Re: [EM] (3) MJ -- The easiest method to 'tolerate'
2016-09-21 18:59 GMT-04:00 Kristofer Munsterhjelm km_elmet@t-online.de:
On 09/06/2016 01:29 AM, Jameson Quinn wrote:
...
If that's true, then there's some kind of threshold of number of
grades,
below which there aren't enough grades for the ballot format to
encourage grading against a common standard. So three-slot methods
would
have to be tested to see if voters would vote grading-style or
relative-rank style with three grades, or if three grades are still
too few.
Personally, I'd guess that three would be enough. I think the four most
common voting heuristics, in descending order, would be:
First, as I've said: approve of one, disqualify greater evil among the
frontrunners and any evils greater still.
Second: Approve of one, disqualify both frontrunners.
Third: if one side of the left-right divide got used to habitually
losing, the centrists among them might begin to extend approval all the
way to the most-centrist on the other side.
Fourth: Approve of one, disqualify unqualified/unserious candidates.
Any of the heuristics above would tend to lead to a "successful"
resolution of the Chicken Dilemma.
That's kind of going into the domain of "manual DSV", though, which I'm
not as much a fan of. MJ has this going for it that there are ways for
honest voters to vote as long as the categories are well-defined.
Approval is a lot muddier, because it's much less certain that honest
voters can divide the candidates into "I like these" and "I definitely
don't like these". Three-slot methods could work if the heuristics are
common and intuitive enough, but they're kind of in-between MJ's
expressiveness and having Approval's manual DSV needs.
Median-based methods, especially those which break ties using above-median
votes, can do well with chicken dilemma scenarios. The flipside of this is
that in order to handle center-squeeze scenarios, they require the voters
who favor the centrist CW to put all other candidates below the winning
median; for safety, at bottom-rating.
I think that's somewhat plausible as a naive strategy ("Since I'm Center, I
think Left and Right are equally bad, so even though I don't hate them as
much as they hate each other, I might as well put both of them at bottom
rank"). I also think that when Center voters don't so strategize, the
outcome is not too bad; generally, that will tend to be in cases where
Center might even have lost a score election, and the candidate who beats
Center might even be the utility winner or at least close to it.
But yes, there is this much "manual" strategy necessary, and I don't see
any way around it. I think a system can't be robust to strategy in both
Chicken and Center Squeeze scenarios, and I'd rather get Chicken right in
spite of some strategy (and thus not encourage strategies which, when
over-applied, can end up electing the CL) instead of getting Center Squeeze
right without any strategy.
What's a good scenario to use to illustrate IIA failure in ranked
Bucklin? Seems to me any such scenario would be solved by a simple
truncation from the non-cloning side, which seems strategically obvious
enough.
Perhaps a crowding or "innocent cloning" example would work. E.g.
something like:
n candidates are in the running, representing various positions in issue
space. Someone in the top area of the issue space decides to withdraw,
and the winner flips from left to right.
I haven't checked if Bucklin is vulnerable to crowding, however, but in
the worst case, you could use a Condorcet 3-cycle example where removing
A changes the winner from B to C. IIA is a lot stronger than
independence to clones, after all.
Such scenarios depend on the tiebreaker, but I think it should be easy to
build one for most concrete tiebreakers.
On 09/22/2016 03:38 AM, Jameson Quinn wrote:
2016-09-21 18:59 GMT-04:00 Kristofer Munsterhjelm <km_elmet@t-online.de
mailto:km_elmet@t-online.de>:
On 09/06/2016 01:29 AM, Jameson Quinn wrote:
...
If that's true, then there's some kind of threshold of number of grades,
below which there aren't enough grades for the ballot format to
encourage grading against a common standard. So three-slot methods would
have to be tested to see if voters would vote grading-style or
relative-rank style with three grades, or if three grades are still
too few.
Personally, I'd guess that three would be enough. I think the four most
common voting heuristics, in descending order, would be:
First, as I've said: approve of one, disqualify greater evil among the
frontrunners and any evils greater still.
Second: Approve of one, disqualify both frontrunners.
Third: if one side of the left-right divide got used to habitually
losing, the centrists among them might begin to extend approval all the
way to the most-centrist on the other side.
Fourth: Approve of one, disqualify unqualified/unserious candidates.
Any of the heuristics above would tend to lead to a "successful"
resolution of the Chicken Dilemma.
That's kind of going into the domain of "manual DSV", though, which I'm
not as much a fan of. MJ has this going for it that there are ways for
honest voters to vote as long as the categories are well-defined.
Approval is a *lot* muddier, because it's much less certain that honest
voters can divide the candidates into "I like these" and "I definitely
don't like these". Three-slot methods could work if the heuristics are
common and intuitive enough, but they're kind of in-between MJ's
expressiveness and having Approval's manual DSV needs.
