Fwd: Fwd: U/P voting: new name for simple 3-level method.
2016-09-10 21:26 GMT-04:00 C.Benham cbenham@adam.com.au:
On 9/11/2016 5:02 AM, Kevin Venzke wrote:
43: A
24: B>C
23: C>B
10: D
Under MTA the B and C voters are being completely reasonable: They hope
for majority approval but can still hope for a win if they
don't get it.
Strategy is less likely to produce these ballots under U/P because the B
and C voters are taking a gamble. To get a similar outcome
they have to vote B=C. Anyone who doesn't is functionally defecting!
C: A very good example! Assuming MTA and MCA use Top Ratings scores to
break Approval ties, they both elect the Condorcet winner B.
But both could be shifted to C with a single C-only ballot, even if the B:C
ratio were 46:1 instead of 24:23.
U/P's under-use of the middle ratings slot means that it relies more on
its "majority disqualification" mechanism which seems to make it more
vulnerable to irrelevant ballots, as in the example.
Under U/P, without the irrelevant D ballots, A and D are disqualified and
B is the glorious winner. With them, B and C and D are disqualified and
(without needing
any others to be disqualified) A wins.
This causes me to reject U/P as clearly worse than MTA and MCA. Of the
three I (again) rate MTA as the least bad.
I think MTA is pretty darn good. I still prefer U/P.
I think that scenarios like the above are fundamentally pathological; any
possible winner has only minority approval, so that even assuming all
ballots are semi-honest, any of them could be a true Condorcet loser. Thus,
I believe that it's more important for a system to try to avoid scenarios
like the above, than to try to find a perfect winner in such a scenario. In
fact, in the related scenario:
43: A
40: B>C
6: C>B
1: C
10: D
... I think that a case can be made for either A or B. After all, they'd be
tied if we try to approximate Score by using truncatable Borda here. But no
serious case can be made for C or D, even though C wins MTA and MCA.
Anyway, I think U/P does a better job trying to discourage the kind of
strategy that would lead to a scenario like the above. And part of that is
the default rule which Chris has criticized.
One possible alternative default rule: ballots alternate between defaulting
to "acceptable" and to "unacceptable". Each ballot clearly states which
default it uses, and there is a place on the ballot to globally change that
default. (I doubt Chris will like this idea, but it is at least
straightforward, explicit, and easy to describe.)
Chris Benham
43: A
24: B>C
23: C>B
10: D
On 9/11/2016 4:21 PM, Jameson Quinn wrote:
I think that scenarios like the above are fundamentally pathological;
any possible winner has only minority approval, so that even assuming
all ballots are semi-honest, any of them could be a true Condorcet loser.
C: I can't see anything "pathological" about the "scenario". The ballot
set can be taken at face value. Presumably the A and D supporters
simply aren't interested in any candidate
other than their favourites, while the B and C supporters form a tight
coalition. And B is the clearly voted Condorcet winner.
Just because you can imagine that with less truncation some other
candidate could have been the Condorcet winner doesn't mean that the
scenario is in any way "pathological".
J: Thus, I believe that it's more important for a system to try to
avoid scenarios like the above, than to try to find a perfect winner
in such a scenario.
But there isn't (or shouldn't be) anything difficult about finding "the
perfect winner" in the scenario. B is the plainly voted Condorcet
winner. An Approval-like method
might mistakenly elect the "similar" candidate C, but A and D are out.
And if I agreed that a system "should try to avoid" such a scenario, I
can't see how it could (allowing 4 candidates and using ballots with 3
or more ratings slots).
43: A
40: B>C
6: C>B
1: C
10: D
J:... I think that a case can be made for either A or B. After all,
they'd be tied if we try to approximate Score by using truncatable
Borda here. But no serious case can be made for C or D, even though C
wins MTA and MCA.
The pairwise-dominant B,C coalition is still intact. Without the
irrelevant D ballots it has more than half the votes. B is still the CW,
C is the most approved ("accepted", voted above bottom)
candidate. B is also more approved than A. That adds up to no case for A.
J: After all, they'd be tied if we try to approximate Score by using
truncatable Borda here
C: In my opinion that is a bizarre and very weak standard. Those methods
don't even meet Majority Favourite, and Borda has other problems.
J: But no serious case can be made for C or D, even though C wins MTA
and MCA.
C: C is the most approved candidate and pairwise beats all the others
except B, and all of B's supporters approved of C (which arguably
somewhat weakens any post-election complaint
they might make, since MTA and MCA are quasi-Approval methods that
aren't advertised as meeting the Condorcet criterion.)
Another 3-slot FBC method I think we should be comparing with these
three is 3-slot TTR,TR (aka" ICT"). The algorithm is probably too
complicated to interest Jameson
as a practical reform proposal, but it meets Chicken Dilemma and
"Majority Condorcet" and easily elects the CW in the recent examples.
J: One possible alternative default rule: ballots alternate between
defaulting to "acceptable" and to "unacceptable". Each ballot clearly
states which default it uses, and there is a place on the ballot to
globally change that default. (I doubt Chris will like this idea, but
it is at least straightforward, explicit, and easy to describe.)
I'm strongly of the view that the voters shouldn't have to bother
explicitly marking candidates they rate as unacceptable. I suggest a
ballot instruction something like:
"Among candidates you find acceptable, mark however many you like of
your favourites as Preferred and the rest as Acceptable".
However, if there was a concern that someone might get access to the
ballots after they're cast and before they are counted and alter some by
adding marks to
candidates the voters left unmarked, then that could be justification
(or a pretext) for a draconian Australian-style solution with a ballot
instruction like:
"Mark each candidate as one of Preferred, Acceptable, Unacceptable.
You must mark every candidate."
Then ballots that don't mark every candidate are declared "invalid" and
have no effect on the election result.
One more semi-sane alternative is to have a ballot instruction like the
Australian-style one but make the default "acceptable" under MTA and MCA
and "unacceptable"
under U/P but in each case with a weight of one half in the counting.
