[EM] Approval vs. IRV

[C.Benham]

Juho Laatu wrote (29 Nov 2011):

We may compare IRV also to the other commonly used single-winner 
method TTR. To be brief, one could say that IRV is better than TTR 
since it has more elimination rounds. IRV's problem in this comparison 
is that it collects so much information that one can, after the 
election, see what strategies would have paid off. In TTR one may have 
very similar problems but people stay happier since they can not see 
the problems. They can't see for example what would have happened if 
some other pair of candidates would have made it to the second round. 
Spoilers may exist but they remain undetected, or at least unverified.



Yes, IRV is much better than TTR partly for that reason. IRV simulates 
"everyone gets one vote each, eliminate one candidate, repeat until one 
remains"  (a process I think is called the Exhaustive Ballot)
except that voters can't sit out a round or two and then come back in, 
and they have to keep voting consistent with their ranking that they 
give at the beginning (so if in the first round they vote for X they

have to keep voting for X until X is eliminated or wins).

This last feature is a big positive because it makes using the devious 
Push-over strategy much more difficult and risky. In TTR if you are 
confidant that your favourite F will make the second round
without your vote (but not make the majority threshold even with your 
vote) you might be able to improve F's chance of winning by voting in 
the first round for a "turkey" T that you are sure that F

can pairwise beat with your vote.

In IRV if you try that and you succeed in causing the final (virtual) 
runoff to be between F and T, F has to win with you still voting for T.


I'd like to add that IRV is an algorithm for those that want to favour 
the large parties. 



The main thing that favours large parties is legislators elected in 
single-member districts versus some form of  PR in multi-member 
districts. But yes, IRV is a bit biased towards slightly off-centre
candidates whereas Approval has a strong bias toward centrist 
candidates.  In Approval it is just possible to have a surprise centrist 
winner, by getting all the approvals of voters in the centre
(with maybe some being exclusive approvals) and approvals from some of 
the wing voters who fear the opposing wing candidate more than they like 
(or are hopeful about) their own.



Chris Benham

Election-Methods mailing list - see http://electorama.com/em for list info

Re: [EM] ... wrt Burlington et al.

[robert bristow-johnson]

again, the subject is not about me and the header should reflect that.


On 11/27/11 4:15 PM, David L Wetzell wrote:



dlw:   The two major-party equilibrium would be centered
around the
   de facto center.


KM:   But positioning yourself around the de facto center is
dangerous
   in IRV. You might get center-squeezed unless either you or your
   voters start using strategic lesser-evil logic - the same
sort of
   logic that IRV was supposed to free you from by "being
impervious
   to spoilers".

dlw: the cost of campaigning in "less local" elections is high
enuf that it's hard for a major party to get center-squeezed.
 And if such did happen, they could reposition to prevent it.


RBJ:the counterexample, again, is Burlington Vermont.  Dems
haven't sat in the mayor's chair for decades.


dlw: Not sure this is a relevant counter example.  With IRV, the two 
major parties would become the Progs and the Dems who would be 
centered around the de facto center of Burlington.

where is this de facto center?  around the Progs?  or the GOP?


RBF:


who's that?


the counterexample, again, is Burlington Vermont.  Dems haven't sat in
> the mayor's chair for decades.

MW: Is this due to a split of the liberal vote by progressives or
other
liberal blocs? Or is it due to a truly Republican leaning demographic?


dlw: More to the point, this is not an arg against IRV since it was 
only tried for one election in Burlington.


no, we used it in 2006 and 2009.  in 2006, the IRV winner, Plurality 
winner, and Condorcet winner were one and the same person.


dlw: I would not describe IRV as introducing unstable weirdness.  It 
maintains a two-party dominated system and facilitates that those two 
major parties tend to position themselves around the de facto 
(shifting) center.


the three parties do *not* shift to position themselves around any 
shifting center.  it's much more complicated than that.



MW:Is this due to a split of the liberal vote by progressives or other

liberal blocs? Or is it due to a truly Republican leaning
demographic?

RBS:


who's that?


