[EM] Truncation (was re: Defeat Strength)

[Juho Laatu]

Your approach seems to be close to the tradition of voters estimating the utility of each candidate, and then putting them in linear order, based on those identified utilities. That is a good approach. No chances given to influence the elections any more than that. Everyone understands that approach, and can vote accordingly with full strength of one's vote.

The "unmarked treated as equal last" rule could be seen as adding to this the idea that all given opinions should be positive and not negative. The unmarked candidates must thus be at zero level. (There are also other, more practical reasons behind the "equal last" practice. It may be good not to give totally unknown candidates any "unearned" points.)

One could indeed "force" voters to always rank all the marked candidates (i.e. explicitly marked ties not allowed) without losing much. There is always a small difference, and if not, one can always flip a coin. In some ballot formats equal rankings are natural, and in some others unnecessarily complex.

I don't actually see any practical benefits in the "A B" approach or other "no opinion" additions . It is an interesting theoretical area of study to see what kind of additional information we could use (up to free form algorithms), but for large competitive single winner elections with independent voters the basic approach of ranking + "equal last" seems to be a stable basis. (Different strength preferences (A>>B>C) might be useful somewhere - or seriously - maybe not really :-) .)

(Different defeat strength measurements may treat those pairwise ties in different ways, but that's another story.)

Juho


> On 11. Sep 2022, at 16.22, Kristofer Munsterhjelm <km_elmet at t-online.de> wrote:
> 
> On 11.09.2022 13:40, Juho Laatu wrote:
>> Hi,
>> I noted discussion on if "not marked in the ballot" should mean
>> "equal last" or "no opinion". Does someone have an opinion on if also
>> "equally good" (explicit or implicit "A=B") and "no opinion"
>> (explicit or implicit "A B") should be seen as two different
>> opinions? One possible difference in meaning is "if A is about to get
>> elected, also B should be about to get elected" vs "I don't care at
>> all if one or both of them are elected or not".
> I consider those to be roughly equivalent. What equal-rank means to me is something along the lines of "with the time I've given myself, I can't see a difference between these candidates, and I think it's more worthwhile for other ballots to decide".
> 
> Unless two candidates are identical, every voter probably has an ever so slight preference between the two that he could discover given enough effort. But a voter equal-ranking simply says that it's not worth it. (It's sort of related to the idea of the absolute threshold or JND.)
> 
> -km