[EM] Intro to list (etc)

[Stephane Rouillon]

There is a way to assign a number to every candidate at the end of a
Condorcet process but I am not sure it would fit your need. To be precise
that procedure finally assigns every vote to the voter's favorite candidate
among the acceptable candidates. It is clearly not a proportional ending
but I do not think you aim for multiple-winners elections using multiple
seat circumscription, so maybe it fits your needs.

This would be called Condorcet using sequential dropping and residual
approval weights.
Saddly(?) the website I posted this model is gone but I can send it back to
you
and you could find somewhere in electorama's archives (date 16/10/02)
more details and other versions...

Elisabeth Varin/Stephane Rouillon a écrit :

> Objet:
>               [EM] J)Ranked pairs using relative margins, sequential
> dropping...
>  Renvoyé-Date:
>               Wed, 16 Oct 2002 00:14:08 -0700
>    Renvoyé-De:
>               election-methods-list at eskimo.com
>          Date:
>               Wed, 16 Oct 2002 03:14:01 -0400
>            De:
>               Elisabeth Varin/Stephane Rouillon
> <stephane.rouillon at sympatico.ca>
>        Société:
>               Solutions 3000
>             A:
>               Election Methods List <election-methods-list at eskimo.com>
>
> ...and residual approval weights
>
> Summary:
>
> This method is like the previous one (K) excepted that the elimination
> order is definer by a ranked pair path instead of the number of 1st
> preference votes. It mixes IRV, Ranked Pairs and Approval methods.
>
> Explanation:
>
> The input is Demorep's preferential and
> approval ballot. We use ? to represent
> unranked candidates. Using the election-methods-list
> notation, we will use >> to indicate the approval
> limit.
> So acceptable candidates >> unacceptable candidates.
> For example: A > C > E >> D > B.
> We apply ranked pairs with relative margin.
> In case of equality, each ranking scenario is done,
> the final result is the average of the scenarios (well weighted).
> When the last candidate is eliminated, we check what is his residual
> approval rating. He receives one residual weight for each ballot where
> he is the last active candidate higher than >>. Elimination should not
> modify the ranked pair order.
> If the approval limit >> is not mentionned we suppose it could be
> added at the end. The winner is the candidate with the highest
> approval rating, not necessarily the latest eliminated.
>
> Example:
>
> 26: A > E > B >> C ? D
> 25: B > E >> A ? C ? D
> 24: >> C > E > A = B ? D (None ballots with lesser evil details)
> 23: D > E >> A ? B ? C
> 1: E >> A ? B ? C ? D
> 1: A ? B ? C ? D ? E (Blank ballot, a none ballot would start by >>)
> Locking produces:
> E>D (53/99)
> E>C (51/99)
> E>B (49/99)
> E>A (47/99)
> B>C (27/75)
> A>D (3/49)
> B>D (2/48)
> A>C (2/50)
> C>D (1/47)
> A>B (1/75)
> Resulting ranking: E > A > B > C > D.
> Elimination produces the weights:
> D => 0 residual approval.
> C => 0 residual approval.
> B => 0 residual approval.
> A => 0 residual approval.
> E => 75 residual approval.
> and 24 none ballots and 1 blank ballot.
> Final ranking: E(75) > A = B = C = D  (0)
> E wins.
>
> Advantages:
>
> The method does not encourage cloning.
> Trying to identify a lesser of two evil cannot help elect it.
> The method has weights as output so it can be incorporated
> into a fully proportional multiple-winners method.
> None and blank ballots can be differenciated, so they could have
> different consequences in a multiple-winners method.
> This methods guarantees the election of a Condorcet winner
> if it exists and is approved by all ballots.
> It resists well against vote-splitting because it is pairwise
> comparison based.
>
> Disadvantages:
>
> It is not monotonic.
>
> Previous explanations:
> http://groups.yahoo.com/group/Electoral_systems_designers/message/77
>
> Steph.
>
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Rob Brown a écrit :

> Hi all,
>
> I have lurked on this list on and off for a few years (the whole Nader
> thing in 2000 really got me interested in how thorougly broken plurality
> systems are).  Now I'm working on a web-based Condorcet based election
> system, so I figured I'd drop in and introduce myself, and see if anyone
> has any thoughts on the issue I'm having.
>
> I'm a programmer (c/c++/java/javascript) with an industrial design
> background, so I tend to be big on UI and graphical stuff. I have also
> dabbled in fuzzy logic, collaborative filtering, people matching and the
> like for a good while.
>
> Here is a UI I am working on for doing for ranking
> candidates:    http://weblogz.com/voting/2000pres.html
> This demo is of course based on the 2000 presidential election, and allows
>
> you to rank candidates with a (hopefully) friendly UI.  I avoided having
> people manually assign numbers to candidates  (after all, they are sitting
>
> in front of a perfectly good computer which can do that sort of thing
> well!), and I tried using a little animation, which seems to help in
> making
> it easy for voters to follow what they are doing.
>
> On the back end, I don't have any problem with figuring out how to
> tabulate
> the results, in terms of who is the first choice, who is the second, etc.
> I
> am using the Condorcet method, and using  ranked pairs to break ties.  No
> problem there....
>
> Now I need to figure out how to display results, in a way that makes sense
>
> to people.  The people I have talked to who are likely to use this system
> want to see more information beyond just the final ranking of candidates
> --
> they want to see some kind of "score" or a graph.  They are used to web
> based polls where you can see a nice little graph, showing how many voted
> for which candidate.  Knowing whether an election was neck-and-neck or a
> landslide is relevant information people should be able to see, I think.
>
> I have tried showing various things:  for instance, I can show a Borda
> count score.  But of course the Borda score does not always correllate
> with
> the Condorcet outcome:  you could have a higher score for a lower placed
> candidate, and that will confuse people.
>
> Another thing I tried was showing a score which is the sum of all margins
> by which they beat (or lost to) every other candidate.  For instance, if
> 20
> voters placed B above A, and 10 placed A above B, that would add 10 to B's
>
> score and subtract 10 from A's score. Again, though, it may not correllate
>
> with the Condorcet ranking, although for some reason my feeling is that
> this type of score is "better" than a Borda count. (is there a name for
> such a way of scoring?)
>
> So has anyone tried showing bar graphs or numerical scores for Condorcet
> elections?  I suspect that if this is completely impossible to show
> something reasonable, I won't have much luck selling a condorcet based
> system to a mainstream web audience....people really seem to want to see
> something to help them understand the results.  On the other hand, my gut
> feeling is that there MUST be some way to have Condorcet results equate to
>
> numerical values.
>
> Any thoughts?
>
> -rob
>
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