[EM] Poll for favorite single winner voting system with OpaVote

2011-10-13 Thread MIKE OSSIPOFF

To the person conducting the poll:
 
Are you going to count the rankings to determine a winner? By what method?
 
I suggest that you look for a Condorcet winner, an alternative that isn't 
pairwise-beaten, in any of its pairwise comparisons. And announce it to this 
mailing list.
 
Also, I hope that you'll post, to this list, all the ballots, so that people 
can apply, to them, whatever rank-count method they want to. 
 
I claim that something is missing from the poll: On the ballot, you list 
Condorcet as a method. Condorcet isn't a particular method. Condorcet is a 
family of methods, in which we elect the CW if there is one; and, if there 
isn't one, we elect the candidate whose greatest pairwise defeat is the least.
 
That's Condorcet's method. Of course it leaves open the question of how we 
measure the magnitude of a pairwise defeat.
 
It's widely-agreed now that pairwise opposition, in a pairwise comparison, is 
the best way to measure a pairwise defeat.
 
In other words, if X pairwise-beats Y, measure that defeat by the number of 
people who ranked X over Y. I've called that winning-votes, and I and some 
others have been abbreviating it wv.
 
The wv method that does Condorcet's method most literally is Plain Condorcet. 
It's also the briefly and simply defined Condorcet version, and therefore is 
the one suitable for a public proposal.
 
I defined PCin my previous post to this mailing list. But its definition is so 
brief that I'll  state the definition here:
 
 
Definition of Plain Condorcet (PC):
 
If there is a candidate who doesn't have a pairwise defeat, s/he wins. If more 
than one candidate are without pairwise defeat, then they win.
 
Otherwise, the winner is the candidate whose greatest pairwise defeat is the 
least (as measured by wv).
 
[end of PC definition]
 
 
So, I suggest that, instead of just listing Condorcet, it would be better to 
ask for some nominations of Condorcet versions. I claim that PC is the publicly 
proposable one, though Ranked-Pairs might be briefly-worded anough to be 
proposable too.
 
So then, allow me to nominate two Condorcet versions, to replace Condorcet on 
the ballot:
 
Plain Condorcet
Ranked-Pairs
 
I'd also like to nominate a pairwise-count method that isn't a Condorcet 
version, but is just as good as PC. It may have been proposed by Forest, some 
years ago:
 
MinMaxPairwise-Opposition  (MMPO)
 
Definition of MMPO:
 
The first line is the same as for PC.
 
Otherwise, the winner is the candidate whose greatest pairwise opposition is 
the least. 
 
A pairwise opposition, of X, is the number of people ranking some one 
particular candidate over X. So, X has a pairwise opposition with respect to 
each candidate. So we elect the candidate whose greatest pairwise opposition is 
the least.
 
[end of MMPO definition]
 
I'd previously thought that MMPO is briefer to define clearly than is PC, but 
now I'm not so sure.
 
Anyway, so I nominate the following methods:
 
PC
MMPO
Ranked-Pairs.
 
If those methods were on the ballot (People should be invited to nominate 
methods, and all nominated methods should be on the ballot), I would rank as 
follows:
 
1. PC
2. MMPO
3. Approval
4. Ranked-Pairs
5. Range-Voting (RV)
 
I like the triangular shape of that ranking, which is entirely accidental.
 
It could be argued that Approval is more winnable than the rank methods, 
because there are so many contentiously-divergent proposals for counting 
rankings.  True. But sometimes peope object to Approval, perceiving it as a 
spoiled Plurality ballot. Though it can be explained that Approval is the 0,1 
points system, and amounts to each person casting _one_ vote between some two 
sets of candidates, I feel that people might be more enthusiastic about the 
greater ambitiousness of a rank method. So maybe it's better to offer them a 
really good, but briefly-defined rank method, such as those that I've nominated.
 
That's why I've ranked PC and MMPO over Approval. I've ranked Ranked-Pairs 
below Approval, because its definition might not be as clear to voters asked to 
sign an initiative petition or vote for enactment of a voting system.
 
I've ranked Range-Voting last, among the candidate I rank, because, though it's 
better than the methods I didn't rank, it has a strategy problem that Approval 
doesn't have (when some people vote sincerely and other people strategize). 
Also, it's more difficult to implement than Approval.
 
Now, the question is, to get a winner in the poll, which method do we use, for 
counting the ballots?
 
I suggest Voter's-Choice:
 
In addition to voting a ranking, invite each voter to designate a method for 
counting this election. For that purpose, of course it would be necessary for 
the ballot to allow for Approval balloting and RV balloting.
 
Count the ballots by all of the methods that have been designated by someone.
 
Give each method's winner a point-score equal to the number of people who have 
designated that method.
 
The winner is the 

Re: [EM] [CES #3845] condorcet range voting -- which one yields more condorcet winners?

2011-10-13 Thread Kevin Venzke
Hi Jameson,

--- En date de : Mer 12.10.11, Jameson Quinn jameson.qu...@gmail.com a écrit :




 

Maybe you should do sims first, emit flames second.


That's a fair criticism, and one I continue to violate in this message. I 
wonder if Kevin Venzke has any sims which speak to this question.
 
 
Thanks for remembering me. The question is sincere Condorcet efficiency between 
Range and something like MCA? I have three scenarios on-hand (two 1D, one
spectrumless, all three-candidate) and MCA is a bit better than (four-slot) 
Range in
all three. But it is rare that either method has the efficiency of a Condorcet 
method.
 
My sims use 100% strategic voters and polling by the way.
 
A few comparisons.
Spectrumless (blocs have random preferences):
IRV 92.2% (of trials with a CW)
WV 91.7%
MCA 90.6%
Range 90.3%
Approval 88.4% (note that Range doesn't quite become Approval due to the voters
being divided into a fairly small number of strategizing blocs)
FPP 84.8%
 
1D with random candidate positions:
WV 99.1%
IRV 98.4%
MCA 97.9%
Range 97.6%
Approval 96.5%
FPP 84.0%
 
1D with random candidate positions but distance from center halved 
(center-heavy):

WV 97.8%
IRV 97.3%
MCA 96.9%
Range 95.7%
Approval 93.2%
FPP 76.6%
 
Note that the voters have the ability to get what they want a high percentage 
of the
time no matter the method. But they may have to compromise or use other 
strategies
in order to do it. For instance...
 
Here are the percentage of elections in which at least a quarter of the voters 
ended up
compromising (favorite betrayal). The three figures follow the order of the 
scenarios 
above.
 
WV 0.4%, .02%, 0% of elections
IRV 9.3%, 4.6%, 5.7%
MCA 0%, 0%, 0%
Range 0%, 0%, 0%
Approval 0%, 0%, 0%
FPP 17.4%, 17.3%, 18.7%
 
I could have produced other figures as well, such as the rather alarming burial 
rate
under WV. But the point is just that the Condorcet efficiency with strategic 
voters,
this single figure, doesn't tell a complete story.
 
Another point is that I'm not using one cookie-cutter strategy for all methods 
here.
The voters' strategy is deduced by AI, not by me.
 
I do realize I need to get around to making more of my work available.
 
Kevin
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