Ping ([info]zestyping) wrote,
@ 2005-03-29 04:02:00
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Condorcet elections.
This evening at our weekly house meeting, my house voted nearly unanimously to put Condorcet elections on the next paper ballot. If the bylaw change passes by a 2/3 vote, we will use Condorcet (specifically the Schulze method) for all house elections from now on.

Condorcet voting is based on a simple principle:
The Condorcet winner is the candidate who defeats all the other candidates in one-on-one contests.
In sports, a "round-robin tournament" is one in which each contestant is matched against every other contestant. Condorcet is instant round-robin voting.

In a Condorcet election, the voters are asked to rank the candidates by writing numbers next to candidates on the ballot. Voters can rank multiple candidates with the same number to indicate that they are equally preferred, and can leave candidates unmarked if they don't care about them. Voters can vote for one candidate if they want (as in plurality), vote equally for all acceptable candidates (as in approval), or provide more detailed rankings if they want.

To count the ballots, each candidate is compared with every other candidate in a one-on-one contest. For each contest, the ballots are counted based on which of the two candidates is ranked higher, thus revealing which one is more preferred by the voters as a whole.

Usually, one candidate will defeat all the others in these pairwise contests; that candidate is the Condorcet winner. In rare cases, it is possible for there to be no Condorcet winner; for example, it is possible that most voters prefer A to B, most prefer B to C, and most prefer C to A. The Schulze method resolves this ambiguity by successively disregarding the narrowest defeat until there is a winner.

(The Schulze method is known by many names, including "Beatpath", "Path Winner", and "SSD". On Wikipedia it is called Cloneproof Schwartz Sequential Dropping. This is the Condorcet completion method used by Debian and UserLinux.)

I was pretty surprised that there was such strong support for a method that is relatively complicated and requires a computer to run. I can hardly believe it, actually. But i'm delighted to see it. If this passes, Kingman will have the most accurate election method in all of the USCA.

To make elections feasible to run, i put together a Schulze implementation in Python and packaged it on a CD with the necessary scaffolding to make it run on Linux, Mac OS, and Windows. The files include detailed instructions. The interface is crude, but i tried hard to make it foolproof. The hope is that long after i'm gone someone will be able to just pop in this CD and successfully run a Condorcet election. Here is a zip file of the contents of the CD. If you feel like giving it a whirl, I'd love to hear feedback about what works or doesn't work, what is obvious or hard to figure out. Please feel free to take the distribution, use it anywhere, make your own CDs, etc.

Does anyone know of any other co-ops that use a Condorcet method? Or organizations of any kind, for that matter, other than those listed on Wikipedia?

I did a little reading about Tideman (ranked pairs) and Schulze (beatpath) when trying to choose a completion method, but couldn't find much information to help compare them on objective criteria. I'd be interested in hearing arguments for or against either option.

I still find approval voting to be more practical as a proposal for general election reform. Here's a nice colourful page illustrating how approval solves all of the important problems with plurality. Condorcet is a more expressive method than approval, and having Condorcet here in our small 48-member organization would be great, but i don't see how we could possibly get the general public to fully understand how a Condorcet election is conducted.


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[info]tongodeon
2005-03-29 02:24 pm UTC (link)
The links you provided seemed to answer every question I had except "where does the name 'Condorcet' come from?"

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[info]tongodeon
2005-03-29 02:28 pm UTC (link)
Doh, I didn't check the very last link:
The name comes from a deviser, the 18th century mathematician and philosopher Marquis de Condorcet

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[info]anthonybaxter
2005-03-29 02:27 pm UTC (link)
I'm curious why you think approval voting is preferably to preferential voting (I think the US calls it Instant Run-off Voting). This is the system used in the lower house here in Australia, and it seems to work ok - it allows third parties to attract votes, without having to worry about those votes causing a different candidate to sneak through (as for instance happened with Nader's votes away from Gore letting Bush through in 2000).

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[info]zestyping
2005-03-29 08:57 pm UTC (link)
Instant run-off is a deceptively problematic method for single-winner elections. I believe many advocates of IRV are confused about their chosen system. Here is a flyer i once wrote explaning the problems.