Burlington is, for the U.S., a very very liberal town with a
well-educated and activist populace.  it's the origin of Ben &
Jerry's and now these two guys are starting a movement (
http://movetoamend.org/ ) to get a constitutional amendment to
reverse the obscene Citizens United ruling of the Supreme Court.

the far north end of Burlington (called the "New North End", also
where i live) is a little more suburban in appearance and here is
where the GOP hangs in this town.

the mayors have been Progs with an occasional GOP.  it is
precisely the "center squeeze" syndrome and IRV didn't solve that
problem. and without getting Condorcet adopted, i am not sure how
it will be reversed.


dlw: If you had given IRV another election, it would have likely 
solved the problem.


what problem do you mean (that is likely solved)?

You cannot seriously think that one Burlington has driven a stake in 
the heart of IRV for once and forever.




it has for Burlington, and likely for the rest of the state (there was 
even a bill passed, but vetoed by the previous governor to use IRV for 
the guv's election, that's where i would argue that precinct summability 
would become a salient problem).





RBS:





but the only voting methods folks generally see here are FPTP,
FPTP with a delayed runoff, and IRV.  and, thanks to FairVote,
nearly everyone are ignorant of other methods to tabulate the
ranked ballot than the STV method in IRV.


dlw: And it was hard work to get people to get IRV..., just think how 
hard it would be to teach them about 4 very heterogeneous election rules.


IRV, with its kabuki dance of transferred votes, is more complicated 
than Condorcet.  when i was asked by one of the leaders in this town of 
the anti-IRV movement to explain Condorcet simply (since that was most 
of their case against IRV - most of their signs said "Keep Voting 
Simple"), i answered "If more voters agree that Candidate A is a better 
choice for office than Candidate B, then Candidate B is not elected."  
pretty simple and hard to argue with.


often the discussion here and that regarding Approval eventually 
discusses how voters can adapt their voting strategy to the method that 
is advocated for, and i continue to say that this misses the point.  the 
voters shouldn't have to be burdened with any need to strategize at 
all.  and they shouldn't be punished for failing to strategize.


while it is true that Condorcet may tend to favor the centrist (whereas 
IRV favors the largest subgroup in the largest group, e.g. in Burlington 
IRV favored the largest group, the Liberals, and of the Liberals, it 
favored the Progs over the Dems, because there wa

Re: [EM] Approval vs. IRV (hopefully tidier re-send)

[Ted Stern]

On 28 Nov 2011 20:24:37 -0800, Chris Benham wrote:
>
> Matt Welland wrote (26 Nov 2011):
>
> Also, do folks generally see approval as better than or worse than IRV?
>
> To me Approval seems to solve the spoiler problem without introducing
> any unstable weirdness and it is much simpler and cheaper to do than
> IRV.
>
> If we are talking about the classic version of IRV known as the
> "Alternative Vote" in the UK and "Optional Preferential Voting" in
> Australia, then I see IRV on balance as being better than Approval.
>
> The version of IRV I'm referring to:
>
> *Voters strictly rank from the top however many or few candidates
> they wish.  Until one candidate remains, one-at-a time eliminate
> eliminate the candidate that (among remaining candidates) is
> highest-ranked on the fewest ballots.*
>
> The "unstable weirdness" of Approval is in the strategy games among
> the rival factions of voters, rather than anything visible in the
> method's algorithm.
>
> Approval is more vulnerable to disinformation campaigns. Suppose
> that those with plenty of money and control of the mass media know
> from their polling that the likely outcome of an upcoming election
> is A 52%, B 48% and they much prefer B.
>
> In Approval they can sponsor and promote a third candidate C, one
> that the A supporters find much worse than B, and then publish false
> polls that give C some real chance of winning. If they can
> frighten/bluff some of A's supporters into approving B (as well as
> A) their strategy can succeed.
>
> 47: A
> 05: AB (sincere is A>B)
> 41: B
> 07: BC
>
> Approvals: B53,   A52,  C7

I find this example contrived.

 * If mass polling is available, many people will be aware of the
   52/48 split between A and B ahead of time.

 * Corruption is a separate issue.  With proper election funding
   control, support for C would be restricted.