Median-based methods, especially those which break ties using
above-median votes, can do well with chicken dilemma scenarios. The
flipside of this is that in order to handle center-squeeze scenarios,
they require the voters who favor the centrist CW to put all other
candidates below the winning median; for safety, at bottom-rating.
I think that's somewhat plausible as a naive strategy ("Since I'm
Center, I think Left and Right are equally bad, so even though I don't
hate them as much as they hate each other, I might as well put both of
them at bottom rank"). I also think that when Center voters don't so
strategize, the outcome is not too bad; generally, that will tend to be
in cases where Center might even have lost a score election, and the
candidate who beats Center might even be the utility winner or at least
close to it.
But yes, there is this much "manual" strategy necessary, and I don't see
any way around it. I think a system can't be robust to strategy in both
Chicken and Center Squeeze scenarios, and I'd rather get Chicken right
in spite of some strategy (and thus not encourage strategies which, when
over-applied, can end up electing the CL) instead of getting Center
Squeeze right without any strategy.
Do you think there's a way to formalize vulnerability to center squeeze?
I imagine there would be two criteria:
- No center squeeze outright (e.g. IRV)
- No center squeeze with strategy
And I suppose for the latter, you could make a rather heavyhanded
criterion saying something like: if C is center and strategy can make
not-C win but not make C win, then it's vulnerable to strategic center
squeeze...
but that doesn't feel very elegant. Any ideas? Perhaps something
involving votes being drawn from a spatial model so that the idea of
"center" is relatively apparent?
The point is that if we had a formal model, I could check what methods
pass the criterion (or often pass it), and then see if there's anything
that both passes CD and whatever it ends up being.
Do you think hybrids that use both Condorcet and positional data (like
my fpA-fpC stub method or Benham/Woodall methods) pass both CD and
center squeeze? They do at least elect the centrist when there is a CW.
I guess the question would be how badly they degrade when there is no CW.
Could someone add a writeup of Majority Judgement to the wiki?
http://wiki.electorama.com/wiki/Category:Single-winner_voting_systems
On Thu, Sep 22, 2016 at 5:23 AM, Kristofer Munsterhjelm <
km_elmet@t-online.de> wrote:
On 09/22/2016 03:38 AM, Jameson Quinn wrote:
2016-09-21 18:59 GMT-04:00 Kristofer Munsterhjelm <km_elmet@t-online.de
mailto:km_elmet@t-online.de>:
On 09/06/2016 01:29 AM, Jameson Quinn wrote:
...
If that's true, then there's some kind of threshold of number
of grades,
below which there aren't enough grades for the ballot format to
encourage grading against a common standard. So three-slot
methods would
have to be tested to see if voters would vote grading-style or
relative-rank style with three grades, or if three grades are
still
too few.
Personally, I'd guess that three would be enough. I think the four
most
common voting heuristics, in descending order, would be:
First, as I've said: approve of one, disqualify greater evil among
the
frontrunners and any evils greater still.
Second: Approve of one, disqualify both frontrunners.
Third: if one side of the left-right divide got used to habitually
losing, the centrists among them might begin to extend approval
all the
way to the most-centrist on the other side.
Fourth: Approve of one, disqualify unqualified/unserious
candidates.
Any of the heuristics above would tend to lead to a "successful"
resolution of the Chicken Dilemma.
That's kind of going into the domain of "manual DSV", though, which
I'm
not as much a fan of. MJ has this going for it that there are ways
for
honest voters to vote as long as the categories are well-defined.
Approval is a *lot* muddier, because it's much less certain that
honest
voters can divide the candidates into "I like these" and "I
definitely
don't like these". Three-slot methods could work if the heuristics
are
common and intuitive enough, but they're kind of in-between MJ's
expressiveness and having Approval's manual DSV needs.
Median-based methods, especially those which break ties using
above-median votes, can do well with chicken dilemma scenarios. The
flipside of this is that in order to handle center-squeeze scenarios,
they require the voters who favor the centrist CW to put all other
candidates below the winning median; for safety, at bottom-rating.
I think that's somewhat plausible as a naive strategy ("Since I'm
Center, I think Left and Right are equally bad, so even though I don't
hate them as much as they hate each other, I might as well put both of
them at bottom rank"). I also think that when Center voters don't so
strategize, the outcome is not too bad; generally, that will tend to be
in cases where Center might even have lost a score election, and the
candidate who beats Center might even be the utility winner or at least
close to it.
But yes, there is this much "manual" strategy necessary, and I don't see
any way around it. I think a system can't be robust to strategy in both
Chicken and Center Squeeze scenarios, and I'd rather get Chicken right
in spite of some strategy (and thus not encourage strategies which, when
over-applied, can end up electing the CL) instead of getting Center
Squeeze right without any strategy.
