STAR
Toby,
But it is still interesting that STAR does well in Jameson's simulations.
Not to me, or not in any way that reflects positively on STAR.
As for what the boxes are about, they are about ensuring that voting
methods have sensible behaviour in certain situations, so I wouldn't
expect them to necessarily negatively correlate with a "good" result.
Then you are not using the right boxes.
It's what I just replied to Kristofer - the fact that there's no way
that you can consistently define society's preference in a way that
you can determine whether society prefers A or B by looking at the
pairwise comparison.
Then what do you "look at" ??
One of the reasons I bring this up is that there are some people who
think that only a Condorcet method could even be considered democratic.
I am not entirely in that camp, only because meeting the Condorcet
criterion is "expensive". All Condorcet methods have some Burial
incentive (fail Later-no-Help) and fail Favourite Betrayal.
So I consider some methods that don't have one of those problems to be
acceptable.
I would counter this by saying that it's based on this logical
contradiction.
I'm still not seeing this "logical contradiction".
I would also counter it by saying that someone could equally say
(perhaps have a greater claim) that a method cannot be democratic if
it fails participation
I don't see that either. So which method that meets Participation do you
like?
Two of the main ones I tend to look out for are monotonicity and
independence of clones because they are obviously things we would want
and they don't seem to be too restrictive in terms of methods they allow
STAR fails both of them, "badly".
STAR is obviously garbage and a strategy farce, as I'll explain later
on EM.
Chris
On 14/08/2023 6:11 pm, Toby Pereira wrote:
On Monday, 14 August 2023 at 05:09:31 BST, C.Benham
cbenham@adam.com.au wrote:
Toby wrote:
I think this is an interesting point. We can ask at a
philosophical level what makes a good voting method. Is it just one
that ticks the most boxes, or is it one >>that most reliably gets the
"best" result?
Toby,
How are those two counter-posed? What do you think "the boxes" are
about?
I mentioned that there could be multiple low-level failures versus a
few high-level failures, but also that it was a fairly hypothetical
discussion. I'm not of the view that because of Jameson Quinn's
simulations, it must be the case that the only way to get the best
results is to sacrifice the strict passing of criteria. However, if we
do define best in terms of utility or the median voter, I'm agnostic
as to what method would best get these results in practice. But it is
still interesting that STAR does well in Jameson's simulations. As for
what the boxes are about, they are about ensuring that voting methods
have sensible behaviour in certain situations, so I wouldn't expect
them to necessarily negatively correlate with a "good" result.
And that's partly because the premise of Condorcet is essentially
built on a logical fallacy - basically that if A is preferred to B on
more ballots that vice versa >>then electing A must
be a better result than electing B.
I'd be interested in reading your explanation of why you think that is a
"logical fallacy". What about if there are only two candidates?
It's what I just replied to Kristofer - the fact that there's no way
that you can consistently define society's preference in a way that
you can determine whether society prefers A or B by looking at the
pairwise comparison. It also doesn't make any difference if there are
only two candidates. It's just that with two candidates, you won't
notice it. If A and B are the only two candidates, then A might
pairwise beat B and get elected. But if C also stood, B might be the
winner under any of the sensible Condorcet methods that people on this
mailing list consider. So is A preferred to B or vice versa? And is it
the same answer regardless of whether C stood? Also if C was unsure
about standing but ultimately did, how would we view the creation of a
cycle? Would we say that it's bad that it messed up our majoritarian
ideals? Or would we say that it's good because it gave us more
information overall, and with this extra information B was ultimately
rightly selected over A?
One of the reasons I bring this up is that there are some people who
think that only a Condorcet method could even be considered
democratic. I would counter this by saying that it's based on this
logical contradiction. I would also counter it by saying that someone
could equally say (perhaps have a greater claim) that a method cannot
be democratic if it fails participation. This isn't to say that I
don't like Condorcet methods, but I don't think it's a good idea to
have them on a pedestal when discussing the best method to use in a
situation. They are not the last word in democracy.
I think generally while passing certain criteria is a good thing,..
Which ones do you have in mind?
Two of the main ones I tend to look out for are monotonicity and
independence of clones because they are obviously things we would want
and they don't seem to be too restrictive in terms of methods they
allow. But then with monotonicity, there is a family of criteria in
addition to the "standard" one, some of which might be more
restrictive than others. One criterion that I consider to be largely a
box-ticking exercise is Local Independence of Irrelevant Alternatives.