(But of course that doesn't completely remove the incentive for some
cheater to add marks to
ballots).
Chris Benham
On 9/11/2016 4:21 PM, Jameson Quinn wrote:
2016-09-10 21:26 GMT-04:00 C.Benham <cbenham@adam.com.au
mailto:cbenham@adam.com.au>:
On 9/11/2016 5:02 AM, Kevin Venzke wrote:
43: A
24: B>C
23: C>B
10: D
Under MTA the B and C voters are being completely reasonable:
They hope for majority approval but can still hope for a win
if they
don't get it.
Strategy is less likely to produce these ballots under U/P
because the B and C voters are taking a gamble. To get a
similar outcome
they have to vote B=C. Anyone who doesn't is functionally
defecting!
C: A very good example! Assuming MTA and MCA use Top Ratings
scores to break Approval ties, they both elect the Condorcet winner B.
J: But both could be shifted to C with a single C-only ballot, even if
the B:C ratio were 46:1 instead of 24:23.
C: U/P's under-use of the middle ratings slot means that it
relies more on its "majority disqualification" mechanism which
seems to make it more
vulnerable to irrelevant ballots, as in the example.
Under U/P, without the irrelevant D ballots, A and D are
disqualified and B is the glorious winner. With them, B and C and
D are disqualified and (without needing
any others to be disqualified) A wins.
This causes me to reject U/P as clearly worse than MTA and MCA. Of
the three I (again) rate MTA as the least bad.
J: I think MTA is pretty darn good. I still prefer U/P.
I think that scenarios like the above are fundamentally pathological;
any possible winner has only minority approval, so that even assuming
all ballots are semi-honest, any of them could be a true Condorcet
loser. Thus, I believe that it's more important for a system to try to
avoid scenarios like the above, than to try to find a perfect winner
in such a scenario. In fact, in the related scenario:
43: A
40: B>C
6: C>B
1: C
10: D
... I think that a case can be made for either A or B. After all,
they'd be tied if we try to approximate Score by using truncatable
Borda here. But no serious case can be made for C or D, even though C
wins MTA and MCA.
Anyway, I think U/P does a better job trying to discourage the kind of
strategy that would lead to a scenario like the above. And part of
that is the default rule which Chris has criticized.
One possible alternative default rule: ballots alternate between
defaulting to "acceptable" and to "unacceptable". Each ballot clearly
states which default it uses, and there is a place on the ballot to
globally change that default. (I doubt Chris will like this idea, but
it is at least straightforward, explicit, and easy to describe.)
Hi Jameson,
I think it is a positive thing that the MTA B/C majority coalition can give their sincere preferences (!), while using the strategy they're expected to use (i.e. middle slot as tiebreaker given multiple majorities), without risk of this strategy backfiring. (Voters can accidentally elect the less preferred of B or C, but that is the inescapable chicken dilemma, I would say.)
I have some sympathy for your claim that C should not be able to win with few top ratings. But that sympathy is not tied to Borda counts, it is based on wanting to reduce the truncation incentive for the B voters. This, U/P does not really do, because the B>C voters would be taking a large risk that they are helping to put C (alone) over the threshold of majority approval.
So I don't think either of these ballot sets is likely under U/P, and it sounds like you agree with that and think it is good (because it deters a pathological ballot set)? Do you have a stance (or at least, see use in determining a stance) on how U/P voters in these scenarios should be voting?
Kevin
De : Jameson Quinn <jameson.quinn@gmail.com>
À : EM election-methods@lists.electorama.com
Envoyé le : Dimanche 11 septembre 2016 1h51
Objet : [EM] Fwd: Fwd: U/P voting: new name for simple 3-level method.
2016-09-10 21:26 GMT-04:00 C.Benham cbenham@adam.com.au:
On 9/11/2016 5:02 AM, Kevin Venzke wrote:
43: A
24: B>C
23: C>B
10: D
Under MTA the B and C voters are being completely reasonable: They hope for majority approval but can still hope for a win if they
don't get it.
Strategy is less likely to produce these ballots under U/P because the B and C voters are taking a gamble. To get a similar outcome
they have to vote B=C. Anyone who doesn't is functionally defecting!
C: A very good example! Assuming MTA and MCA use Top Ratings scores to break Approval ties, they both elect the Condorcet winner B.
But both could be shifted to C with a single C-only ballot, even if the B:C ratio were 46:1 instead of 24:23.
U/P's under-use of the middle ratings slot means that it relies more on its "majority disqualification" mechanism which seems to make it more
vulnerable to irrelevant ballots, as in the example.
Under U/P, without the irrelevant D ballots, A and D are disqualified and B is the glorious winner. With them, B and C and D are disqualified and (without needing
any others to be disqualified) A wins.
This causes me to reject U/P as clearly worse than MTA and MCA. Of the three I (again) rate MTA as the least bad.
I think MTA is pretty darn good. I still prefer U/P.
I think that scenarios like the above are fundamentally pathological; any possible winner has only minority approval, so that even assuming all ballots are semi-honest, any of them could be a true Condorcet loser. Thus, I believe that it's more important for a system to try to avoid scenarios like the above, than to try to find a perfect winner in such a scenario. In fact, in the related scenario:
43: A
40: B>C6: C>B
1: C
10: D
... I think that a case can be made for either A or B. After all, they'd be tied if we try to approximate Score by using truncatable Borda here. But no serious case can be made for C or D, even though C wins MTA and MCA.
Anyway, I think U/P does a better job trying to discourage the kind of strategy that would lead to a scenario like the above. And part of that is the default rule which Chris has criticized.
One possible alternative default rule: ballots alternate between defaulting to "acceptable" and to "unacceptable". Each ballot clearly states which default it uses, and there is a place on the ballot to globally change that default. (I doubt Chris will like this idea, but it is at least straightforward, explicit, and easy to describe.)
Chris Benham
Election-Methods mailing list - see http://electorama.com/em for list info
Here's a new proposed variant of U/P with a simple default:
Voters may rate each candidate as "unacceptable" (downvote), "preferred"
(upvote), or "acceptable" (neither). Default is neither.
