At 09:58 PM 12/15/2008, Kevin Venzke wrote:
Kevin's post had lost all formatting, the quoted
material was extremely difficult to follow, and
the new text was only distinguishable with
difficulty, because I recognize, sort of, my own
writing. So I may have missed a lot....
Hi, --- En date de : Dim 14.12.08, Abd
ul-Rahman Lomax <[email protected]> a écrit :
Remember, not all voters will
follow >frontrunner strategy. They don't with
Plurality, why should they start with Approval?
Well, I'm not using "frontrunner strategy" but
"better than expectation" strategy, since that can be applied more universally.
"Frontrunner strategy" is a common one that seems
to help with ranked methods as well as Range
ones. Make sure you cast a maximally effective
vote for a frontrunner, and, where "against"
matters, against the worst one. Usually there are
only two frontrunners, so it's easy.
"Expectation" is actually tricky if one doesn't
have knowledge of the electorate's general
response to the present election situation. How
do you determine "expectation." Mean utility of
the candidates is totally naive and non-optimal.
It's not how I'd vote, but, then again, I
strongly want to see majority requirements, which
makes bullet voting much safer.
But it's a complex issue. My point is that
"better than expectation" has been taken to mean
"average of the candidates," which is poor
strategy, any wonder that it comes up with mediocre results?
If D voters are more resilient then it's
possible that B will sink instead. It's not as
likely to be C, though, since C has an avenue
of bouncing back that B and D lack. In this
simulation, I don't simulate voters who don't
care if their vote isn't expected to be effective.
Sure. To my knowledge, nobody has. But if you
generate random utilities, then, you are missing
something: voters with below a certain level of
preference strength won't put any effort into
voting. They won't show up for a special election
like a runoff or a primary that isn't scheduled
with the general election. Some of them will
bullet vote, if they have a distinguishable
preference, but it doesn't mean much, they won't
exercise themselves for strategy, since it is all
the same to them, more or less.
I have in mind, remember, Saari's preposterous
example, where 9,999 voters approve the middle
candidate ("mediocre") because this one is at or
above the average of their favorite and the
worst. And then comes one "nutty voter" who votes
reversed preference, and Mr. Mediocre wins. Of
course, what if the "nutty voter" hadn't come
along? Mr. Mediocre might still have won, if
there was a tiebreaker method. Totally silly
example. People just won't vote that way.
The hard part is encouraging people to add
additional Approvals, if they prefer a
frontrunner, or just if they have a significant
preference for one. And it's not clear that we
should even try! Not in a first round, anyway.
Bucklin is nice because it puts up a small fence,
to protect a first preference, but not to prevent
compromise in the second round, etc. In Bucklin,
do you think that a majority of voters would add
a mediocre second choice as an additional
approval in the first round? Hardly! So *theory*
might show Bucklin as not satisfying the Majority
Criterion if we allow additional approvals in the
first rank, but that's totally unrealistic in
public elections. People will bullet vote, lots
of them. FairVote claims almost 90% did in
Bucklin elections used for political primaries in
the U.S (What they don't say is that IRV likewise showed heavy truncation.)
The facility of additional votes helps supporters
of minor candidates, it gives them a choice that
they didn't have under Plurality. But most voters
don't need it and most won't use it. Fixing the
spoiler effect, generally, takes only a few
percent of voters using additional ranks or
approvals. (This is entirely separate from the
illusory help provided by IRV, in fabricating a
majority by discarding exhausted ballots.)
To summarize this, the scenario makes sense
only if B, C, and D are in a near-tie. If both
B voters and D voters prefer C over the other
of B and D, then C is, indeed, their compromise
candidate! It's perfectly rational that the B
and D voters, iterating over polls, increase
their support for C, but it will never go all the way.
Well it wouldn't be both the B and D factions.
You would only add votes for C if you believe
your expectation is dropping. That happens when
your preferred candidate (D) looks to be
slipping. The B voters have no need to
compromise that far. In this situation, D
voters who decline to vote in the main contest
are basically "voting for Nader."
That's right, and it is their right, and that
many voters do this prevents the "mediocre
candidate" scenario from happening. And if a
majority is required, it's all safer. Want to
vote for Nader alone in the primary? Fine. If
enough people do that, there will be majority
failure and there will be a runoff. Slightly
improved chance that Nader is in that runoff!
I.e., the polls or whatever other expectations
existed were wrong. He wasn't a "minor
candidate," he was a frontrunner, in fact.
Approval and similar methods simply allow voters
to make a *reasonably safe* move toward some
compromise. IRV "protects" them from helping an
opponent of their favorite, but, at the same
time, protects other candidates such that the
favorite might be prevented from winning. IRV
proponents emphasize the protection, but
certainly not the loss of opportunity. In
reality, the question doesn't arise for most
voters. Would Nader voters have been worried, in
2000, that their vote for a frontrunner, say
Gore, might have "helped Gore to beat Nader"? I don't think so.
As to those who prefer a frontrunner, they are
highly unlikely to add an additional Approval for
another frontrunner. Voting for Gore *and* Bush? What? Why bother?
> The behavior described seems reasonable,
proper, and is > effective for finding a
compromise winner. Is there some > problem with it?
No, I don't think so. It's pretty good behavior
actually. At least on its face, it would seem
that Approval would ruthlessly favor the median
voter's candidate in this kind of scenario.
Well, probably. That's the most likely candidate
to be the best compromise, to attain a majority.
(If plurality Approval is adequate, all methods are more dangerous!)
The big concern is what happens when poll stability can't be achieved.
Nah! Most voters won't pay that much attention to
polls, they will just vote their gut. Polls will
be used by those who are very seriously involved,
who want to maximize the power of their vote. I
think most of the "big concern" is simply
imagination. There won't be big surprises with Approval. Little ones, sure.
A poll would have to be *way* off to seriously
impact my Approval Vote in a majority-required
system. In plurality Approval, strategy based on
polls would loom larger. Sure, it could
oscillate. But how large would the osciallations
be? And, in the end, the winner is the candidate
accepted by the most voters. It's not going to be
a terrible result, if Approval falls flat on its
face, it elects a mediocre candidate because the
voters didn't get the strategy right.
But working against this is the natural tendency
to bullet vote, which should prevent that
outcome.... and which might increase the need for
a runoff, but a runoff between, say, top two
approved candidates, should fix the "mediocre"
problem. (I prefer, you know, using a full Range
ballot and preference analysis, to detect
Condorcet failure and provide a means for the
majority (or at least a plurality!) to fix it.
Bucklin allows them to maintain their sincere
preference, but, effectively, vote this way.
Some might add C in the second rank, some in
the third, depending on their preference
strength. But some will always bullet vote,
perhaps even most. Real voters don't give up so easily as your simulated ones!
I did simulate MCA, and yes, the D voters
continued to vote for D as their favorite (they
were not allowed to list multiple favorites, but
this was simply to make the coding more
manageable). I don't know what you mean by
voters not giving up so easily as my simulated
ones. How easy is easy? I could conceivably
program some voters to insist on being sincere.
(In whatever sense that it is not sincere to
vote also for C.) But it seems to me that this
type of voter is a bad thing for Approval, just
as it is under Plurality. Kevin
Venzke ---- Election-Methods mailing list
- see http://electorama.com/em for list info
What type of voter is bad for Approval? Easy compromiser or tough bullet voter?
(Multiple favorites isn't terribly important in
Bucklin, but it's a way of handling overvotes:
interpret them! And if there are two candidates
and I have trouble deciding which I prefer, they
are both "favorite," allowing equal ranking makes
the voter easier -- and more accurate as well,
more true to actual preferences.)
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