But other criteria such as participation and Independence of
Irrelevant Alternatives look great in the abstract, but are very
restrictive in terms of what they allow. Well, even methods that
supposedly pass IIA in theory (e.g. approval, score) in no way pass
them in practice.
Chris B.
Toby
On Tuesday, 15 August 2023 at 06:28:51 BST, C.Benham <cbenham@adam.com.au> wrote:
As for what the boxes are about, they are about ensuring that voting methods have sensible behaviour in certain situations, so I wouldn't expect them to >>necessarily negatively correlate with a "good" result.
Then you are not using the right boxes.
I think you probably misread my sentence. I would not expect them to negatively correlate with a good result. So I probably would expect passing criteria to correlate positively with a good result. Apologies for the convoluted sentence.
It's what I just replied to Kristofer - the fact that there's no way that you can consistently define society's preference in a way that you can determine whether >>society prefers A or B by looking at the pairwise comparison.
Then what do you "look at" ??
There's different things you can look at. But what I said is true, not just my opinion, so it's a question for everyone. But you can still look at pairwise comparisons and indeed use a Condorcet method. But I'd want someone to come to this by evaluating various methods and deciding that this is the best compromise overall, rather than deciding from the outset that this is the One True Way. I'm not anti-Condorcet, if this is how it's come across.
I would counter this by saying that it's based on this logical contradiction.
I'm still not seeing this "logical contradiction".
It's just the premise that if A pairwise beats B then society must prefer A to B. But it makes no sense to say that society prefers A to B, B to C and C to A. I don't think this is controversial. It's a centuries-old realisation.
I would also counter it by saying that someone could equally say (perhaps have a greater claim) that a method cannot be democratic if it fails participation
I don't see that either. So which method that meets Participation do you like?
I do actually like both score and approval. I like their simplicity and the fact that a complete numerical results list can be published that's simple and easy to understand. And I like the fact that there's no hidden weird paradoxes in either method. Any criterion they fail is pretty obvious.
My absolute favourite method isn't suitable for many elections because it has to be done online, but would be suitable for votes in online communities etc. It's approval voting but where the current scores are visible and where a voter can change their vote as much as they like until the deadline. But because co-ordinated factions might try to mess with this by voting or changing their vote at the last minute, I think a non-deterministic end point might be necessary. So you might have a week of voting plus and end section that has a half life of one hour. There may be a sense in which this fails participation though because with perfect game theoretical voting it should become Condorcet. However, this is likely to be from other voters' reactions to your presence in the voting procedure rather than you voting against your own interests. This is a fairly nebulous failure and one I could easily tolerate for a clean results table and a transparent and simple method. Also it might in practice not always elect the Condorcet winner if the Condorcet winner isn't particularly liked. E.g.
49 voters: A>>C>B49 voters: B>>C>A2 voters: C>A>B
C (the Condorcet winner) is unlikely to get off the ground in the first place in this case.
Two of the main ones I tend to look out for are monotonicity and independence of clones because they are obviously things we would want and they don't >>seem to be too restrictive in terms of methods they allow
STAR fails both of them, "badly".
STAR is obviously garbage and a strategy farce, as I'll explain later on EM.
I look forward to seeing it. As I say, I'm not a fan of STAR, but I am still interested in seeing how it stands up to scrutiny given that it has a following. (Actually I'm not aware of how STAR fails monotonicity. I was under the impression that it passed.)
Toby
Toby Pereira wrote:
I'm not a fan of STAR, but I am still interested in seeing how it
stands up to scrutiny given that it has a following. (Actually I'm not
aware of how STAR fails monotonicity. I was under the impression that
it passed.)
Toby,
To give you a bit of a preview before I get around to cooking up all the
examples, nothing with such obvious Push-over incentive can meet
mono-raise (aka "monotonicty")
Suppose X beats Y in the final. Now suppose on some ballots with Y
above X, we raise X so it is now above Y. That could reduce Y's score
enough for it to be replaced in the final
by Z, a candidate that pairwise beats X.