Any candidate downvoted by most, or with fewer than half the max amount of
upvotes, is disqualified, unless that would disqualify everyone. The winner
is the remaining candidate with the most upvotes.
The "fewer than half the max" rule prevents dark-horse winners, without
resorting to strange defaults. It has no effect on a two-way chicken
dilemma. Though in theory it could affect an evenly-balanced three-way
chicken dilemma (in a four-way race), I think there's a negligible chance
that such a scenario would be so balanced.
I know that Chris doesn't like this method's violation of "irrelevant
ballots". Myself, I think that no voters are irrelevant; even if they don't
express an opinion between the two frontrunners, they may have one. (True,
they may not; but that's not the first assumption I'd make.)
2016-09-12 20:22 GMT-04:00 Kevin Venzke stepjak@yahoo.fr:
Hi Jameson,
I think it is a positive thing that the MTA B/C majority coalition can
give their sincere preferences (!), while using the strategy they're
expected to use (i.e. middle slot as tiebreaker given multiple majorities),
without risk of this strategy backfiring. (Voters can accidentally elect
the less preferred of B or C, but that is the inescapable chicken dilemma,
I would say.)
I have some sympathy for your claim that C should not be able to win with
few top ratings. But that sympathy is not tied to Borda counts, it is based
on wanting to reduce the truncation incentive for the B voters. This, U/P
does not really do, because the B>C voters would be taking a large risk
that they are helping to put C (alone) over the threshold of majority
approval.
So I don't think either of these ballot sets is likely under U/P, and it
sounds like you agree with that and think it is good (because it deters a
pathological ballot set)? Do you have a stance (or at least, see use in
determining a stance) on how U/P voters in these scenarios should be voting?
Kevin
De : Jameson Quinn jameson.quinn@gmail.com
À : EM election-methods@lists.electorama.com
Envoyé le : Dimanche 11 septembre 2016 1h51
Objet : [EM] Fwd: Fwd: U/P voting: new name for simple 3-level method.
2016-09-10 21:26 GMT-04:00 C.Benham cbenham@adam.com.au:
On 9/11/2016 5:02 AM, Kevin Venzke wrote:
43: A
24: B>C
23: C>B
10: D
Under MTA the B and C voters are being completely reasonable: They hope
for majority approval but can still hope for a win if they
don't get it.
Strategy is less likely to produce these ballots under U/P because the B
and C voters are taking a gamble. To get a similar outcome
they have to vote B=C. Anyone who doesn't is functionally defecting!
C: A very good example! Assuming MTA and MCA use Top Ratings scores to
break Approval ties, they both elect the Condorcet winner B.
But both could be shifted to C with a single C-only ballot, even if the
B:C ratio were 46:1 instead of 24:23.
U/P's under-use of the middle ratings slot means that it relies more on
its "majority disqualification" mechanism which seems to make it more
vulnerable to irrelevant ballots, as in the example.
Under U/P, without the irrelevant D ballots, A and D are disqualified and
B is the glorious winner. With them, B and C and D are disqualified and
(without needing
any others to be disqualified) A wins.
This causes me to reject U/P as clearly worse than MTA and MCA. Of the
three I (again) rate MTA as the least bad.
I think MTA is pretty darn good. I still prefer U/P.
I think that scenarios like the above are fundamentally pathological; any
possible winner has only minority approval, so that even assuming all
ballots are semi-honest, any of them could be a true Condorcet loser. Thus,
I believe that it's more important for a system to try to avoid scenarios
like the above, than to try to find a perfect winner in such a scenario. In
fact, in the related scenario:
43: A
40: B>C
6: C>B
1: C
10: D
... I think that a case can be made for either A or B. After all, they'd
be tied if we try to approximate Score by using truncatable Borda here. But
no serious case can be made for C or D, even though C wins MTA and MCA.
Anyway, I think U/P does a better job trying to discourage the kind of
strategy that would lead to a scenario like the above. And part of that is
the default rule which Chris has criticized.
One possible alternative default rule: ballots alternate between
defaulting to "acceptable" and to "unacceptable". Each ballot clearly
states which default it uses, and there is a place on the ballot to
globally change that default. (I doubt Chris will like this idea, but it is
at least straightforward, explicit, and easy to describe.)
Chris Benham
Election-Methods mailing list - see http://electorama.com/em for list info
Hi Jameson,
"Downvoted by most" means the candidate with the single greatest number of downvotes? This could be the (voted, unique) majority favorite couldn't it?
How does this violate "irrelevant ballots"? I must be misunderstanding it. Does "max amount of upvotes" mean 100% of the voters, or just the greatest number of upvotes that occurs?
I do like antiplurality mechanisms.
Kevin
De : Jameson Quinn <jameson.quinn@gmail.com>
À : Kevin Venzke stepjak@yahoo.fr; electionsciencefoundation electionscience@googlegroups.com
Cc : EM election-methods@lists.electorama.com
Envoyé le : Lundi 12 septembre 2016 20h37
Objet : Re: [EM] Fwd: Fwd: U/P voting: new name for simple 3-level method.
Here's a new proposed variant of U/P with a simple default:
Voters may rate each candidate as "unacceptable" (downvote), "preferred" (upvote), or "acceptable" (neither). Default is neither.
Any candidate downvoted by most, or with fewer than half the max amount of upvotes, is disqualified, unless that would disqualify everyone. The winner is the remaining candidate with the most upvotes.
The "fewer than half the max" rule prevents dark-horse winners, without resorting to strange defaults. It has no effect on a two-way chicken dilemma. Though in theory it could affect an evenly-balanced three-way chicken dilemma (in a four-way race), I think there's a negligible chance that such a scenario would be so balanced.
I know that Chris doesn't like this method's violation of "irrelevant ballots". Myself, I think that no voters are irrelevant; even if they don't express an opinion between the two frontrunners, they may have one. (True, they may not; but that's not the first assumption I'd make.)