Do you think there's a way to formalize vulnerability to center squeeze?
I imagine there would be two criteria:
- No center squeeze outright (e.g. IRV)
- No center squeeze with strategy
And I suppose for the latter, you could make a rather heavyhanded
criterion saying something like: if C is center and strategy can make
not-C win but not make C win, then it's vulnerable to strategic center
squeeze...
but that doesn't feel very elegant. Any ideas? Perhaps something
involving votes being drawn from a spatial model so that the idea of
"center" is relatively apparent?
The point is that if we had a formal model, I could check what methods
pass the criterion (or often pass it), and then see if there's anything
that both passes CD and whatever it ends up being.
Do you think hybrids that use both Condorcet and positional data (like
my fpA-fpC stub method or Benham/Woodall methods) pass both CD and
center squeeze? They do at least elect the centrist when there is a CW.
I guess the question would be how badly they degrade when there is no CW.
Election-Methods mailing list - see http://electorama.com/em for list info
Could someone add a writeup of Majority Judgement to the wiki?
http://wiki.electorama.com/wiki/Category:Single-winner_voting_systems
On Thu, Sep 22, 2016 at 5:23 AM, Kristofer Munsterhjelm <
km_elmet@t-online.de> wrote:
On 09/22/2016 03:38 AM, Jameson Quinn wrote:
2016-09-21 18:59 GMT-04:00 Kristofer Munsterhjelm <km_elmet@t-online.de
mailto:km_elmet@t-online.de>:
On 09/06/2016 01:29 AM, Jameson Quinn wrote:
...
If that's true, then there's some kind of threshold of number
of grades,
below which there aren't enough grades for the ballot format to
encourage grading against a common standard. So three-slot
methods would
have to be tested to see if voters would vote grading-style or
relative-rank style with three grades, or if three grades are
still
too few.
Personally, I'd guess that three would be enough. I think the four
most
common voting heuristics, in descending order, would be:
First, as I've said: approve of one, disqualify greater evil among
the
frontrunners and any evils greater still.
Second: Approve of one, disqualify both frontrunners.
Third: if one side of the left-right divide got used to habitually
losing, the centrists among them might begin to extend approval
all the
way to the most-centrist on the other side.
Fourth: Approve of one, disqualify unqualified/unserious
candidates.
Any of the heuristics above would tend to lead to a "successful"
resolution of the Chicken Dilemma.
That's kind of going into the domain of "manual DSV", though, which
I'm
not as much a fan of. MJ has this going for it that there are ways
for
honest voters to vote as long as the categories are well-defined.
Approval is a *lot* muddier, because it's much less certain that
honest
voters can divide the candidates into "I like these" and "I
definitely
don't like these". Three-slot methods could work if the heuristics
are
common and intuitive enough, but they're kind of in-between MJ's
expressiveness and having Approval's manual DSV needs.
Median-based methods, especially those which break ties using
above-median votes, can do well with chicken dilemma scenarios. The
flipside of this is that in order to handle center-squeeze scenarios,
they require the voters who favor the centrist CW to put all other
candidates below the winning median; for safety, at bottom-rating.
I think that's somewhat plausible as a naive strategy ("Since I'm
Center, I think Left and Right are equally bad, so even though I don't
hate them as much as they hate each other, I might as well put both of
them at bottom rank"). I also think that when Center voters don't so
strategize, the outcome is not too bad; generally, that will tend to be
in cases where Center might even have lost a score election, and the
candidate who beats Center might even be the utility winner or at least
close to it.
But yes, there is this much "manual" strategy necessary, and I don't see
any way around it. I think a system can't be robust to strategy in both
Chicken and Center Squeeze scenarios, and I'd rather get Chicken right
in spite of some strategy (and thus not encourage strategies which, when
over-applied, can end up electing the CL) instead of getting Center
Squeeze right without any strategy.
Do you think there's a way to formalize vulnerability to center squeeze?
I imagine there would be two criteria:
- No center squeeze outright (e.g. IRV)
- No center squeeze with strategy
And I suppose for the latter, you could make a rather heavyhanded
criterion saying something like: if C is center and strategy can make
not-C win but not make C win, then it's vulnerable to strategic center
squeeze...
but that doesn't feel very elegant. Any ideas? Perhaps something
involving votes being drawn from a spatial model so that the idea of
"center" is relatively apparent?
The point is that if we had a formal model, I could check what methods
pass the criterion (or often pass it), and then see if there's anything
that both passes CD and whatever it ends up being.
Do you think hybrids that use both Condorcet and positional data (like
my fpA-fpC stub method or Benham/Woodall methods) pass both CD and
center squeeze? They do at least elect the centrist when there is a CW.
I guess the question would be how badly they degrade when there is no CW.
Election-Methods mailing list - see http://electorama.com/em for list info