Voters who are mainly concerned to have their favourite X win and are
fairly certain that X will reach the final will have a strong incentive
to give X max points (5) and then also
give a 4 (or even a 5) to all those candidates that they think X can
beat pairwise.
If enough voters use that strategy and it fails, both the finalists
could be candidates with little sincere support.
Chris Benham
On 15/08/2023 9:38 pm, Toby Pereira wrote:
On Tuesday, 15 August 2023 at 06:28:51 BST, C.Benham
cbenham@adam.com.au wrote:
As for what the boxes are about, they are about ensuring that
voting methods have sensible behaviour in certain situations, so I
wouldn't expect them to >>necessarily negatively correlate with a
"good" result.
Then you are not using the right boxes.
I think you probably misread my sentence. I would not expect them to
negatively correlate with a good result. So I probably would expect
passing criteria to correlate positively with a good result. Apologies
for the convoluted sentence.
It's what I just replied to Kristofer - the fact that there's no
way that you can consistently define society's preference in a way
that you can determine whether >>society prefers A or B by looking at
the pairwise comparison.
Then what do you "look at" ??
There's different things you can look at. But what I said is true, not
just my opinion, so it's a question for everyone. But you can still
look at pairwise comparisons and indeed use a Condorcet method. But
I'd want someone to come to this by evaluating various methods and
deciding that this is the best compromise overall, rather than
deciding from the outset that this is the One True Way. I'm not
anti-Condorcet, if this is how it's come across.
I would counter this by saying that it's based on this logical
contradiction.
I'm still not seeing this "logical contradiction".
It's just the premise that if A pairwise beats B then society must
prefer A to B. But it makes no sense to say that society prefers A to
B, B to C and C to A. I don't think this is controversial. It's a
centuries-old realisation.
I would also counter it by saying that someone could equally say (perhaps have a greater
claim) that a method cannot be democratic if it fails participation
I don't see that either. So which method that meets Participation do
you like?
I do actually like both score and approval. I like their simplicity
and the fact that a complete numerical results list can be published
that's simple and easy to understand. And I like the fact that there's
no hidden weird paradoxes in either method. Any criterion they fail is
pretty obvious.
My absolute favourite method isn't suitable for many elections because
it has to be done online, but would be suitable for votes in online
communities etc. It's approval voting but where the current scores are
visible and where a voter can change their vote as much as they like
until the deadline. But because co-ordinated factions might try to
mess with this by voting or changing their vote at the last minute, I
think a non-deterministic end point might be necessary. So you might
have a week of voting plus and end section that has a half life of one
hour. There may be a sense in which this fails participation though
because with perfect game theoretical voting it should become
Condorcet. However, this is likely to be from other voters' reactions
to your presence in the voting procedure rather than you voting
against your own interests. This is a fairly nebulous failure and one
I could easily tolerate for a clean results table and a transparent
and simple method. Also it might in practice not always elect the
Condorcet winner if the Condorcet winner isn't particularly liked. E.g.
49 voters: A>>C>B
49 voters: B>>C>A
2 voters: C>A>B
C (the Condorcet winner) is unlikely to get off the ground in the
first place in this case.
Two of the main ones I tend to look out for are monotonicity and
independence of clones because they are obviously things we would
want and they don't >>seem to be too restrictive in terms of methods
they allow
STAR fails both of them, "badly".
STAR is obviously garbage and a strategy farce, as I'll explain
later on EM.
I look forward to seeing it. As I say, I'm not a fan of STAR, but I am
still interested in seeing how it stands up to scrutiny given that it
has a following. (Actually I'm not aware of how STAR fails
monotonicity. I was under the impression that it passed.)
Toby
I wouldn't count this as a monotonicity failure because it involves decreasing Y's score as well as increasing X's. Mono-raise may have been defined specifically for ordinal ballots where raising a candidate inevitably pushes others down. Whereas with a rated ballot, I think one would be more likely to define monotonicity criteria in terms of increasing a candidate's score while leaving all others the same.
Toby
On Thursday, 17 August 2023 at 05:43:00 BST, C.Benham <cbenham@adam.com.au> wrote:
Toby Pereira wrote:
I'm not a fan of STAR, but I am still interested in seeing how it stands up to scrutiny given that it has a following. (Actually I'm not aware of how STAR fails monotonicity. I was under the impression that it passed.)