2016-09-12 20:22 GMT-04:00 Kevin Venzke stepjak@yahoo.fr:
Hi Jameson,
I think it is a positive thing that the MTA B/C majority coalition can give their sincere preferences (!), while using the strategy they're expected to use (i.e. middle slot as tiebreaker given multiple majorities), without risk of this strategy backfiring. (Voters can accidentally elect the less preferred of B or C, but that is the inescapable chicken dilemma, I would say.)
I have some sympathy for your claim that C should not be able to win with few top ratings. But that sympathy is not tied to Borda counts, it is based on wanting to reduce the truncation incentive for the B voters. This, U/P does not really do, because the B>C voters would be taking a large risk that they are helping to put C (alone) over the threshold of majority approval.
So I don't think either of these ballot sets is likely under U/P, and it sounds like you agree with that and think it is good (because it deters a pathological ballot set)? Do you have a stance (or at least, see use in determining a stance) on how U/P voters in these scenarios should be voting?
Kevin
De : Jameson Quinn <jameson.quinn@gmail.com>
À : EM <election-methods@lists. electorama.com>
Envoyé le : Dimanche 11 septembre 2016 1h51
Objet : [EM] Fwd: Fwd: U/P voting: new name for simple 3-level method.
2016-09-10 21:26 GMT-04:00 C.Benham cbenham@adam.com.au:
On 9/11/2016 5:02 AM, Kevin Venzke wrote:
43: A
24: B>C
23: C>B
10: D
Under MTA the B and C voters are being completely reasonable: They hope for majority approval but can still hope for a win if they
don't get it.
Strategy is less likely to produce these ballots under U/P because the B and C voters are taking a gamble. To get a similar outcome
they have to vote B=C. Anyone who doesn't is functionally defecting!
C: A very good example! Assuming MTA and MCA use Top Ratings scores to break Approval ties, they both elect the Condorcet winner B.
But both could be shifted to C with a single C-only ballot, even if the B:C ratio were 46:1 instead of 24:23.
U/P's under-use of the middle ratings slot means that it relies more on its "majority disqualification" mechanism which seems to make it more
vulnerable to irrelevant ballots, as in the example.
Under U/P, without the irrelevant D ballots, A and D are disqualified and B is the glorious winner. With them, B and C and D are disqualified and (without needing
any others to be disqualified) A wins.
This causes me to reject U/P as clearly worse than MTA and MCA. Of the three I (again) rate MTA as the least bad.
I think MTA is pretty darn good. I still prefer U/P.
I think that scenarios like the above are fundamentally pathological; any possible winner has only minority approval, so that even assuming all ballots are semi-honest, any of them could be a true Condorcet loser. Thus, I believe that it's more important for a system to try to avoid scenarios like the above, than to try to find a perfect winner in such a scenario. In fact, in the related scenario:
43: A
40: B>C6: C>B
1: C
10: D
... I think that a case can be made for either A or B. After all, they'd be tied if we try to approximate Score by using truncatable Borda here. But no serious case can be made for C or D, even though C wins MTA and MCA.
Anyway, I think U/P does a better job trying to discourage the kind of strategy that would lead to a scenario like the above. And part of that is the default rule which Chris has criticized.
One possible alternative default rule: ballots alternate between defaulting to "acceptable" and to "unacceptable". Each ballot clearly states which default it uses, and there is a place on the ballot to globally change that default. (I doubt Chris will like this idea, but it is at least straightforward, explicit, and easy to describe.)
Chris Benham
Election-Methods mailing list - see http://electorama.com/em for list info
Election-Methods mailing list - see http://electorama.com/em for list info
Kevin,
I take "downvoted by most" to mean down-voted by most of the voters,
meaning down-voted on more than half the ballots.
Your interpretation would be "the most downvoted".
Chris Benham
On 9/13/2016 2:56 PM, Kevin Venzke wrote:
Hi Jameson,
"Downvoted by most" means the candidate with the single greatest
number of downvotes? This could be the (voted, unique) majority
favorite couldn't it?
How does this violate "irrelevant ballots"? I must be misunderstanding
it. Does "max amount of upvotes" mean 100% of the voters, or just the
greatest number of upvotes that occurs?
I do like antiplurality mechanisms.
Kevin
De : Jameson Quinn jameson.quinn@gmail.com
À : Kevin Venzke stepjak@yahoo.fr; electionsciencefoundation
electionscience@googlegroups.com
Cc : EM election-methods@lists.electorama.com
Envoyé le : Lundi 12 septembre 2016 20h37
Objet : Re: [EM] Fwd: Fwd: U/P voting: new name for simple 3-level
method.
Here's a new proposed variant of U/P with a simple default:
Voters may rate each candidate as "unacceptable" (downvote),
"preferred" (upvote), or "acceptable" (neither). Default is neither.
Any candidate downvoted by most, or with fewer than half the max
amount of upvotes, is disqualified, unless that would disqualify
everyone. The winner is the remaining candidate with the most upvotes.
The "fewer than half the max" rule prevents dark-horse winners,
without resorting to strange defaults. It has no effect on a two-way
chicken dilemma. Though in theory it could affect an evenly-balanced
three-way chicken dilemma (in a four-way race), I think there's a
negligible chance that such a scenario would be so balanced.
I know that Chris doesn't like this method's violation of "irrelevant
ballots". Myself, I think that no voters are irrelevant; even if they
don't express an opinion between the two frontrunners, they may have
one. (True, they may not; but that's not the first assumption I'd make.)
2016-09-12 20:22 GMT-04:00 Kevin Venzke <stepjak@yahoo.fr
mailto:stepjak@yahoo.fr>:
Hi Jameson,
I think it is a positive thing that the MTA B/C majority coalition
can give their sincere preferences (!), while using the strategy
they're expected to use (i.e. middle slot as tiebreaker given
multiple majorities), without risk of this strategy backfiring.
(Voters can accidentally elect the less preferred of B or C, but
that is the inescapable chicken dilemma, I would say.)
