Right; that's largely my concern. It's also why I'm concerned about
blasting emails to the EM list saying stuff like "RANKED PAIRS HAS A 50%
MANIPULATION RATE, AND IRV HAS A 7% RATE", given this list includes lots of
people who are less involved in these discussions and don't know
manipulability is a very narrowly-defined measure of strategy-resistance.

A good example of this is James Green-Armytage's papers or Tideman's book
on this topic. I constantly have to deal with people who think his
studies show IRV is "93% STRATEGYPROOF" and every other method "collapses"
under strategic voting. (When systems like score, approval, etc. react
quite well to strategy, because they behave like maximal lotteries.)

Manipulation rate is like a p-value. It's a somewhat-meaningful metric that
can be useful when handled delicately by an expert. The issue is it
sounds *very
*similar to a different, much more important, question like "how well will
this method react to strategic voting". It's not that important to know
whether it's theoretically possible, given perfect information and
coordination, to manipulate the election; much more interesting are
questions like "what happens at the strategic equilibria" and "how robust
are those equilibria when we fiddle with the assumptions".

I'm also kinda interested in behavior with different kinds of strategy. I
think voters are about equal-parts expressive, level-strategic (they care
about how high the candidates' scores are, e.g. people who turned out in
France 2003 because they wanted to show France had "rejected" Le Pen), and
winner-strategic.

On Tue, May 14, 2024 at 8:59 AM Kristofer Munsterhjelm km_elmet@t-online.de
wrote:

On Tue, May 14, 2024 at 08:58 Kristofer Munsterhjelm km_elmet@t-online.de
wrote:

[…]

And another part of

Yes, then, as you suggest, “manipulability” doesn’t tell us anything of
interest. I agree.

Then how much do those manipulability numbers mean, in regards to the
strategic merit of the methods. Nothing?

If “manipulation” consists of getting, by voting insincerely, an outcome
better than what a sincere ballot would get, then what do you mean by a
sincere ballot in Approval?

If there are more than 2 candidates, then, for a particular voter, there
might not even be a strongly-sincere ballot.

Then a weakly-sincere one? Every ballot that isn’t obviously suboptimal is
weakly-sincere. There are lots of weakly-sincere ways to make-out an
Approval-ballot.

So then, what does it mean to say that a voter in Approval has
“manipulated”?

Yes, the Above-The-Mean strategy is regarded as the only sincere strategy
in spatial-simulations. Is that accurate? Of course not.

Above-Mean is one strategy that you can use. It’s one among many. …& it’s
incorrect to say that any other way of voting is insincere. As I said, any
strategy not obviously suboptimal is weakly-sincere.

So spatial simulations plainly aren’t saying anything valid about Approval.

Does that bother the academics? Nah :-)

Our elections have unacceptable candidates. Acceptability & unacceptably
are evident without polls.

Approve (only) all of the Acceptables.

But yes, of course, if someone believes that there are no unacceptable
candidates, then some (certainly not all) ways of choosing how to vote can
use poll information. e.g. the Best-Frontrunner strategy (…& no, the
Democrat & the Republican aren’t the frontrunners).

Better-Than-Expectation, too, is affected by predictive information.

Voting for the Acceptables, or ( if everyone is acceptable), for everyone
you like, or ( if you like or dislike them all), for those above the
biggest merit-gap, or above the mean, lor (if you don’t have an estimate
for the mean),voting for the best half of the candidates… etc.:  Those ways
of choosing how to vote don’t need polls.

About Beatpath, MinMax & Ranked-Pairs: Did you use wv or margins?

In roughly 1/3 of the elections, those methods were reported as having
someone gain from insincerity. That’s surprising if wv was used.

but wouldn't care in a Baldwin's

…because manipulability, by itself doesn’t measure strategic merit.

I’ve suggested judging a method’s merit by the drastic-ness of the
defensive strategy that it can make necessary.

A simulation could compare the methods by how often that need occurs.

For Condorcet-versions, it would be enough to determine ratio of backfire
to success, for offensive-strategy.

Academic authors have latched onto “manipulability”. That doesn’t make it
a useful measure.

…&, when simulations report how often strategy in Condorcet succeeds in
improving the strategists’ outcome, they don’t compare that to how often it
would worsen their outcome.

The simulations don’t capture deterrence, something all-important to
Condorcet strategy.