> Approval is certainly the "bang for buck" champion, and voters never
> have any incentive to vote their sincere favourites below
> equal-top. But to me the ballots are insufficiently expressive by
> comparison with the strict ranking ballots used by IRV.

I agree.

Approval-Bucklin (AKA ER-Bucklin) has the advantage in your contrived
example of allowing the A > B voters to add B at a lower rank, which
would not count unless neither A nor B achieves a majority.

In many cases, it would not be necessary to rate candidates at the
second (or lower) choice option, but having that option increases the
available nuance of the vote.

> IRV has some Compromise incentive, but it is vastly less than in
> FPP.  Supposing we assume that there are 3 candidates and that you
> the voter want (maybe for some emotional or long-term reason) to
> vote your sincere favourite F top even if you think (or "know") that
> F can't win provided you don't thereby pay too high a strategic
> penalty, i.e. that the chance is small that by doing that you will
> lose some (from your perspective positive) effect you might
> otherwise have had on the result.

However IRV does impose a false choice -- that you must rank your
preferences separately, no equal ranks allowed.

> In FPP, to be persuaded to Compromise (i.e.vote for your compromise
> "might win" candidate C instead of your sincere favourite F) you
> only have to be convinced that F won't be one of the top two
> first-preference place getters.
>
> In IRV if you are convinced of that you have no compelling reason to
> compromise because you can expect F to be eliminated and your vote
> transferred to C. No, to have a good reason to compromise you must
> be convinced that F *will* be one of the top 2 (thanks to your vote)
> displacing C, but will nonetheless lose when C would have won if
> you'd top-voted C.
>
> In my opinion IRV is one of the reasonable algorithms to use with
> ranked ballots, and the best for those who prefer things like
> Later-no-Harm and Invulnerability to Burial to either the Condorcet
> or FBC criteria.

But are these the criteria we really want to achieve in a
single-winner election?  To say that LNH is the most important
criterion is, at its most basic level, an emotional argument.  While
effective in persuading the electorate, I think what we really want to
look for is a method that does a good job of finding the candidate
closest to the center of the electorate, while resisting strategic
manipulation.

Ted
-- 
araucaria dot araucana at gmail dot com


Election-Methods mailing list - see http://electorama.com/em for list info

Re: [EM] Simplest paper count to produce a winner in the smith set.

[Jameson Quinn]

You can eliminate all candidates that have less than half the top approval
score, immediately. Australia is a bad example because they require full
ranking; but without that requirement, you could expect that each
candidate's approval total will be something on the order of min(50%,
2xFirst choices). Using the numbers you gave, that would mean only 3
parties left after elimination.