I have some sympathy for your claim that C should not be able to
win with few top ratings. But that sympathy is not tied to Borda
counts, it is based on wanting to reduce the truncation incentive
for the B voters. This, U/P does not really do, because the B>C
voters would be taking a large risk that they are helping to put C
(alone) over the threshold of majority approval.
So I don't think either of these ballot sets is likely under U/P,
and it sounds like you agree with that and think it is good
(because it deters a pathological ballot set)? Do you have a
stance (or at least, see use in determining a stance) on how U/P
voters in these scenarios should be voting?
Kevin
------------------------------------------------------------------------
*De :* Jameson Quinn <jameson.quinn@gmail.com
<mailto:jameson.quinn@gmail.com>>
*À :* EM <election-methods@lists. electorama.com
<mailto:election-methods@lists.electorama.com>>
*Envoyé le :* Dimanche 11 septembre 2016 1h51
*Objet :* [EM] Fwd: Fwd: U/P voting: new name for simple 3-level
method.
2016-09-10 21:26 GMT-04:00 C.Benham <cbenham@adam.com.au
<mailto:cbenham@adam.com.au>>:
On 9/11/2016 5:02 AM, Kevin Venzke wrote:
43: A
24: B>C
23: C>B
10: D
Under MTA the B and C voters are being completely
reasonable: They hope for majority approval but can still
hope for a win if they
don't get it.
Strategy is less likely to produce these ballots under U/P
because the B and C voters are taking a gamble. To get a
similar outcome
they have to vote B=C. Anyone who doesn't is functionally
defecting!
C: A very good example! Assuming MTA and MCA use Top Ratings
scores to break Approval ties, they both elect the Condorcet
winner B.
But both could be shifted to C with a single C-only ballot, even
if the B:C ratio were 46:1 instead of 24:23.
U/P's under-use of the middle ratings slot means that it
relies more on its "majority disqualification" mechanism which
seems to make it more
vulnerable to irrelevant ballots, as in the example.
Under U/P, without the irrelevant D ballots, A and D are
disqualified and B is the glorious winner. With them, B and C
and D are disqualified and (without needing
any others to be disqualified) A wins.
This causes me to reject U/P as clearly worse than MTA and
MCA. Of the three I (again) rate MTA as the least bad.
I think MTA is pretty darn good. I still prefer U/P.
I think that scenarios like the above are fundamentally
pathological; any possible winner has only minority approval, so
that even assuming all ballots are semi-honest, any of them could
be a true Condorcet loser. Thus, I believe that it's more
important for a system to try to avoid scenarios like the above,
than to try to find a perfect winner in such a scenario. In fact,
in the related scenario:
43: A
40: B>C
6: C>B
1: C
10: D
... I think that a case can be made for either A or B. After all,
they'd be tied if we try to approximate Score by using truncatable
Borda here. But no serious case can be made for C or D, even
though C wins MTA and MCA.
Anyway, I think U/P does a better job trying to discourage the
kind of strategy that would lead to a scenario like the above. And
part of that is the default rule which Chris has criticized.
One possible alternative default rule: ballots alternate between
defaulting to "acceptable" and to "unacceptable". Each ballot
clearly states which default it uses, and there is a place on the
ballot to globally change that default. (I doubt Chris will like
this idea, but it is at least straightforward, explicit, and easy
to describe.)
Chris Benham
----
Election-Methods mailing list - see http://electorama.com/em for
list info
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Chris is correct. "by most" = "by a majority". Maximum is "the most".
Perhaps I should avoid that word, but I was trying to use small words, as
in Randall Munroe's "Thing Explainer".
2016-09-13 6:28 GMT-04:00 C.Benham cbenham@adam.com.au:
Kevin,
I take "downvoted by most" to mean down-voted by most of the voters,
meaning down-voted on more than half the ballots.
Your interpretation would be "the most downvoted".
Chris Benham
On 9/13/2016 2:56 PM, Kevin Venzke wrote:
Hi Jameson,
"Downvoted by most" means the candidate with the single greatest number of
downvotes? This could be the (voted, unique) majority favorite couldn't it?
How does this violate "irrelevant ballots"? I must be misunderstanding it.
Does "max amount of upvotes" mean 100% of the voters, or just the greatest
number of upvotes that occurs?
I do like antiplurality mechanisms.
Kevin
De : Jameson Quinn jameson.quinn@gmail.com jameson.quinn@gmail.com
À : Kevin Venzke stepjak@yahoo.fr stepjak@yahoo.fr;
electionsciencefoundation electionscience@googlegroups.com
electionscience@googlegroups.com
Cc : EM election-methods@lists.electorama.com
election-methods@lists.electorama.com
Envoyé le : Lundi 12 septembre 2016 20h37
Objet : Re: [EM] Fwd: Fwd: U/P voting: new name for simple 3-level
method.
Here's a new proposed variant of U/P with a simple default:
Voters may rate each candidate as "unacceptable" (downvote), "preferred"
(upvote), or "acceptable" (neither). Default is neither.
Any candidate downvoted by most, or with fewer than half the max amount of
upvotes, is disqualified, unless that would disqualify everyone. The winner
is the remaining candidate with the most upvotes.
The "fewer than half the max" rule prevents dark-horse winners, without
resorting to strange defaults. It has no effect on a two-way chicken
dilemma. Though in theory it could affect an evenly-balanced three-way
chicken dilemma (in a four-way race), I think there's a negligible chance
that such a scenario would be so balanced.
I know that Chris doesn't like this method's violation of "irrelevant
ballots". Myself, I think that no voters are irrelevant; even if they don't
express an opinion between the two frontrunners, they may have one. (True,
they may not; but that's not the first assumption I'd make.)
2016-09-12 20:22 GMT-04:00 Kevin Venzke stepjak@yahoo.fr:
Hi Jameson,
I think it is a positive thing that the MTA B/C majority coalition can
give their sincere preferences (!), while using the strategy they're
expected to use (i.e. middle slot as tiebreaker given multiple majorities),
without risk of this strategy backfiring. (Voters can accidentally elect
the less preferred of B or C, but that is the inescapable chicken dilemma,
I would say.)
