

> What you would do is say that
> 40:30 is 40+30 = 70, and 30:20 = 50. That, perhaps, is what WV wants  
> to
> be.

Hmm, if the number of voters with (non-equal) opinion on the A vs. B  
comparison would add the preference strength then those votes that  
support the losing side would contribute negatively to the strength of  
the defeat of their favourite (in a non-monotonic way).

> On the other hand, maybe WV just wants to respect majorities expressed
> over majorities that can only be calculated to exist due to vote
> splitting. The "abstain" could mean "don't count my vote when  
> looking for
> majorities."
>
> "Abstain" could mean "detract from the importance of the contest."
> This is important when the race is over when voters decide whether the
> method respected the most important contests.

Winning votes have some characteristics in this direction but I don't  
have any short nice description of what it does. If there are many  
ways to interpret equal rankings and truncations maybe one could have  
methods where the voter can explicitly indicate in the ballot if then  
intention is to say "I don't know", "absolutely equal", "I don't  
care", "abstain", "not an important defeat" etc.

>> 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").
>
> Suggest another rule that respects majorities.

Doesn't margins do so?

>>> 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.
>
> I would say that's because it's difficult to understand what it  
> refers to.
> Sometimes people write criteria to say how a method should behave,
> without direct reference to strategy, such as Condorcet, Plurality,
> Smith, or CDTT. I don't know what the margins standard is other than
> that its resolution rule can be explained in few words. Even the  
> notion
> that an equal ranking should be treated as a split, self-opposing vote
> seems to be based in strategic concerns.

I often divide the discussion about various criteria in two parts.  
Those criteria that deal with which candidate should be elected with  
sincere votes and those that address the problems with strategies.

To me the description of minmax(margins) (that uses directly the  
concept of margins) as "elect the candidate that needs least  
additional votes to win all others" is at the same time both an exact  
definition of the method and a description of who would be the ideal  
winner. According to this philosophy one should elect the candidate  
that would face least opposition after being elected (by people that  
would have preferred some candidate X to the winner and could join  
forces to oppose try to harm the elected winner). I think there are  
many kind of elections where the used criteria to determine the  
optimal winner may be different. This philosophy is thus not the only  
possible philosophy but it is certainly one that could be considered  
even ideal in some/many single-winner elections.

>> I wonder if someone has somewhere written a description on
>> how winning votes is intended to measure sincere opinions.
>
> You already did. You observed that WV advocates tend to see a  
> different
> meaning to truncation. This is a different concept of sincerity that  
> WV
> accomodates.

I think I mentioned all the components that you refer to but I didn't  
find yet a description and understanding that I would call natural.  
I'm also always a bit confused about the truncation related rules and  
criteria since the calculation rules treat truncations and other equal  
rankings exactly the same way (i.e. technically there is no difference  
between these two).

> When I run simulations and I see a bullet vote "A" to me this does not
> mean "A>B=C" due to the fact that in a public election that  
> interpretation
> would be presumptuous and unrealistic.

This is confusing to me in the winning votes argumentation since  
technically equal rankings and truncations are handled the same way.

> If the setting were different, where voters are supposed to be
> knowledgeable about all the candidates and vote the whole ranking  
> whether
> they want to or not, and it could be expected that the voters would
> never be torn on whether to use strategy or risk giving the election
> away (I say "strategy": in the form of burial this could have a  
> defensive
> or offensive intent in margins, and that's why I think it's a big  
> problem
> to remove truncation as an option) then I might have a use for the
> margins standard of sincerity.

As long as we are talking about pure ranked ballots I tend to see all  
equal rankings as equal rankings. They can be allowed in all forms  
(truncation and other). If we should read some additional meanings  
from the ballots that should be clearly defined.

>
>> 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?
>
> As long as A loses I don't care that much. If voters care so much  
> about
> a 2% difference in FPs then we are generally in trouble. (What  
> principle
> does margins adhere to that prevents this from being a problem in
> general?) And not even half of the A voters supported B.

If A represents the left wing then the left wing voters said "we  
prefer B to C if right wing gets majority and one of their candidates  
wins". In the left wing there were more voters that didn't maybe care  
or found all the right wing candidates to be equally bad than in the  
right wing. That is natural. Within the right wing B seems to be  
clearly more popular than C, so the right wing agrees with the left  
wing that B is better than C. The only remaining tricky part is that  
the votes are cyclic. Can we derive some such logic from that cycle  
that C should win instead of B?

> The public needs to ask themselves what A>B=C means. They should  
> have a
> look at those ballots. (Really I would say it's only fair for  
> truncation
> to be completely banned in margins, except that I think that people
> truncating without meaning to say "all the worst candidates are  
> exactly
> equal" would actually be causing less damage than if we forced them to
> come up with something.)

I'm ok with margins and equal rankings (also other than truncation).  
Truncation due to not knowing enough or due to considering all the  
remaining candidates to be more or less equal are quite good and  
sincere reasons to truncate. Truncation due to laziness may lead to  
distorted results (since all opinions are not measured). Truncation  
due to fear of supporting the competitors of one's own favourites by  
ranking them in one's ballot is usually a misunderstanding. There are  
also some cases where truncation could be related to strategic  
behaviour but in large real life elections this is hopefully marginal  
and mostly not rational.

Juho