Jameson

2011/11/29 Clinton Mead 

>
>
> On Wed, Nov 30, 2011 at 2:47 AM, Kristofer Munsterhjelm <
> km_el...@lavabit.com> wrote:
>
>> Clinton Mead wrote:
>>
>>> What would be the simplest paper count that will produce a winner in the
>>> smith set?
>>
>>
>> Then while there is more than one candidate left, eliminate the pairwise
>> loser of the two remaining candidates with the least approval score.
>>
>>
> I was thinking the a similar thing, but then I looked at typical election
> first preference counts, which are often like the following like the
> following (at least in Australia).
>
> Major Party 1: 41%
> Major Party 2: 39%
> Minor Party 1: 10%
> Minor Party 2: 3%
> Minor Party 3: 2%
> Minor Party 4: 2%
> Minor Party 5: 2%
> Minor Party 6: 1%
>
> Producing this entails one pass through the ballot (100% of papers need to
> be examined for one preference). This is the base line for FPP.
>
> For IRV, we can eliminate the 6 minor candidates in bulk, because they sum
> to less than the vote of the second candidate. So then we reexamine the 6
> minor party candidates for preferences. This means we have to look at 20%
> more votes.
>
> Our total work of IRV: 120% of FPP.
>
> For the method you suggest (with the minor difference that I'll use first
> preference to initially rank ballots) we need 100% work to do the first
> count, then, with Minor Party 6 and Minor Party 5 on a total of 3%, we need
> to look at the other 97% of ballots to do a pairwise comparison. Then we
> eliminate the pairwise loser, then we have to look at 95% of the remaining
> ballots to compare Minor 5/6 with Minor 4, etc.
>
> We get a result which might involve 400-500% more looks at ballot papers
> than FPP.
>
> The method I suggest is slightly different in that it starts from the top.
> We compare the top two candidates pairwise, this involves looking at 100%
> of the votes to do the first preference count, and an additional 20% to do
> the two candidate count. We're now at 120% of the work of FPP (one could
> say you could do the first preference and two candidate in the same pass,
> but this doesn't significantly lower the work, the time consuming work is
> looking for preferences, not flicking through ballot papers).
>
> Now, lets say Major Party 2 beats Major Party 1 pairwise. Then we
> distribute Major Party 1's preferences. This takes looking at 41% of the
> votes.
>
> Now we're at 161%.
>
> If Major Party 2 now has a majority, we have a winner. But if it doesn't,
> we pairwise compare Major Party 2 with Minor Party 1.
>
> This involves looking at all of the other minors vote, which is 10%. If
> Major Party 2 beats Minor Party 1, it probably has a majority, if it
> doesn't, it's very close, and will quickly get a majority as it defeats
> other minor candidates pairwise and distributes their preferences.
>
> If Minor Party 1 beats Major Party 2 however, then we need to distribute
> Major Party 2's preferences,  which involves looking at another 39-50% of
> the ballots.
>
> At this point, it is likely Minor Party 1 has a majority (particularly
> considering Major 1 and Major 2 are eliminated). If this is the case, we
> then just need to check Minor Party 1 v Major Party 1 pairwise. This
> involves looking at the 49% of votes which are not theirs. If Minor Party 1
> pairwise beats Major Party 1, it is the winner, if Major Party 1 beats
> Minor Party 1, we have a cycle (Major Party 1 < Major Party 2 < Minor Party
> 1 < Major Party 1) and we resolve this in favour of the first preference
> winner.
>
> The idea of this method is that it typically takes only 160% or so of the
> work of a FPP, and in the worse (typical) case perhaps 250% or at most 300%
> of the work of a FPP count. In particular, it's not particularly burdensome
> compared to IRV, which in the best case is around 120% and in the worse
> case around 200%.
>
> 
> Election-Methods mailing list - see http://electorama.com/em for list info
>
>

Election-Methods mailing list - see http://electorama.com/em for list info

Re: [EM] Jameson: MMT, MTAOC, MJ

[Jameson Quinn]

I honestly don't understand your hostility to me. Can you explain it?

2011/11/29 MIKE OSSIPOFF 

>
> Jameson--
>
> You had said:
>
> Majority
>  Judgment has similar advantages to MTA in this case.
>
> [endquote]
>
> I asked:
>
> Does it? Who knows?
>
> You replied:
>
> Anyone who takes the time to read the academic 
> literature
> .
>
> [endquote]
>
> Translation: You yourself don't know the answer.
>
> MJ's advocates are peculiarly reticent about its specific properties,
> advantages and criterion-compliances.
>
> Alright, I'll answer it for you. MJ does not have advantages similiar to
> those of MTA.
>
>
>
> Have its proponents told what criteria it meets and specifically what
> guarantees it
> offers?
>
> How does it do in the Approval bad-example?
>
>
> You answered:
>
> Same as MTA.
>
> [endquote]
>
> Ok, in other words, MJ doesn't pass in the ABE. Thank you.
>
> You continued:
>
> That is, honest-votes will reliably give a good result, unlike unstable
> Approval; but strategic voting will lead to failure.
>
> [endquote]
>
> Nonsense. That's a remarkably naive statement. In every nonprobabilistic
> method, strategy is advantageous.
>

Sorry, you misunderstood me. I meant that strategic voting would be
advantageous for the voters, and thus would lead to the method failing the
ABE/Chicken Dilemma.

>
> So you think that you've found one for which that isn't so?  :-)
>

No. Actually, it seems to me that you think I'm an idiot and/or an enemy of
yours and so you interpret everything I say in the most uncharitable
possible way. I hope I'm wrong about that impression, because I am neither
of those things.