I have some sympathy for your claim that C should not be able to win with
few top ratings. But that sympathy is not tied to Borda counts, it is based
on wanting to reduce the truncation incentive for the B voters. This, U/P
does not really do, because the B>C voters would be taking a large risk
that they are helping to put C (alone) over the threshold of majority
approval.
So I don't think either of these ballot sets is likely under U/P, and it
sounds like you agree with that and think it is good (because it deters a
pathological ballot set)? Do you have a stance (or at least, see use in
determining a stance) on how U/P voters in these scenarios should be voting?
Kevin
De : Jameson Quinn jameson.quinn@gmail.com
À : EM <election-methods@lists. electorama.com
election-methods@lists.electorama.com>
Envoyé le : Dimanche 11 septembre 2016 1h51
Objet : [EM] Fwd: Fwd: U/P voting: new name for simple 3-level method.
2016-09-10 21:26 GMT-04:00 C.Benham cbenham@adam.com.au:
On 9/11/2016 5:02 AM, Kevin Venzke wrote:
43: A
24: B>C
23: C>B
10: D
Under MTA the B and C voters are being completely reasonable: They hope
for majority approval but can still hope for a win if they
don't get it.
Strategy is less likely to produce these ballots under U/P because the B
and C voters are taking a gamble. To get a similar outcome
they have to vote B=C. Anyone who doesn't is functionally defecting!
C: A very good example! Assuming MTA and MCA use Top Ratings scores to
break Approval ties, they both elect the Condorcet winner B.
But both could be shifted to C with a single C-only ballot, even if the
B:C ratio were 46:1 instead of 24:23.
U/P's under-use of the middle ratings slot means that it relies more on
its "majority disqualification" mechanism which seems to make it more
vulnerable to irrelevant ballots, as in the example.
Under U/P, without the irrelevant D ballots, A and D are disqualified and
B is the glorious winner. With them, B and C and D are disqualified and
(without needing
any others to be disqualified) A wins.
This causes me to reject U/P as clearly worse than MTA and MCA. Of the
three I (again) rate MTA as the least bad.
I think MTA is pretty darn good. I still prefer U/P.
I think that scenarios like the above are fundamentally pathological; any
possible winner has only minority approval, so that even assuming all
ballots are semi-honest, any of them could be a true Condorcet loser. Thus,
I believe that it's more important for a system to try to avoid scenarios
like the above, than to try to find a perfect winner in such a scenario. In
fact, in the related scenario:
43: A
40: B>C
6: C>B
1: C
10: D
... I think that a case can be made for either A or B. After all, they'd
be tied if we try to approximate Score by using truncatable Borda here. But
no serious case can be made for C or D, even though C wins MTA and MCA.
Anyway, I think U/P does a better job trying to discourage the kind of
strategy that would lead to a scenario like the above. And part of that is
the default rule which Chris has criticized.
One possible alternative default rule: ballots alternate between
defaulting to "acceptable" and to "unacceptable". Each ballot clearly
states which default it uses, and there is a place on the ballot to
globally change that default. (I doubt Chris will like this idea, but it is
at least straightforward, explicit, and easy to describe.)
Chris Benham
Election-Methods mailing list - see http://electorama.com/em for list info
Election-Methods mailing list - see http://electorama.com/em for list info
Election-Methods mailing list - see http://electorama.com/em for list info
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Election-Methods mailing list - see http://electorama.com/em for list info
And I took " the max amount of upvotes" to refer to the maximum number
of up-votes received by any candidate.
Chris Benham
On 9/13/2016 10:31 PM, Jameson Quinn wrote:
Chris is correct. "by most" = "by a majority". Maximum is "/the/ most".
Perhaps I should avoid that word, but I was trying to use small words,
as in Randall Munroe's "Thing Explainer".
2016-09-13 6:28 GMT-04:00 C.Benham <cbenham@adam.com.au
mailto:cbenham@adam.com.au>:
Kevin,
I take "downvoted by most" to mean down-voted by most of the
voters, meaning down-voted on more than half the ballots.
Your interpretation would be "the most downvoted".
Chris Benham
On 9/13/2016 2:56 PM, Kevin Venzke wrote:
Hi Jameson,
"Downvoted by most" means the candidate with the single greatest
number of downvotes? This could be the (voted, unique) majority
favorite couldn't it?
How does this violate "irrelevant ballots"? I must be
misunderstanding it. Does "max amount of upvotes" mean 100% of
the voters, or just the greatest number of upvotes that occurs?
I do like antiplurality mechanisms.
Kevin
------------------------------------------------------------------------
*De :* Jameson Quinn <jameson.quinn@gmail.com>
<mailto:jameson.quinn@gmail.com>
*À :* Kevin Venzke <stepjak@yahoo.fr> <mailto:stepjak@yahoo.fr>;
electionsciencefoundation <electionscience@googlegroups.com>
<mailto:electionscience@googlegroups.com>
*Cc :* EM <election-methods@lists.electorama.com>
<mailto:election-methods@lists.electorama.com>
*Envoyé le :* Lundi 12 septembre 2016 20h37
*Objet :* Re: [EM] Fwd: Fwd: U/P voting: new name for simple
3-level method.
Here's a new proposed variant of U/P with a simple default:
Voters may rate each candidate as "unacceptable" (downvote),
"preferred" (upvote), or "acceptable" (neither). Default is neither.
Any candidate downvoted by most, or with fewer than half the max
amount of upvotes, is disqualified, unless that would disqualify
everyone. The winner is the remaining candidate with the most
upvotes.
The "fewer than half the max" rule prevents dark-horse winners,
without resorting to strange defaults. It has no effect on a
two-way chicken dilemma. Though in theory it could affect an
evenly-balanced three-way chicken dilemma (in a four-way race), I
think there's a negligible chance that such a scenario would be
so balanced.