Toby,
To give you a bit of a preview before I get around to cooking up all the examples, nothing with such obvious Push-over incentive can meet mono-raise (aka "monotonicty")
Suppose X beats Y in the final. Now suppose on some ballots with Y above X, we raise X so it is now above Y. That could reduce Y's score enough for it to be replaced in the final
by Z, a candidate that pairwise beats X.
Voters who are mainly concerned to have their favourite X win and are fairly certain that X will reach the final will have a strong incentive to give X max points (5) and then also
give a 4 (or even a 5) to all those candidates that they think X can beat pairwise.
If enough voters use that strategy and it fails, both the finalists could be candidates with little sincere support.
Chris Benham
O
Toby,
I wouldn't count this as a monotonicity failure because it involves
decreasing Y's score as well as increasing X's.
This is like a sophist's technical loophole. Why do we particularly
care about "monotonicity failure"? To avoid some hypothetical mild
embarrassment?
For the sake of marketing bragging rights?
Or because it is related to Push-over strategy incentive/vulnerability?
STAR is much worse in that respect than IRV because there the
strategists are entirely
relying on other voters to both get their favourite into the final two
and to there win the pairwise contest, so if too many of X's supporters
try the strategy it
could backfire.
Whereas with STAR the strategists could be a bit cautious and give the
weak candidate they are trying to promote into the final a score of max.
minus one
while also giving their favourite X max. points.
That way all of X's supporters could use the strategy and it could still
succeed.
The 0-5 score ballot is too restrictive (certainly for STAR) Say, as I
earlier advocated, the voters rank however many candidates they want to
and give an approval cutoff wherever
they want, and we elect the pairwise winner between the two most
approved candidates.
That would be very similar to STAR (0-5 score ballots) but wouldn't it
be better? And also a method that fails mono-raise and Condorcet and
many other criteria
and is obviously terrible?
Chris
On 17/08/2023 9:47 pm, Toby Pereira wrote:
I wouldn't count this as a monotonicity failure because it involves
decreasing Y's score as well as increasing X's. Mono-raise may have
been defined specifically for ordinal ballots where raising a
candidate inevitably pushes others down. Whereas with a rated ballot,
I think one would be more likely to define monotonicity criteria in
terms of increasing a candidate's score while leaving all others the same.
Toby
On Thursday, 17 August 2023 at 05:43:00 BST, C.Benham
cbenham@adam.com.au wrote:
Toby Pereira wrote:
I'm not a fan of STAR, but I am still interested in seeing how it
stands up to scrutiny given that it has a following. (Actually I'm
not aware of how STAR fails monotonicity. I was under the impression
that it passed.)
Toby,
To give you a bit of a preview before I get around to cooking up all
the examples, nothing with such obvious Push-over incentive can meet
mono-raise (aka "monotonicty")
Suppose X beats Y in the final. Now suppose on some ballots with Y
above X, we raise X so it is now above Y. That could reduce Y's score
enough for it to be replaced in the final
by Z, a candidate that pairwise beats X.
Voters who are mainly concerned to have their favourite X win and are
fairly certain that X will reach the final will have a strong
incentive to give X max points (5) and then also
give a 4 (or even a 5) to all those candidates that they think X can
beat pairwise.
If enough voters use that strategy and it fails, both the finalists
could be candidates with little sincere support.
Chris Benham
O
On 8/19/23 05:10, C.Benham wrote:
Toby,
I wouldn't count this as a monotonicity failure because it involves
decreasing Y's score as well as increasing X's.
This is like a sophist's technical loophole. Why do we particularly
care about "monotonicity failure"? To avoid some hypothetical mild
embarrassment?
For the sake of marketing bragging rights?
Or because it is related to Push-over strategy
incentive/vulnerability? STAR is much worse in that respect than IRV
because there the strategists are entirely relying on other voters to
both get their favourite into the final two and to there win the
pairwise contest, so if too many of X's supporters try the strategy
it could backfire.
I'd say there are two problems when a method shows nonmonotonicity. The
first is pushover incentive, and the second is that the method somehow
is contradicting its own judgement, which makes that judgement suspect.
Since no method can be consistent in every way possible, it's not
possible for its judgement to be free of flaws in the second sense. But
as we have monotone methods, it seems this particular flaw can be
avoided. (Well, unless we want both LNHs and mutual majority.)