>
>
>
>
> (to compare it to MTAOC)
>
>
> If you're unwilling to research the published answers to your own
> questions, why do you persist in asking us to look up your alphabet soup in
> old posts? For instance, I know what you mean by MTAOC (a system with a
> strong dishonest-fill incentive
>
> [endquote]
>
> In MTAOC, your middle rating of a lesser-evil (B) can't help the
> lesser-evil beat your favorite (A). And the B-favorite voters reciprocate
> that middle rating, then it's more likely that one or the
> other of those 2 candidates will win, instead of someone (C) less-liked by
> both factions. If it looks as if that would elect A, then the B voters
> don't benefit from middle-rating A
> unless they sincerely prefer A to C.  Likewise if A and B are reversed in
> that sentence.
>

All that is true. And has nothing to do with the problem I pointed out. The
method has a strong dishonest-fill incentive. A Gore>Bush>Nader voter could
in some circumstances elect Gore only by strategically voting Gore>Nader;
but if Nader had slightly higher-than-expected support, then that dishonest
strategy could lead Nader to win even with as little as 25% honest support.

>
> You continued:
>
> , but searching past messages for that acronym just gives the written-out
> name
>
> [endquote]
>
> No, each method's definition was announced in a post whose subject line
> contained the name of that method, written out,
> and, in nearly every case, with the abbreviation in parentheses.
>
> False.

>
>
> What majority-rule guarantees does it offer? Does it meet 3P or 1CM?
>
>
> You replied:
>
> It meets 3P, which I happen to remember what it means.
>
> [endquote]
>
> The 3P complying methods that I'm aware of all make two special
> distinctions, usually a distinction between top rating vs rating below top;
> and between rating vs not
> rating. MJ makes no such distinctions. So, if it meets 3P, then what are
> the two protection-levels required for 3P compliance?
>

Yes it does. Every single rating level in MJ is a "protection level" for
3-level-protection.


>
> You continued:
>
> If you define 1CM  I'll tell you if
> it meets that.
>
> [endquote]
>
> Oh, that's ok. _I'll_ tell _you_:  It doesn't. For the reasons stated in
> my paragraph above.
>

You just told me nothing more than if I told you that it meets QWERT or
that it doesn't meet ZXCVB. I suspect that your 1CM is actually a
pernicious criterion that it's better not to pass, but since you prefer to
make unreliable assertions about what methods pass it than actually
re-posting or linking the definition, I'm not going to bother checking.


>
> As I said, I've been meaning to post my definitions in the wikipedia.
> Lately I haven't had a lot of time for computer. But I'm soon
> going to post those definitions.
>
> Ok, it doesn't pass in the ABE, and it doesn't pass 3P or 1CM. Well, if we
> defined a 2P (as compared to 3P), it would pass that, as would Approval
> and RV. Maybe there should be a 2P criterion. It probably passes WDSC too,
> and probably FBC.
>
>
>
> It probably has a strategy situation very much like that of ordinary RV.
> The method of summed scores.
>
>
> You replied:
>
> No. For most voters in real-world studies of MJ, their honest,
> not-even-normalized MJ bal

[EM] Small omission in MTAOC program

[MIKE OSSIPOFF]

In the last of the three program sections, there should be one thing added to 
the instructions in
the if-statement:

recalculate par(x,y)

Mike Ossipoff

  
Election-Methods mailing list - see http://electorama.com/em for list info

[EM] Approval vs IRV

[MIKE OSSIPOFF]

To say that IRV fails FBC is an understatement.

IRV fails FBC with a vengeance.

IRV thereby makes a joke any election in which it is used.

As I've already said, all it takes is for favoriteness-support to taper 
moderately gradually away from the middle, something
that is hardly unusual. Eliminations from the extremes will send transfers 
inward to feed the candidates flanking a middle CW,
resulting in hir elimination.

If you think that you likely need a compromise to beat someone worse, then you 
had better vote hir in 1st place, burying
your favorite, lest your favorite eliminate your compromise and then lose to 
someone worse than the compromise.

This would be observed in a quite high percentage of IRV elections if the 
relevant information were disclosed in the
election results report.

