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

[Michael Ossipoff]

On Sat, Sep 22, 2012 at 6:11 PM, Juho Laatu <juho4880 at yahoo.co.uk> wrote:
> 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.

You're the one who wants to use the notion of "the best winner with
sincere votes". Odd that you need to ask me to describe your ideal
sincere winner. If you want to object that ICT and SITC don't choose
the ideal sincere winnner well enough, then you're the one who needs
to say what you mean by "the best winner with sincere votes".

But, with all sincere ballots, many like the idea of electing the CW:
The candidate who pair-beats each of the others, when such a candidate
exists. When "CW" is legitimately defined, when equal top and equal
bottom ranking are interpreted consistent with the preferences, intent
and wishes of people voting in that way, then SITC elects the CW.
Beatpath, VoteFair, and all unimproved Condorcet methods fail to elect
the legitimately-defined CW.

So, there is a popular "ideal sincere winner": the CW.

You said:

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.

[endquote]

A sincere-voting property of SITC is that it elects the
legitimately-defined CW. It's the method that does that.

You see, what you're missing is that the same disregard for voters
preference, wishes and intent tha makes unimproved Condorcet fail FBC,
also makes it fail the legitmately-defined Condorcet Criterion, and
fail to elect the legimately-defined CW.

So, meeting FBC doesn't require some sort of violation of the choice
of ideal sincere winner. On the contrary, it comes with the election
of the ideal sincere winner, because both gains come from respecting
the voters' intent and preference.

You said:

My understanding is that they have been designed to resist certain
strategies, not only to pick the best winner with sincere votes.

[endquote]

As explained above, Symmetrical ICT avoids favorite-burial need
precisely _because_ it respects voter wishes. And if the CW and the
Condorcet Criterion are defined according to voter wishes, then
Symmetrical ICT is the method that elects the CW when there is one,
and meets the Condorcet Criterion.

You said:

Therefore there must be another method that elects the best winner
(based on the definition that you gave) more often than they do.

[endquote]

So that's your best argument: That, because SITC meets FBC, there must
be a method (unspecified by you) that does better under sincere
voting.

The reason why you don't specify a method that does better than SITC
under sincere voting is because you don't even know what a method
should do under sincere voting. You ask me to describe the ideal
sincere winner, because you don't have any idea what the ideal sincere
winner should be.

But I gave you a suggestion: The legimately-defined CW.

Do you see the irony here? Someone who doesn't know what the ideal
sincere winner is, wants say that surely there's some method that
chooses it better than Symmetrical ICT. He just doesn't know what that
method is, because he doesn't have a suggestion for what the ideal
sincere winner would be.

>>>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.

Translation: You can't name one.

You said:

> (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).)

[endquote]

That sounds like Dodgson. Sure, it can be justified as you say.

You want to elect the best winner under sincere voting. Is that what
you claim is the best winner under sincere voting (ideal sincere
winner)?

You described a circular tie solution, for when there's no CW. And
presumably the CW that you'd choose would be the traditional (as
opposed to legitimate) one.

So, for one thing, your method wouldn't choose the candidate who
legitimately beats each one of the others under sincere voting.

And, if you say that SITC's justification doesn't apply in sincere
voting, then you'd be mistaken.

Say you like X and Y equally, and you rank them both in 1st place.The
fact that you like them equally and rank them sincerely in 1st place
doesn't mean that you want one to beat the other and give the election
to your last choice. SITC respects your wishes better than unimproved
Condorcet, even if your equal top ranking is sincere.

For another thing, everyone agrees that the election of the CW under
sincere voting is a lot more important than how you choose when there
_is_ no CW. So the circular-tie-breaker isn't so important.

For yet another thing, natural circular ties are considered to be
uncommon. Certainly they'd be rare, to the extent that the scenario
approximates a 1-dimensional political spectrum, in which issues are
strongly correlated (as they tend to actually be).

>>> ...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.

Does any method? You don't know, because you don't know what an ideal
sincere winner would be.

Aside from that, I answered that statement above.SITC elects the ideal
winner better than unimproved Condorcet does, because it better
respects voters' intent and preference.

When no candidate beats everyone, SITC elects from the set of unbeaten
candidates. When no one is beaten, SITC doesn't necessarily choose
from the Smith set--probably not even from a legitimately-defined
Smith set. Choosing from the Smith set would lose one or more of
SITC's desirable properties. But I remind you that the time when it
matters who wins under sincere voting is when there is an unbeaten
candidate. Or more than one unbeaten candidate. When there's no CW,
it's anyone's guess who should win, even under sincere voting.

Dodgson's choice is one of many opinions about who should win under
sincere voting when there's no CW.

>> 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.

Ok, let's define the ideal sincere winner as the legitimately-defined
CW. Symmetrical ICT is the method that chooses the
legitimately-defined CW. Unimproved Condorcet doesn't.

>>> 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,...)

And remember that unimproved Condorcet also has the chicken dilemma.
You said that you don't think that people would favorite-bury. I've
answered that amply, but do you also believe that there will be no
chicken dilemma? Because, if the chicken dilemma will happen, then it
will happen in unimproved Condorcet, because unimproved Condorcet has
the chicken dilemma. SITC doesn't have the chicken dilemma.

Your talk of sincere voting loses even what relevance it had before,
when I remind you that unimproved Condorcet has the chicken dilemma.