On Wed, May 15, 2024 at 01:46 Michael Ossipoff email9648742@gmail.com
wrote:

śr., 15 maj 2024, 10:47 użytkownik Michael Ossipoff email9648742@gmail.com
napisał:

I can't agree at all. IMO the primary goal of a good voting method is to
make voters not regret voting honestly. While it's useful to be able to use
a defensive strategy after analysing expected poll outcomes, frontrunners
etc., the best voting method would be the one that does not create the need
to take these things into the account at all.
Chances of being able to vote honestly, with no strategic burden to bear.
That's what the manipulability numbers are about.

("at all" meaning "as often as possible", of course)

śr., 15 maj 2024, 17:04 użytkownik Filip Ejlak tersander@gmail.com
napisał:

wt., 14 maj 2024, 17:59 użytkownik Kristofer Munsterhjelm <
km_elmet@t-online.de> napisał:

Well, applying an electoral method to an election space (let's ignore
cycles for a moment and assume that it's a space with an honest CW in every
case) divides this space into unmanipulable elections (with resistant CWs)
and manipulable elections (with vulnerable CWs). In the manipulable space,
these manipulability stats don't care about whether we choose the honest CW
or not.
I guess the situation is that Benham and IRV create more or less the same
electoral space division, but don't agree about winners in the manipulable
subspace (meaning choosing / not choosing CWs - which doesn't create a
difference in stats).

On 2024-05-15 10:46, Michael Ossipoff wrote:

It tells you how often you have to be thinking about "playing the
strategy game" to improve the outcome (or how often you may regret if
you don't). In a low manipulability method, you don't have to start
thinking about whether you should tailor your response to poll data,
etc. as much.

There are two approaches here: you can make an apparently simple but
highly manipulable method and then place the burden of voting "the right
way" on the voters. Or you can take the spirit of the revelation
principle further (it can never go all the way) and place that
responsibility on the voting method itself.

IMHO, the more a voting method supports "just go there and submit your
vote", the better it is, all else equal. As I have pointed out, it's not
the full picture - you also need to know that the sincere unmanipulable
outcome isn't going to suck. But that doesn't mean manipulability is
meaningless.

For a near-dichotomous opinion (A > B > C >>>>>> D > E > F), the answer
is easy. But for fully general opinions, you're absolutely right. You
have to make some assumption on honest behavior.

But it seems like the ambiguity is fundamental to Approval. The strategy
tester works by generating ballots for a sincere first stage and then
seeing if coalitions can change the winner. The defining feature of the
sincere stage is that nobody takes information about anybody else into
account (and that it adheres to the model, e.g. spatially distributed
utilities, impartial culture, whatnot).

So we need some way for the virtual zero info voters to transform
utilities to Approval ballots. The virtual voters have to answer Robert
Bristow-Johnson's question: "do I approve of my second favorite"? And
it's not at all clear how they should do it.

This reflects a property of Approval itself. The Approval ballot asks an
ambiguous question and it's up to the voter to interpret it.

Note that this ambiguity doesn't misclassify sincere ballots as
insincere ones. In the second (strategic) stage, any voter is allowed to
submit any ballot so long as it'll serve their purposes. What it does
affect is the weighting (how often would this particular first-stage
Approval election happen).

In practice, what the simulations do is use some kind of translation
function. Both JGA and I use a mean utility cutoff. It would of course
be possible to vary the "translation function" to see if the results are
robust.

It doesn't say that any other way of voting is insincere. It would just
consider the other ways of voting to happen too rarely or too often
given the spatial model.

Ultimately, we need a reasonable model of how sincere voters would vote
in the absence of poll data. Just like we need a reasonable utility
model to begin with (spatial vs IIA vs whatever). If the model is
unreasonable, then the results will be wrong. (Just like a wrong utility
model would produce wrong VSE or ranked method manipulability values.)

If it's impossible to create such a reasonable model because Approval
voting in non-u/a settings is too intervowen with the wider "adapt to
the polls" strategy, then there will be no meaningful results. But then,
that would be telling in itself.

Would running the simulations with different transformation functions
corresponding to the approaches you listed help, or would you still
consider the values to be meaningless?

I used full ranking, so wv vs margins makes no difference - though my
code is set to use wv.

That's not quite what I'm saying. Consider Random Ballot. It has zero
strategic merit because strategy will never help you: if you're the
fortunate voter whose first preference was picked, you can't do better
than getting your honest first preference. And if you're not that
fortunate voter, nothing you can do will make a difference.

So the strategy potential is zero, as would its manipulability be (with
"who is the lucky voter" held fixed between the honest and the strategic
round).

But its honest outcome, even in expectation, is really awful. If you add
a variance penalty, it gets worse still. Nobody proposes Random Ballot
as a single-winner method.