And the attempts of IRVists to evade or excuse its precinct-non-countability 
testify only to their determination to try to defend IRV regardless
of what contortions that defense requires.

And no, I don't claim that all of the methods that I like and propose are 
precinct-countable. But precinct-countability remains
a significant advantage of Approval over IRV.

If I propose a method that isn't precinct countable, then I had better show 
some reason why it's very good. 

Mike Ossipoff

  
Election-Methods mailing list - see http://electorama.com/em for list info

Re: [EM] Simplest paper count to produce a winner in the smith set.

[Clinton Mead]

On Wed, Nov 30, 2011 at 2:47 AM, Kristofer Munsterhjelm <
km_el...@lavabit.com> wrote:

> Clinton Mead wrote:
>
>> What would be the simplest paper count that will produce a winner in the
>> smith set?
>
>
> Then while there is more than one candidate left, eliminate the pairwise
> loser of the two remaining candidates with the least approval score.
>
>
I was thinking the a similar thing, but then I looked at typical election
first preference counts, which are often like the following like the
following (at least in Australia).

Major Party 1: 41%
Major Party 2: 39%
Minor Party 1: 10%
Minor Party 2: 3%
Minor Party 3: 2%
Minor Party 4: 2%
Minor Party 5: 2%
Minor Party 6: 1%

Producing this entails one pass through the ballot (100% of papers need to
be examined for one preference). This is the base line for FPP.

For IRV, we can eliminate the 6 minor candidates in bulk, because they sum
to less than the vote of the second candidate. So then we reexamine the 6
minor party candidates for preferences. This means we have to look at 20%
more votes.

Our total work of IRV: 120% of FPP.

For the method you suggest (with the minor difference that I'll use first
preference to initially rank ballots) we need 100% work to do the first
count, then, with Minor Party 6 and Minor Party 5 on a total of 3%, we need
to look at the other 97% of ballots to do a pairwise comparison. Then we
eliminate the pairwise loser, then we have to look at 95% of the remaining
ballots to compare Minor 5/6 with Minor 4, etc.

We get a result which might involve 400-500% more looks at ballot papers
than FPP.

The method I suggest is slightly different in that it starts from the top.
We compare the top two candidates pairwise, this involves looking at 100%
of the votes to do the first preference count, and an additional 20% to do
the two candidate count. We're now at 120% of the work of FPP (one could
say you could do the first preference and two candidate in the same pass,
but this doesn't significantly lower the work, the time consuming work is
looking for preferences, not flicking through ballot papers).

Now, lets say Major Party 2 beats Major Party 1 pairwise. Then we
distribute Major Party 1's preferences. This takes looking at 41% of the
votes.

Now we're at 161%.

If Major Party 2 now has a majority, we have a winner. But if it doesn't,
we pairwise compare Major Party 2 with Minor Party 1.

This involves looking at all of the other minors vote, which is 10%. If
Major Party 2 beats Minor Party 1, it probably has a majority, if it
doesn't, it's very close, and will quickly get a majority as it defeats
other minor candidates pairwise and distributes their preferences.

If Minor Party 1 beats Major Party 2 however, then we need to distribute
Major Party 2's preferences,  which involves looking at another 39-50% of
the ballots.

At this point, it is likely Minor Party 1 has a majority (particularly
considering Major 1 and Major 2 are eliminated). If this is the case, we
then just need to check Minor Party 1 v Major Party 1 pairwise. This
involves looking at the 49% of votes which are not theirs. If Minor Party 1
pairwise beats Major Party 1, it is the winner, if Major Party 1 beats
Minor Party 1, we have a cycle (Major Party 1 < Major Party 2 < Minor Party
1 < Major Party 1) and we resolve this in favour of the first preference
winner.

The idea of this method is that it typically takes only 160% or so of the
work of a FPP, and in the worse (typical) case perhaps 250% or at most 300%
of the work of a FPP count. In particular, it's not particularly burdensome
compared to IRV, which in the best case is around 120% and in the worse
case around 200%.