>> ...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.

That's nice. I don't propose Approval, Score and SITC for "many
societies". I propose them for the U.S.  (Approval and (maybe) Score
for official public elections; and SITC for informational polling--but
Score for informational polling when there isn't agreement about
choice of rank-count).

You said:

I start from that assumption and I want evidence before deviating from
that assumption.

[endquote]

Unsupported assumptions tend to lead to error.

If you choose some (unspecified) method that doesn't offer good
strategy-guarantees, and it turns out that your strategy-free public
is a mistaken assumption, then you've made a mistake.

SITC doesn't depend on an all-voters-sincere assumption. It would work
fine with or without strategically-inclined voters. It would work fine
with or without everyone completely non-strategic.

And remember, I asked if you think that the chicken dilemma, too,
won't happen.  ...In other words, I ask if you think that there
wouldn't be defection in the familiar chicken dilemma example, in the
U.S. in particular, or in "most societies".

You depend on an assumption. You think that maybe your assumption is
right. Sometimes "maybe" isn't good enough. You don't claim that there
wouldn't be favorite-burial in the U.S. You say you've had
conversations with Americans. Does it occur to you that there could be
some "sample bias" there? How often does Joe Sixpack really get to
Europe?

Do you also assume no chicken dilemma?

SITC doesn't need an assumption of sincere voting. Nor does it fail to
choose well when everyone votes sincerely.

All the fighting about which unimproved Condorcet version is best is
quibbling about what is best when there is no CW. ...in other words,
about the least important circumstance, the time when there is a
natural (sincere) circular-tie. Aside from that, as I said, natural
circular ties are considered uncommon.

You said:

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.

[endquote]

I guess I must have missed the part about digitization. Anyway, though
the ballots should, of course, be saved, they should also be _tallied_
right there in public, in front of the multiparty observers. That's
what I suggest for Approval counts.

You can't do that for a rank method. You can do it for Approval.

>
>> 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,

...only if the machine is printing what the voter says :-)

You continued:
but in practice not quite at the same level.

[endquote]

No, not quite :-)


>
>> 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.

Juho, our local precincts are all around the country.

You continued:

And maybe better so (to store them under the eyes of all the locals
who don't want their opinions to be falsified).

[endquote]

Not wanting their opinions falsified, and not getting their opinions
falsified, aren't quite the same thing.

Security can't be perfect.

Best to do the actual tally of the candidates totals during the public
count process. You still save and store the ballots, but you don't
depend on them for count verifiability.

That tally during the public count procedure pretty much disqualifies
all rank methods, and anything other than Approval or Plurality. Maybe
Score.


>
>> 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. Only if the end product of the digitization is really what the voter wrote on hir ballot.

You said:

A different procedure applies for the ballot digitization.

[endquote]

Yes, that's the problem, isn't it.

>
>> 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.

What are these other threats that you refer to? Let me guess: You
don't know, and you were going to ask me :-)

I've compared Symmetrical ICT to unimproved Condorcet, by a number of
criteria, including Condorcet's Criterion. I've compared them in
regards to electing the legitimately-defined CW.

You said:

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.

[endquote]

With you, of course, deciding how much protection is practical. Such
hoping isn't needed when a method outright doesn't have the problem.

You want to imply that, though SITC doesn't have a favorite-burial
problem, or a chicken dilemma, or a Later-No-Help failure, and elects
the legitimately-defined CW (unlike unimproved Condorcet), there is
some other need that it doesn't meet, or some other threat that it
doesn't protect against, or some other necessary guarantee that it
doesn't offer.. But you can't tell us what it is. Your best argument
is that there _might_ be one :-)

>
>>> 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 :-).

...And it's only a question of how many "some" is. You don't know. You
speculate that it won't be many, "in most societies" or "in many
societies". I'm more concerned about this particular society, in this
country. You admit that you don't know about that, and there's no
reason for anyone to say that you should know about that. You clarify
that you're only speaking in general, about "most societies" or "many
societies". Fine.

But as for _random_ strategic votes, they aren't really random.
They're predictable and systematic. They're heavily recommended by the
mass media. You seem to be missing that.

And the favorite-burials are indeed irrational, in the sense that the
premise for choosing them is irrational. But, given that premise, the
favorite-burial is quite rational, optimal strategy.


>
>>> 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.

Translation: You can't name a way that SITC would do harm, and can't
name a method that would do better.

>> "Next time, don't let that happen. Next time, rank the Democrat in 1st
>> place, because otherwise the Progressive will win again."

You replied:

> 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.

[...]

Fine. For national elections, the mass media continually, daily,
hammer home the message that the Dems and Repubs are "the two
choices".  ...the message that no one can win other than the Dems and
Repubs. With great success, in fact, the media often imply that there
_are_ no other parties, and that there are no non-disastrous
positions, no positions that should even be considered or heard, other
than the Dem and Repub policies.

So yes, the media do indeed "make such a recommendation." They make it
every day, on every channel and station, and everyone accepts it.

It would be nice to educate everyone differently. I don't think the
mass media want to.

But there are voting systems that, even to someone who believes the
media (which is most everyone), there would be no reason to do
favorite-burial.

Approval, Score, and Symmetrical ICT are a few of those methods.

You speak of "most societies". Maybe "most societies" aren't
(voluntarily) a captive audience of our mass media.

Mike Ossipoff