I know that Chris doesn't like this method's violation of
"irrelevant ballots". Myself, I think that no voters are
irrelevant; even if they don't express an opinion between the two
frontrunners, they may have one. (True, they may not; but that's
not the first assumption I'd make.)
2016-09-12 20:22 GMT-04:00 Kevin Venzke <stepjak@yahoo.fr
<mailto:stepjak@yahoo.fr>>:
Hi Jameson,
I think it is a positive thing that the MTA B/C majority
coalition can give their sincere preferences (!), while using
the strategy they're expected to use (i.e. middle slot as
tiebreaker given multiple majorities), without risk of this
strategy backfiring. (Voters can accidentally elect the less
preferred of B or C, but that is the inescapable chicken
dilemma, I would say.)
I have some sympathy for your claim that C should not be able
to win with few top ratings. But that sympathy is not tied to
Borda counts, it is based on wanting to reduce the truncation
incentive for the B voters. This, U/P does not really do,
because the B>C voters would be taking a large risk that they
are helping to put C (alone) over the threshold of majority
approval.
So I don't think either of these ballot sets is likely under
U/P, and it sounds like you agree with that and think it is
good (because it deters a pathological ballot set)? Do you
have a stance (or at least, see use in determining a stance)
on how U/P voters in these scenarios should be voting?
Kevin
------------------------------------------------------------------------
*De :* Jameson Quinn <jameson.quinn@gmail.com
<mailto:jameson.quinn@gmail.com>>
*À :* EM <election-methods@lists. electorama.com
<mailto:election-methods@lists.electorama.com>>
*Envoyé le :* Dimanche 11 septembre 2016 1h51
*Objet :* [EM] Fwd: Fwd: U/P voting: new name for simple
3-level method.
2016-09-10 21:26 GMT-04:00 C.Benham <cbenham@adam.com.au
<mailto:cbenham@adam.com.au>>:
On 9/11/2016 5:02 AM, Kevin Venzke wrote:
43: A
24: B>C
23: C>B
10: D
Under MTA the B and C voters are being completely
reasonable: They hope for majority approval but can
still hope for a win if they
don't get it.
Strategy is less likely to produce these ballots
under U/P because the B and C voters are taking a
gamble. To get a similar outcome
they have to vote B=C. Anyone who doesn't is
functionally defecting!
C: A very good example! Assuming MTA and MCA use Top
Ratings scores to break Approval ties, they both elect
the Condorcet winner B.
But both could be shifted to C with a single C-only ballot,
even if the B:C ratio were 46:1 instead of 24:23.
U/P's under-use of the middle ratings slot means that it
relies more on its "majority disqualification" mechanism
which seems to make it more
vulnerable to irrelevant ballots, as in the example.
Under U/P, without the irrelevant D ballots, A and D are
disqualified and B is the glorious winner. With them, B
and C and D are disqualified and (without needing
any others to be disqualified) A wins.
This causes me to reject U/P as clearly worse than MTA
and MCA. Of the three I (again) rate MTA as the least bad.
I think MTA is pretty darn good. I still prefer U/P.
I think that scenarios like the above are fundamentally
pathological; any possible winner has only minority approval,
so that even assuming all ballots are semi-honest, any of
them could be a true Condorcet loser. Thus, I believe that
it's more important for a system to try to avoid scenarios
like the above, than to try to find a perfect winner in such
a scenario. In fact, in the related scenario:
43: A
40: B>C
6: C>B
1: C
10: D
... I think that a case can be made for either A or B. After
all, they'd be tied if we try to approximate Score by using
truncatable Borda here. But no serious case can be made for C
or D, even though C wins MTA and MCA.
Anyway, I think U/P does a better job trying to discourage
the kind of strategy that would lead to a scenario like the
above. And part of that is the default rule which Chris has
criticized.
One possible alternative default rule: ballots alternate
between defaulting to "acceptable" and to "unacceptable".
Each ballot clearly states which default it uses, and there
is a place on the ballot to globally change that default. (I
doubt Chris will like this idea, but it is at least
straightforward, explicit, and easy to describe.)
Chris Benham
----
Election-Methods mailing list - see http://electorama.com/em
<http://electorama.com/em>for list info
----
Election-Methods mailing list - see http://electorama.com/em for
list info
----
Election-Methods mailing list - seehttp://electorama.com/em for list info
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Again, correct.
2016-09-13 9:17 GMT-04:00 C.Benham cbenham@adam.com.au:
And I took " the max amount of upvotes" to refer to the maximum number of
up-votes received by any candidate.
Chris Benham
On 9/13/2016 10:31 PM, Jameson Quinn wrote:
Chris is correct. "by most" = "by a majority". Maximum is "the most".
Perhaps I should avoid that word, but I was trying to use small words, as
in Randall Munroe's "Thing Explainer".
2016-09-13 6:28 GMT-04:00 C.Benham cbenham@adam.com.au:
Kevin,
I take "downvoted by most" to mean down-voted by most of the voters,
meaning down-voted on more than half the ballots.
Your interpretation would be "the most downvoted".
Chris Benham
On 9/13/2016 2:56 PM, Kevin Venzke wrote:
Hi Jameson,
"Downvoted by most" means the candidate with the single greatest number
of downvotes? This could be the (voted, unique) majority favorite couldn't
it?
How does this violate "irrelevant ballots"? I must be misunderstanding
it. Does "max amount of upvotes" mean 100% of the voters, or just the
greatest number of upvotes that occurs?
I do like antiplurality mechanisms.
Kevin
De : Jameson Quinn jameson.quinn@gmail.com jameson.quinn@gmail.com
À : Kevin Venzke stepjak@yahoo.fr stepjak@yahoo.fr;
electionsciencefoundation electionscience@googlegroups.com
electionscience@googlegroups.com
Cc : EM election-methods@lists.electorama.com
election-methods@lists.electorama.com
Envoyé le : Lundi 12 septembre 2016 20h37
Objet : Re: [EM] Fwd: Fwd: U/P voting: new name for simple 3-level
method.