As an example, consider my Methd X of earlier. My simulations seem to
indicate that it has no pushover incentive at all, i.e. if A won, it's
impossible for B>A voters to make B win by upranking A or downranking B.
However, it still has a problem where B>A voters upranking A can change
the winner from A to C. If monotonicity were all about pushover
resistance, I'd be celebrating now and say the thing I've been trying to
solve for years is done. But it's still not entirely monotone.
Or Rob Richie has responded to objections that IRV is non-monotone with
"but you need too much knowledge of the election to pull off pushover,
so it's not a problem". But it's still not monotone.
-km
Chris
It's not that I disagree with your views of STAR's behaviour as a method. And there are changes that could be made that would improve STAR, as you say. However, I just don't think that STAR's failure here can reasonably be called a monotonicity failure.
Toby
On Saturday, 19 August 2023 at 04:10:32 BST, C.Benham cbenham@adam.com.au wrote:
Toby,
I wouldn't count this as a monotonicity failure because it involves decreasing Y's score as well as increasing X's.
This is like a sophist's technical loophole. Why do we particularly care about "monotonicity failure"? To avoid some hypothetical mild embarrassment?
For the sake of marketing bragging rights?
Or because it is related to Push-over strategy incentive/vulnerability? STAR is much worse in that respect than IRV because there the strategists are entirely
relying on other voters to both get their favourite into the final two and to there win the pairwise contest, so if too many of X's supporters try the strategy it
could backfire.
Whereas with STAR the strategists could be a bit cautious and give the weak candidate they are trying to promote into the final a score of max. minus one
while also giving their favourite X max. points.
That way all of X's supporters could use the strategy and it could still succeed.
The 0-5 score ballot is too restrictive (certainly for STAR) Say, as I earlier advocated, the voters rank however many candidates they want to and give an approval cutoff wherever
they want, and we elect the pairwise winner between the two most approved candidates.
That would be very similar to STAR (0-5 score ballots) but wouldn't it be better? And also a method that fails mono-raise and Condorcet and many other criteria
and is obviously terrible?
Chris
On 17/08/2023 9:47 pm, Toby Pereira wrote:
I wouldn't count this as a monotonicity failure because it involves decreasing Y's score as well as increasing X's. Mono-raise may have been defined specifically for ordinal ballots where raising a candidate inevitably pushes others down. Whereas with a rated ballot, I think one would be more likely to define monotonicity criteria in terms of increasing a candidate's score while leaving all others the same.
Toby
On Thursday, 17 August 2023 at 05:43:00 BST, C.Benham <cbenham@adam.com.au> wrote:
Toby Pereira wrote:
I'm not a fan of STAR, but I am still interested in seeing how it stands up to scrutiny given that it has a following. (Actually I'm not aware of how STAR fails monotonicity. I was under the impression that it passed.)
Toby,
To give you a bit of a preview before I get around to cooking up all the examples, nothing with such obvious Push-over incentive can meet mono-raise (aka "monotonicty")
Suppose X beats Y in the final. Now suppose on some ballots with Y above X, we raise X so it is now above Y. That could reduce Y's score enough for it to be replaced in the final
by Z, a candidate that pairwise beats X.
Voters who are mainly concerned to have their favourite X win and are fairly certain that X will reach the final will have a strong incentive to give X max points (5) and then also
give a 4 (or even a 5) to all those candidates that they think X can beat pairwise.
If enough voters use that strategy and it fails, both the finalists could be candidates with little sincere support.
Chris Benham
O
Also a run-off between the most two approved candidates still has STAR's clone problem. If the most approved candidate is cloned, the run-off becomes irrelevant.
Toby
On Saturday, 19 August 2023 at 17:43:12 BST, Toby Pereira tdp201b@yahoo.co.uk wrote:
Chris
It's not that I disagree with your views of STAR's behaviour as a method. And there are changes that could be made that would improve STAR, as you say. However, I just don't think that STAR's failure here can reasonably be called a monotonicity failure.
Toby
On Saturday, 19 August 2023 at 04:10:32 BST, C.Benham cbenham@adam.com.au wrote:
Toby,
I wouldn't count this as a monotonicity failure because it involves decreasing Y's score as well as increasing X's.
