[EM] Scoring (was Re: OpenSTV 2.1.0 released)

[Juho Laatu]

On 22.9.2012, at 22.06, Michael Ossipoff wrote:

> 2. Your statement above implies that Symmetrical ICT doesn't choose as
> well as [...what?] when
> people rank sincerely. That statement requires specification of what
> method(s) choose(s) better than SITC under sincere voting, and why
> that is so.

Give me a description of who would be the best winner with sincere votes in the election that we talk about. Then one can tell what the best method with sincere votes is (or at least give some directions). I don't know what the philosophy of ICT and the other mentioned related methods is if we assume sincere votes. My understanding is that they have been designed to resist certan strategies, not only to pick the best winner with sincere votes. Therefore there must be another method that elects the best winner (based on the definition that you gave) more often than they do.

>> Some properties of methods that I don't like very much are: 1) truncation
>> based approval, since that encourages voters not to take position on which
>> one of the non-approved candidates should be elected (works against the
>> basic idea of ranked methods of collecting the sincere preferences),
> 
> Sure, you're expressing the ideal goal of rank-balloting. But surely
> you know that that goal is unattainable.

There are many ranked methods that do not have this property. (Same with point 2.)

> But remember that my question was: Ok, then what method chooses better
> than SITC under completely sincere ranking? And why do you say that it
> does?

See above.

>> Doctors have similar problems. Many medicines are far from harmless. Doctors
>> have to compare the risks of the disease and risks of the medicine. If the
>> medicine is likely to make more harm than help, it should not be used. This
>> means that one should deviate from the method that picks the best winner
>> with sincere votes...
> 
> ...which is _what_ method?

There are different best methods for different needs.

(In my text above I asked you to provide a definition of the best candidate. A simple Condorcet oriented definition could be e.g. "the candidate that requires least additional support/votes to beat any of the other candidates in a pairwise comparison/battle should be elected". This target could be selected because it gives one rational argument why the winner could be able to rule well (= only little bit of additional support needed (if any) to gain majority support for his proposals while in office).)

>> ...only if one is certain that otherwise the method would
>> give even worse results because of strategic voting.
> 
> ..even worse than what??

A method that has been modified to cope with strategies does not elect the ideal sincere winner always. But the corresponding sincere method could be even worse if strategic voting is rampant.

> You haven't said what are the bad results of
> SITC and ITC that we need to avoid.

See my first comments above. Their deviation from the ideal should become visible after one defines the ideal sincere winner.

>> Obviously you believe
>> that basic [unimproved] Condorcet methods would attract certain strategies to the extent
>> that those methods must be fixed. And I believe that in most societies it is
>> more likely that strategic voting will be marginal.

> Because I don't know what method you're referring to, of course
> there's no way to answer your expression of belief.

I referred to basic Condorcet methods. (Ranked Pairs, MInmax,...)

> ...aside from the fact that I make no claim to know what's true about
> more than 1/2 of all societies.

With "most" I wanted to say that I don't expect many societies to converge towards widespread strategic voting. I start from that assumption and I want evidence before deviating from that assumption.

>> I think I already said that the computations (from digitized ballot content
>> to results) could be checked either by anyone or by some nominated entities
>> (if ballot content is not published to protect privacy).
> 
> Sure, but how would you guarantee the accuracy and honesty of the
> digitization? ...The process that occurs between the time that the
> voter casts hir ballot, and the time when we have that digitized
> record of which you speak.

This is a very traditional process. Nothing new in it. I'll give an approximate description of the process in Finland. In the polling station there are many representatives from many parties, monitoring the process. The votes are counted (information collected) right after the election ends, again together on one table by multiple people from multiple parties. After that the votes are sealed and sent for storage. I don't recall any serious problems or complaints. With complex votes the process would take more time, and there could be a need to double check, but the principles would probably stay the same.

> Did the voter hirself make out a paper ballot? Or
> was it made electronically by a voting machine (presumably, but not
> necessarily based on the voter's voting)?

Use of paper ballots is the traditional and reliable method. Ballots that are printed by a machine are still theoretically quite safe, but in practice not quite at the same level.

> And, if the voter made out the paper ballot, then you've got millions
> of paper ballots, distributed around the country (our large country).

No need for transport around the country. They could as well be sealed and stored locally after ballot data has been collected. And maybe better so (to store them under the eyes of all the locals who don't want their opinins to be falsified).

> How do you propose to show them to anyone who wants to look at them?

I don't. For most EM experts the digitized information should be enough. A different procedure applies for the ballot digitalization.

> And, as I asked before, why do you want to be guessing and hoping,
> when it's possible to simply be rid of favorite-burial incentive?

There are numerous different threats, and we should minimize them, starting from the worst problems. Sufficient protection against favourite burial is needed, but 100% protection (against all possible strategic ballot sets) may well be too much. One need to defend only against practical threats. Same with all other threats.

>> I know at least one person that is inclined to bury and probably would bury
> 
> Then you know that the problem is genuine.
> 
>> :-).

Probably there are some random irrational strategic votes in every large election :-).

>> But don't take medicine
>> that harms you more than the disease.
> 
> Ok, so then tell us how ICT and Symmetrical ICT would do harm.
> 
> And tell us your proposal for a method that wouldn't.

Again, see the beginning of this mail.

>> How would you expect them to vote in the next IRV election? (you can assume
>> reasonably similar candidates)
> 
> The Republican leaders, and probably most Republican voters too, would say:
> 
> "Look what happened! You ranked sincerely, and thereby you let the
> Democrat be eliminated immediately, giving the win to the Progressive.
> That was your reward for sincere ranking.
> 
> "Next time, don't let that happen. Next time, rank the Democrat in 1st
> place, because otherwise the Progressive will win again."

My guess is that Republican leaders (in Burlington) would not make such a recommendation unless it would be very clear that the Republican candidate can not win. In the 2009 election the Republican candidate was not that far from beating the Democrat at the final round. They might hope for a change in the (poll) opinions and winning many enough votes to win. Note also that 495 of the Republican (Wright) supporters preferred the Progressive (Kiss) to the Democrat (Montroll), so the recommendation should be soft (or maybe they wouldn't care about that). Many people might also think that it is natural that the Democrat candidate does not win because of his "low first preference support". Just like people have become used to the flaws of Plurality, they might get used to the problems of IRV. I'm not sure for which ones of these three parties Plurality is strategically better than IRV.

1332: M>K>W
767: M>W>K
455: M
2043: K>M>W
371: K>W>M
568: K
1513: W>M>K
495: W>K>M
1289: W

Juho