In short:
  • Voting for someone can make them lose in IRV under plausible and non-rare conditions. This introduces a new and severe problem that plurality does not have.
  • IRV does not actually remove the barrier to third parties, since it is only safe to vote for a third party if you are sure it will lose. IRV still works against third party that actually has a chance of winning, just like plurality does now. So voting for a third party is a purely symbolic gesture.
Putting these two facts together, the effect of IRV is like holding an opinion poll alongside the election, except that IRV is worse because it allows the symbolic votes to mess up the outcome in highly confusing ways. Thus i consider IRV to be not only the worst form of ranked voting, but even possibly worse than plurality voting.

In my opinion: for ranked ballots, a Condorcet method is the only reasonable choice; and for non-ranked ballots, approval is the only reasonable choice. Since i place a high value on simplicity, transparency, and the electorate fully understanding their own election system, i generally advocate approval.

I'm curious how it has worked out in Australia. I was under the impression that STV is effective in the Senate where it is used to elect multiple winners, but that it isn't effective in the House where it is used to elect one winner. (I'm using the term STV to refer to the general method, where IRV is single-winner STV. I'm avoiding the term "preferential voting" because it is horribly imprecise.) Isn't the House still mainly locked down by two parties? I'd appreciate if you could shed some light on that.

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[info]nwhitehe
2005-03-29 11:22 pm UTC (link)
Does Kingman Hall actually have interesting votes that could be affected by this? Very cool stuff.

My (small) experience with student voting is that electing people is usually pretty tame, but that voting on issues can be contentious. The way questions are phrased and presented makes a big difference in whether they pass. For example, UCSC used to have narrative evaluations instead of grades. Several years ago they switched to regular grades, with mandatory narrative evaluations. That was a very contentious move! There were special Senate meetings, parliamentary tricks, exactly even votes, the works. Maybe there is a nice way to adopt Condorcet voting as a general parliamentary principal. Rather than the whole process of movements, amendments, revisions, rules of order, there could be a new system that is much more free and fair by using Condorcet voting.

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Voting
[info]ianbicking
2005-03-30 05:30 am UTC (link)
Voting sometimes seems weird to me... especially in an intimate situation like a coop house. I'm used to using consensus in those environments -- it's no good to have someone feel overwhelmed by the majority, and if the decisions are actually important then everyone should also feel invested in the decision. Though there are also places where consensus doesn't work well -- like a single difficult person (who may be the subject of the decision process itself) -- and it collapses into peer pressure and filibuster-like tactics. But it still seems more civil.

But I don't know how that would work for elections. I guess that's why there's always committees and never officials. Hrm.

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[info]megjournal
2005-03-31 03:07 am UTC (link)
Interesting voting style...I kinda like it. In the 4 years of my poli sci degree, I don't think I came across it.

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Dorm Room Stories
[info]megjournal
2005-03-31 03:18 am UTC (link)
Hmm...how to describe our room in college... I'm not sure. It was definately bizarre, but it was so random and chaotic that it's hard to create an image since there was no theme.

We tended to rebuild the bunk beds on a regular basis. Basically you could take the dorm beds apart and collect parts from storage rooms to build them into odd heights or arrangements. We played with that a lot and managed to create a sort of 2 story (half stories really) dorm room with a "den" and "pit" under the beds that were raised up and set at whatever weird way we could think of. We had fun with the wardrobes as well. We also had a pink and purple shag carpet that we staged a custody battle complete with "court" at the end of living together. Once we put a lobby outside our room complete with table, magazines, chairs, phone, etc.

The BEST was what we did to my then boyfriend's room. He hates chaos and is the most efficient person I know. While he was out for a day, we moved his wardrobe in front of his window. The other one was in front of the door with barely enough room to get through the door. One bed was diagonal and one was against a wall. (Luckily he didn't have a roommate then.) That wasn't all. We paid attention to every details. We switched his desk drawers around. We even rearranged all the keys on his keyboard.
We were quite amused. He was not. Not at all. Never quite forgave me for that even though we put it back right after he saw it. But hey, it was chaos and it was fun!

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We use it!
(Anonymous)
2005-04-01 11:28 am UTC (link)
From your description, I'm pretty certain that that's the system our Student Union at Bath uses to elect sabbatical officers. Ironically, I didn't really understand some of the finer details before reading your discussion here!

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Re: We use it!
(Anonymous)
2005-04-01 11:29 am UTC (link)
Sorry, forgot to sign off -- that last was Meri (blog.meriwilliams.com)

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