Here's a new proposed variant of U/P with a simple default:
Voters may rate each candidate as "unacceptable" (downvote), "preferred"
(upvote), or "acceptable" (neither). Default is neither.
Any candidate downvoted by most, or with fewer than half the max amount
of upvotes, is disqualified, unless that would disqualify everyone. The
winner is the remaining candidate with the most upvotes.
The "fewer than half the max" rule prevents dark-horse winners, without
resorting to strange defaults. It has no effect on a two-way chicken
dilemma. Though in theory it could affect an evenly-balanced three-way
chicken dilemma (in a four-way race), I think there's a negligible chance
that such a scenario would be so balanced.
I know that Chris doesn't like this method's violation of "irrelevant
ballots". Myself, I think that no voters are irrelevant; even if they don't
express an opinion between the two frontrunners, they may have one. (True,
they may not; but that's not the first assumption I'd make.)
2016-09-12 20:22 GMT-04:00 Kevin Venzke stepjak@yahoo.fr:
Hi Jameson,
I think it is a positive thing that the MTA B/C majority coalition can
give their sincere preferences (!), while using the strategy they're
expected to use (i.e. middle slot as tiebreaker given multiple majorities),
without risk of this strategy backfiring. (Voters can accidentally elect
the less preferred of B or C, but that is the inescapable chicken dilemma,
I would say.)
I have some sympathy for your claim that C should not be able to win with
few top ratings. But that sympathy is not tied to Borda counts, it is based
on wanting to reduce the truncation incentive for the B voters. This, U/P
does not really do, because the B>C voters would be taking a large risk
that they are helping to put C (alone) over the threshold of majority
approval.
So I don't think either of these ballot sets is likely under U/P, and it
sounds like you agree with that and think it is good (because it deters a
pathological ballot set)? Do you have a stance (or at least, see use in
determining a stance) on how U/P voters in these scenarios should be voting?
Kevin
De : Jameson Quinn jameson.quinn@gmail.com
À : EM <election-methods@lists. electorama.com
election-methods@lists.electorama.com>
Envoyé le : Dimanche 11 septembre 2016 1h51
Objet : [EM] Fwd: Fwd: U/P voting: new name for simple 3-level method.
2016-09-10 21:26 GMT-04:00 C.Benham cbenham@adam.com.au:
On 9/11/2016 5:02 AM, Kevin Venzke wrote:
43: A
24: B>C
23: C>B
10: D
Under MTA the B and C voters are being completely reasonable: They hope
for majority approval but can still hope for a win if they
don't get it.
Strategy is less likely to produce these ballots under U/P because the B
and C voters are taking a gamble. To get a similar outcome
they have to vote B=C. Anyone who doesn't is functionally defecting!
C: A very good example! Assuming MTA and MCA use Top Ratings scores to
break Approval ties, they both elect the Condorcet winner B.
But both could be shifted to C with a single C-only ballot, even if the
B:C ratio were 46:1 instead of 24:23.
U/P's under-use of the middle ratings slot means that it relies more on
its "majority disqualification" mechanism which seems to make it more
vulnerable to irrelevant ballots, as in the example.
Under U/P, without the irrelevant D ballots, A and D are disqualified and
B is the glorious winner. With them, B and C and D are disqualified and
(without needing
any others to be disqualified) A wins.
This causes me to reject U/P as clearly worse than MTA and MCA. Of the
three I (again) rate MTA as the least bad.
I think MTA is pretty darn good. I still prefer U/P.
I think that scenarios like the above are fundamentally pathological; any
possible winner has only minority approval, so that even assuming all
ballots are semi-honest, any of them could be a true Condorcet loser. Thus,
I believe that it's more important for a system to try to avoid scenarios
like the above, than to try to find a perfect winner in such a scenario. In
fact, in the related scenario:
43: A
40: B>C
6: C>B
1: C
10: D
... I think that a case can be made for either A or B. After all, they'd
be tied if we try to approximate Score by using truncatable Borda here. But
no serious case can be made for C or D, even though C wins MTA and MCA.
Anyway, I think U/P does a better job trying to discourage the kind of
strategy that would lead to a scenario like the above. And part of that is
the default rule which Chris has criticized.
One possible alternative default rule: ballots alternate between
defaulting to "acceptable" and to "unacceptable". Each ballot clearly
states which default it uses, and there is a place on the ballot to
globally change that default. (I doubt Chris will like this idea, but it is
at least straightforward, explicit, and easy to describe.)
Chris Benham
Election-Methods mailing list - see http://electorama.com/em for list
info
Election-Methods mailing list - see http://electorama.com/em for list
info
Election-Methods mailing list - see http://electorama.com/em for list info
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There is also the potential problem - as Chris Benham mentioned previously
- that the default vote is not the bottom rating. Arguably most people who
know how the system works would simply bottom rate candidates as their
default move if they aren't actively positively inclined towards them.
Others who aren't as familiar with the inner workings might not do this, so
arguably it makes it a bit of a two-tier system for voters. And that could
be seen as a failure of simplicity.
On Tuesday, 13 September 2016 02:38:04 UTC+1, Jameson Quinn wrote:
Here's a new proposed variant of U/P with a simple default:
Voters may rate each candidate as "unacceptable" (downvote), "preferred"
(upvote), or "acceptable" (neither). Default is neither.
Any candidate downvoted by most, or with fewer than half the max amount of
upvotes, is disqualified, unless that would disqualify everyone. The winner
is the remaining candidate with the most upvotes.
The "fewer than half the max" rule prevents dark-horse winners, without
resorting to strange defaults. It has no effect on a two-way chicken
dilemma. Though in theory it could affect an evenly-balanced three-way
chicken dilemma (in a four-way race), I think there's a negligible chance
that such a scenario would be so balanced.
I know that Chris doesn't like this method's violation of "irrelevant
ballots". Myself, I think that no voters are irrelevant; even if they don't
express an opinion between the two frontrunners, they may have one. (True,
they may not; but that's not the first assumption I'd make.)