Election-Methods mailing list - see http://electorama.com/em for list info

[EM] Jameson: MMT, MTAOC, MJ

[MIKE OSSIPOFF]

Jameson--

You had said:


Majority

 Judgment has similar advantages to MTA in this case.



[endquote]



I asked:

Does it? Who knows? 
You replied:

Anyone who takes the time to read the academic literature.

[endquote]

Translation: You yourself don't know the answer. 

MJ's advocates are peculiarly reticent about its specific properties, 
advantages and criterion-compliances.

Alright, I'll answer it for you. MJ does not have advantages similiar to those 
of MTA.

 

Have its proponents told what criteria it meets and specifically what 
guarantees it

offers?



How does it do in the Approval bad-example? 
You answered:

Same
 as MTA. 

[endquote]

Ok, in other words, MJ doesn't pass in the ABE. Thank you.

You continued:

That is, honest-votes will reliably give a good result, unlike 
unstable Approval; but strategic voting will lead to failure.

[endquote]

Nonsense. That's a remarkably naive statement. In every nonprobabilistic 
method, strategy is advantageous.

So you think that you've found one for which that isn't so?  :-)




 (to compare it to MTAOC)



If you're unwilling to research the
 published answers to your own questions, why do you persist in asking 
us to look up your alphabet soup in old posts? For instance, I know what
 you mean by MTAOC (a system with a strong dishonest-fill incentive

[endquote]

In MTAOC, your middle rating of a lesser-evil (B) can't help the lesser-evil 
beat your favorite (A). And the B-favorite voters reciprocate that middle 
rating, then it's more likely that one or the
other of those 2 candidates will win, instead of someone (C) less-liked by both 
factions. If it looks as if that would elect A, then the B voters don't benefit 
from middle-rating A
unless they sincerely prefer A to C.  Likewise if A and B are reversed in that 
sentence.

You continued:

, but searching past 
messages for that acronym just gives the written-out name

[endquote]

No, each method's definition was announced in a post whose subject line 
contained the name of that method, written out,
and, in nearly every case, with the abbreviation in parentheses.



 
What majority-rule guarantees does it offer? Does it meet 3P or 1CM?

You replied:

It meets 3P, which I happen to remember what it means. 

[endquote]

The 3P complying methods that I'm aware of all make two special distinctions, 
usually a distinction between top rating vs rating below top; and between 
rating vs not
rating. MJ makes no such distinctions. So, if it meets 3P, then what are the 
two protection-levels required for 3P compliance?

You continued:

If you define 1CM I'll tell you if it meets that.

[endquote]

Oh, that's ok. _I'll_ tell _you_:  It doesn't. For the reasons stated in my 
paragraph above.

As I said, I've been meaning to post my definitions in the wikipedia. Lately I 
haven't had a lot of time for computer. But I'm soon
going to post those definitions.


 
Ok, it doesn't pass in the ABE, and it doesn't pass 3P or 1CM. Well, if we 
defined a 2P (as compared to 3P), it would pass that, as would Approval
and RV. Maybe there should be a 2P criterion. It probably passes WDSC too, and 
probably FBC. 





It probably has a strategy situation very much like that of ordinary RV. The 
method of summed scores.

You replied:

No.
 For most voters in real-world studies of MJ, their honest, 
not-even-normalized MJ ballot was strategically optimal. That is clearly
 far better than Range. 

[endquote]

Oh, that's different! In MJ, some voters don't have incentive to rate other 
than sincerely :-)   

And the strategizing voters won't affect the outcome?

By the way, if you're going to advocate MJ, it needs a better name. Majority 
Judgement might be ok as a promotional name, but it is not a descriptive name.
How about (the obvious) "Cardinal Median" or "Median Cardinal".

Mike Ossipoff










  
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Re: [EM] Simplest paper count to produce a winner in the smith set.

[Kristofer Munsterhjelm]

Clinton Mead wrote:
What would be the simplest paper count that will produce a winner in the 
smith set?


I'm not completely sure how your method works, but how about this?

Count the number of ballots on which each candidate is ranked (in any 
position). Call each candidate's count his "approval score". Then while 
there is more than one candidate left, eliminate the pairwise loser of 
the two remaining candidates with the least approval score.