This is like a sophist's technical loophole. Why do we particularly care about "monotonicity failure"? To avoid some hypothetical mild embarrassment?
For the sake of marketing bragging rights?
Or because it is related to Push-over strategy incentive/vulnerability? STAR is much worse in that respect than IRV because there the strategists are entirely
relying on other voters to both get their favourite into the final two and to there win the pairwise contest, so if too many of X's supporters try the strategy it
could backfire.
Whereas with STAR the strategists could be a bit cautious and give the weak candidate they are trying to promote into the final a score of max. minus one
while also giving their favourite X max. points.
That way all of X's supporters could use the strategy and it could still succeed.
The 0-5 score ballot is too restrictive (certainly for STAR) Say, as I earlier advocated, the voters rank however many candidates they want to and give an approval cutoff wherever
they want, and we elect the pairwise winner between the two most approved candidates.
That would be very similar to STAR (0-5 score ballots) but wouldn't it be better? And also a method that fails mono-raise and Condorcet and many other criteria
and is obviously terrible?
Chris
On 17/08/2023 9:47 pm, Toby Pereira wrote:
I wouldn't count this as a monotonicity failure because it involves decreasing Y's score as well as increasing X's. Mono-raise may have been defined specifically for ordinal ballots where raising a candidate inevitably pushes others down. Whereas with a rated ballot, I think one would be more likely to define monotonicity criteria in terms of increasing a candidate's score while leaving all others the same.
Toby
On Thursday, 17 August 2023 at 05:43:00 BST, C.Benham <cbenham@adam.com.au> wrote:
Toby Pereira wrote:
I'm not a fan of STAR, but I am still interested in seeing how it stands up to scrutiny given that it has a following. (Actually I'm not aware of how STAR fails monotonicity. I was under the impression that it passed.)
Toby,
To give you a bit of a preview before I get around to cooking up all the examples, nothing with such obvious Push-over incentive can meet mono-raise (aka "monotonicty")
Suppose X beats Y in the final. Now suppose on some ballots with Y above X, we raise X so it is now above Y. That could reduce Y's score enough for it to be replaced in the final
by Z, a candidate that pairwise beats X.
Voters who are mainly concerned to have their favourite X win and are fairly certain that X will reach the final will have a strong incentive to give X max points (5) and then also
give a 4 (or even a 5) to all those candidates that they think X can beat pairwise.
If enough voters use that strategy and it fails, both the finalists could be candidates with little sincere support.
Chris Benham
O
Toby,
Also a run-off between the most two approved candidates still has
STAR's clone problem.
Some years ago I suggested that 2-round Top-Two Runoff could be
improved by using approval ballots in the first round
and then having a runoff between the most approved candidate (the AW)
and the candidate with the most approval opposition
to the AW (i.e. is most approved on ballots that don't approve the AW).
If the most approved candidate is cloned, the run-off becomes irrelevant.
Spoken like someone who lives in parliamentist country. "Clones" aren't
necessarily identical. There could be slight political differences
or one may be less corrupt, or one could just have a much better haircut.
Parties being having incentive to each field two candidates (even if
they are "clones") is maybe not too bad. But STAR uses score ballots
so there is a danger that there being two candidates from the same party
might cause voters to not give both of them max score enough
to stop both of them from making the final.
However, I just don't think that STAR's failure here can reasonably be
called a monotonicity failure.
I think it is very much like one and it's claiming of bragging rights on
that point over IRV is unfair and misleading.
Chris
On 20/08/2023 5:55 am, Toby Pereira wrote:
Also a run-off between the most two approved candidates still has
STAR's clone problem. If the most approved candidate is cloned, the
run-off becomes irrelevant.
Toby
On Saturday, 19 August 2023 at 17:43:12 BST, Toby Pereira
tdp201b@yahoo.co.uk wrote:
Chris
It's not that I disagree with your views of STAR's behaviour as a
method. And there are changes that could be made that would improve
STAR, as you say. However, I just don't think that STAR's failure here
can reasonably be called a monotonicity failure.
Toby
On Saturday, 19 August 2023 at 04:10:32 BST, C.Benham
cbenham@adam.com.au wrote:
Toby,
I wouldn't count this as a monotonicity failure because it involves
decreasing Y's score as well as increasing X's.