Manipulability rightly measures its strategic potential to be zero. But
we need more information: how good its honest outcome is. Same here.
That doesn't mean that manipulability is a useless strategy measure. It
just means it doesn't answer the other question we're interested in.

-km

On 2024-05-15 17:04, Filip Ejlak wrote:

Thank you for saying that much more succinctly than I did.

Although I would say that winner quality given honesty also matters :-)
At least to avoid the kind of outcomes that lead people to repeal the
method.

-km

Sure, Above-Mean is one of the main 0-info strategies. But so is
Above-Largest-Gap, which, in a simulation, could stand-in for u/a &
Like/Not-Like.

IRV is the prime embarrassment for the maipulability standard.

Yes, the goal of ranked methods is to avoid defensive-strategy need. IRV
has no offensive-strategy (to speak of), & is relatively unmanipulable, but
it has a really big need for drastic defensive-strategy, favorite-burial.

So I’m just saying that it would be better to report about the latter
instead.

We all agree that avoidance or reduction of defensive strategy need is the
goal of rank-methods. So, report that instead of
“manipulability”.

Comments inline:

On Wed, May 15, 2024 at 11:23 Kristofer Munsterhjelm km_elmet@t-online.de
wrote:

It doesn’t!!

IRV makes you play the strategy-game, & will make you regret that you
didn’t bury your favorite.

In a low manipulability method, you don't have to start

No, not poll-data, but the method’s own intrinsic wrongdoing.

Yes, & that’s another issue. I’ll comment about it below where you bring it
up.

IMHO, the more a voting method supports "just go there and submit your

It means that it would be better to just speak of & measure for what is
desired. No need to measure, report & speak of a fragment-component that
isn’t helpful by itself. Skip that & just report directly regarding the
desideratum itself.

Yes, many want the method to do everything for us. In fact I agree with RBJ
that, for an inimical electorate (like our public political elections), the
completely legalistic pairwise-count rank-methods (Condorcet) would be
best…all else being equal, as you said.

But all else is not equal !

Count-fraud is a problem. Condorcet’s humungously computation-intensive
count ridiculously facilitates count-fraud.

You want to do a handcount-audit of a Condorcet count?

Additionally, the count-program itself is easier to hide or add fraud-code
in.

As a general principle, then yes it’s much better to have the voters do it
for themselves rather than having a complicated fraud-prone
automatic-machine do everything for them.

A simple, reliable hand-tool is much better.

I’d much rather trust the voters to use the simple reliable hand-tool
(Approval) well, than trust everyone responsible for the count to not
perpetuate count-fraud.

I’m glad you brought up the desire for the method to do it all for
us…taking our sincere rankings as input, & outputting the legalistic right
choice. …because I’ve been meaning to address that matter.

…& that’s not even counting the much less expensive implementation (could
be zero cost, without even new count-software), easier less expensive
administration, & easier simpler explanation with consequent easier
enactment.

Approval isn’t as difficult to vote as it opponents claim.  There are many
ways to choose what or whom to approve. That’s a good thing, because you
can choose how you like.

Condorcet is legalistic, but we don’t have to be legalistic! Approval
guarantees election of the candidate who maximizes the number of voters for
whom the outcome is in their preferred of the two merit-subsets, however
the voter designates them.

e.g. If people approve what they like, Approval maximizes the number of
people who like the outcome.

If people approve what’s acceptable, then Approval maximizes the number of
people for whom the outcome is acceptable.

If people approve above expectation, then Approval maximizes the number of
people for whom the outcome is above expectation…maximizes the number of
people pleasantly surprised.

You don’t know the objectively-optimal vote? Neither does anyone else, so
don’t worry about it!

Probability, & therefore expectation & it’s optimization, depends on your
information.

Approving above your subjective perception of expectation genuinely
maximizes your expectation.

Ways of maximizing your expectation:

Approve everyone you’d appoint instead of holding the election. Or approve
everyone whose election wouldn’t disappoint you.

The polling CW is a good estimate of election-expectation. Approve hir &
everyone better.

If you perceive 2 likely frontrunners, approve the better one & everyone
better. (…but don’t believe the bullshit that the Democrat & the Republican
are the 2 choices).

If all were acceptable, I’d just approve whom I like. If I like them all,
I’d approve above mean, if I perceived the mean. But do we perceive the
mean? If not, maybe I’d approve the best half of them, or above the biggest
merit-gap.

Those are my comments. None farther down. Easier to say that than to delete
the rest of the text m.