Eliminating losers won't turn a ranked candidate into a non-ranked 
candidate (or vice versa), so unlike IRV, you don't have to do a recount 
for every round.


It should also pick a winner from the Smith set. Say all but one of the 
Smith set candidates have been eliminated. Then the remaining Smith set 
candidate will, by definition of the Smith set, beat everybody else 
pairwise, and so nobody will be able to eliminate him. Therefore, that 
remaining Smith set member will be elected. QED.


The counting burden isn't that hard, either: you need one pass to 
calculate the approval scores, and then (n-1) (for n candidates) 
pairwise counts. I don't think you can do better than (n-1) pairwise 
counts and still be sure to elect someone in the Smith set.


You could replace the approval count with a Plurality count to get 
something simpler, but that could also be unfair to Smith set candidates 
that have few first place votes, and it wouldn't be consistent: 
eliminating candidates from a Plurality count would mean other 
candidates could be exposed, and so you'd have to recount as in IRV.



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Re: [EM] new revised ranked pair method in matrix form

[Ross Hyman]

Refinement: Don't determine winner until the end.

C_i is the ith candidate.  Initially M is the Identity matrix of size equal to 
the number of candidates. 

The pairs are ranked in order.  Affirm each group of equally ranked pairs in 
order, from highest to lowest.   To Affirm a group of equally ranked pairs 
create the matrix D where D_ij  = 1 for each C_i >C_j that is to be affirmed at 
this rank.  D_ij=0 otherwise.  Replace the old M matrix with the new one: M + 
MDM.

After all groups have been affirmed, form the matrix W = M - M^T where M^T is 
the transpose of M.

The winner is the C_b such that no W_ab is positive.





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Re: [EM] Approval vs. IRV

[Juho Laatu]

On 29.11.2011, at 6.07, C.Benham wrote:

> In IRV if you are convinced of that you have no compelling reason to 
> compromise because you
> can expect F to be eliminated and your vote transferred to C. No, to have a 
> good reason to compromise
> you must be convinced that F *will* be one of the top 2 (thanks to your vote) 
> displacing C, but will
> nonetheless lose when C would have won if  you'd top-voted C.

I guess F could cause (the otherwise winner) C to be eliminated, and F could be 
eliminated already before F reaches the top 2 position (40: A, 15: C, 25: E>C, 
20: F>C). But anyway, it is less risky to top rank one's favourite in IRV than 
in FPP.

We may compare IRV also to the other commonly used single-winner method TTR. To 
be brief, one could say that IRV is better than TTR since it has more 
elimination rounds. IRV's problem in this comparison is that it collects so 
much information that one can, after the election, see what strategies would 
have paid off. In TTR one may have very similar problems but people stay 
happier since they can not see the problems. They can't see for example what 
would have happened if some other pair of candidates would have made it to the 
second round. Spoilers may exist but they remain undetected, or at least 
unverified.

People seem to be reasonably happy with TTR. The random nature of TTR seems to 
be just part of the competition (rules that are equal to all) in the minds of 
the voters. The elimination based algorithm of IRV may also look pretty natural 
and fair to regular voters. It takes some effort to explain to them that in 
some cases the IRV results might not be ideal. Maybe people don't care that 
much about the complex details.

> In my opinion IRV is one of the reasonable algorithms to use with ranked 
> ballots, and the best for those
> who prefer things like Later-no-Harm and Invulnerability to Burial to either 
> the Condorcet or  FBC
> criteria.

I'd like to add that IRV is an algorithm for those that want to favour the 
large parties. In some environments this might be intentional, and in some a 
problem. I note that also in Condorcet methods voters can trust that betraying 
their favourite or burial are very probably not useful strategies for them, and 
the risk of later preferences causing some harm is small.

If one specifically wants Condorcet winners to win the election, then IRV may 
not the the best choice. With three candidates the centre candidate will be 
eliminated if it has less first preference support than the others. This 
property is related to the (above mentioned) question on whether one wants to 
favour large parties (with lots of first preference support) or not.

Approval is maybe a reasonable algorithm for non-competitive elections where 
two rating values are sufficient.

Juho







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