This is like a sophist's technical loophole. Why do we particularly
care about "monotonicity failure"? To avoid some hypothetical mild
embarrassment?
For the sake of marketing bragging rights?
Or because it is related to Push-over strategy
incentive/vulnerability? STAR is much worse in that respect than IRV
because there the strategists are entirely
relying on other voters to both get their favourite into the final two
and to there win the pairwise contest, so if too many of X's
supporters try the strategy it
could backfire.
Whereas with STAR the strategists could be a bit cautious and give the
weak candidate they are trying to promote into the final a score of
max. minus one
while also giving their favourite X max. points.
That way all of X's supporters could use the strategy and it could
still succeed.
The 0-5 score ballot is too restrictive (certainly for STAR) Say, as
I earlier advocated, the voters rank however many candidates they want
to and give an approval cutoff wherever
they want, and we elect the pairwise winner between the two most
approved candidates.
That would be very similar to STAR (0-5 score ballots) but wouldn't it
be better? And also a method that fails mono-raise and Condorcet and
many other criteria
and is obviously terrible?
Chris
On 17/08/2023 9:47 pm, Toby Pereira wrote:
I wouldn't count this as a monotonicity failure because it involves
decreasing Y's score as well as increasing X's. Mono-raise may have
been defined specifically for ordinal ballots where raising a
candidate inevitably pushes others down. Whereas with a rated ballot,
I think one would be more likely to define monotonicity criteria in
terms of increasing a candidate's score while leaving all others the same.
Toby
On Thursday, 17 August 2023 at 05:43:00 BST, C.Benham
cbenham@adam.com.au mailto:cbenham@adam.com.au wrote:
Toby Pereira wrote:
I'm not a fan of STAR, but I am still interested in seeing how it
stands up to scrutiny given that it has a following. (Actually I'm
not aware of how STAR fails monotonicity. I was under the impression
that it passed.)
Toby,
To give you a bit of a preview before I get around to cooking up all
the examples, nothing with such obvious Push-over incentive can meet
mono-raise (aka "monotonicty")
Suppose X beats Y in the final. Now suppose on some ballots with Y
above X, we raise X so it is now above Y. That could reduce Y's score
enough for it to be replaced in the final
by Z, a candidate that pairwise beats X.
Voters who are mainly concerned to have their favourite X win and are
fairly certain that X will reach the final will have a strong
incentive to give X max points (5) and then also
give a 4 (or even a 5) to all those candidates that they think X can
beat pairwise.
If enough voters use that strategy and it fails, both the finalists
could be candidates with little sincere support.
Chris Benham
O
Chris
I thought one of your big problems with STAR was the cloning thing. So the fact that score ballots might jeopardise the clone run-off would be a good thing wouldn't it?
Your approval opposition run-off is perhaps similar in outlook to what I suggested previously about using a sequential proportional method to elect two candidates to the run-off. Except that I would deal with clones by allowing a single candidate (or their exact clone depending on how you want to define it) to win both seats in the run-off. In the case where single candidate has so much support that they could win the first two seats in a proportional election, it would be deemed that no run-off is needed.
Toby
On Monday, 21 August 2023 at 13:38:45 BST, C.Benham cbenham@adam.com.au wrote:
Toby,
Also a run-off between the most two approved candidates still has STAR's clone problem.
Some years ago I suggested that 2-round Top-Two Runoff could be improved by using approval ballots in the first round
and then having a runoff between the most approved candidate (the AW) and the candidate with the most approval opposition
to the AW (i.e. is most approved on ballots that don't approve the AW).
If the most approved candidate is cloned, the run-off becomes irrelevant.
Spoken like someone who lives in parliamentist country. "Clones" aren't necessarily identical. There could be slight political differences
or one may be less corrupt, or one could just have a much better haircut.
Parties being having incentive to each field two candidates (even if they are "clones") is maybe not too bad. But STAR uses score ballots
so there is a danger that there being two candidates from the same party might cause voters to not give both of them max score enough
to stop both of them from making the final.
However, I just don't think that STAR's failure here can reasonably be called a monotonicity failure.
I think it is very much like one and it's claiming of bragging rights on that point over IRV is unfair and misleading.
Chris