[EM] Election methods in student government...

Thu Dec 21 04:34:51 PST 2006

  > From: thully at umich.edu
 >
 > Anyway, I have been investigating alternate systems for single-winner
 > elections and (especially) multi-winner elections. Party list is out
 > - the less rigidly-defined party structure makes it even less fair
 > that it would be in a national election.

 There is a system called open party list. Basically, the voter votes
 for 1 candidate. The party that that candidate represents gets the vote
 and the seats are split on that basist between the parties. However,
 the party member that actually fills each seat is determined by how many
 votes the candidate obtained for the party, e.g. the party's highest
 vote getter gets the first party seat and so on down until all the party
 seats are filled.

 This allows the voters to choose the parties but also choose which
 party member gets elected.

 > I have also investigated STV (and IRV for single-winner) However, the
 > lack of monotonicity is quite troubling - the fact that you can help
 > elect a candidate by ranking them LOWER seems almost undemocratic.

 In the multi seat case, I don't think PR-STV is that bad.

 > This, coupled with the fact that the current system *replaced* STV
 > some 20-odd years ago, dampens my enthusiasm for that method a bit.

 That doesn't mean that STV is bad, it just means that it is bad for
 the majority. Any PR system is bad for the majority.

 Look at what the new system actually does ... it give most of the
 seats to the majority party/faction. Who decided the current system?
 Presumably, it was the majority party/faction.

 > I have also seen plenty of other election methods that look interesting
 > - Concordet methods especially. However, these methods are quite complex
 > and don't have any good multi-winner variant (there is CPO-STV, but it is
 > extremely complex and is still non-monotonic).

 I would suggest asset voting as a really simple way to get PR.

 In its most simple form, each voter votes for 1 candidate. Any candidate
 who gets the quota is elected and can transfer his excess to any other candidate.
 All the other candidates can also transfer votes in order to bring one of
 them to the quota.

 > Right now, I'm kind of at a loss as to what the best voting system would be.

 It depends on your objectives. There is no 'best' system.

 > It's obvious that the current system isn't it

 Yeah, it does seem pretty bad.

 > I also don't like the idea of using a system that is so complex that
 > it can't be reasonably explained to non-technical types.

 > I also don't like the idea of using a system that is so complex that
 > it can't be reasonably explained to non-technical types.

 There is also the problem that if it is that complex, explaining it to
 the vote counters could even be a problem. Also, some of them require a
 computer to count the votes. IMO, that is to complex for a student
 government.

 > regular STV is about at the maximum complexity I would want

 This is one way to give the rules for asset. It is not the full
 transfer method though, but it gives clear rules for the transfers.

 You could maybe describe it as PR-STV, but that the candidates decide
 the transfers. However, maybe that would be a bad idea if PR-STV has
 bad press.

 (Anyway, here's my suggestion for the rules)

 The candidates, equal in number to the number of seats to be filled,
 holding the most votes, shall be given the option of transferring
 some of their votes to other uneliminated candidates. Each of the
 candidates shall decide how many of their votes and to whom to
 transfer them to. After, the transfer has been completed, a candidate
 shall be eliminated. If no candidate volunteers, the candidate with
 the fewest votes shall be eliminated. The eliminated candidate shall
 be given the option to transfer any votes held to other candidates.
 This two step process shall be repeated until the number of uneliminated
 candidates is less than or equal to the number of seats to be filled.
 The remaining uneliminated candidates shall be deemed elected.

 It also allows a candidate to volunteer to stand down. This helps 
 with monotonicity issues.

 > Even standard STV is almost too complex - part of the reason it was
 > originally eliminated is due to its complexity! Due to these reasons,
 > ease of use, understanding, and transparency is paramount.

 Maybe I am being cynical, but I would say that was the excuse rather
 than the reason (or at least only part of the reason).

 > So far, all I have came up with which seems to potentially be a good
 > method is a variant of sequential proportional approval voting. Under
 > the system, single winner elections would be simple approval voting.
 > However, for multi-winner elections each student would begin with a
 > set number of "points" equal to the number of seats to be elected.
 > Votes would be counted as in normal SPAV, and each weighted according
 > to the number of points each student has remaining. Every time a voter
 > elects one of their choices, they would "use up" one of their points.
 > This seems a little more understandable than standard SPAV, and it
 > hurts groups that share some preferences with the majority less.
 >
 > Is there something that would potentially be better while not becoming too complex?

 You are basically weighting each ballot as

 E = number of elected candidates on ballot.
 N = number of seats

 Your way:

 (N-E)/N

 (the divide by N is to just rescale it, so the 2 match for E=0)

 instead of

 Normal method:

 1/(1+E)

 Assuming, 5 seats,

 E (normal) (your way) 
 0: 1 1
 1: 0.5 0.8
 2: 0.33 0.6
 3: 0.25 0.4
 4: 0.20 0.20

 Your system greatly decreases the penalty for electing a candidate.
 This will be a benefit to larger parties. The normal way has the advantage
 that a faction of a Droop quota always gets a seat, while under your
 system it doesn't.

 I think in a small number of seats case, it may not be quite as big a problem.

 However, if there were 5 seats and 3 parties with

 A: 77%
 B: 22%
 C: 21%

 A got 3.85 seats
 B got 1.1 seats
 C got 1.05 seats

 A will get the first 3 directly.

 Round 4:
 A: 78 * ( 5-3) = 154
 B: 22 * ( 5-0 ) = 110
 C: 21 * (5-0) = 105

 A wins again

 Round 5:
 A: 78 * ( 5-4) = 78
 B: 22 * ( 5-0 ) = 110
 C: 21 * (5-1) = 105

 B wins

 A wins 4 seats and B wins 1 seat. However, C had more than 1/5 of the votes
 so should have won at least 1 seat in a 5 seater election.

 > ... and not to complex

 Asset has the advantage that the voting stage is very easy for
 the voters .... just pick your favourite candidate.

 The candidates then move around the votes after the election in order to
 give PR.

 You can't get much less complex than that.

    Raphfrk
 --------------------
 Interesting site
 "what if anyone could modify the laws"

 www.wikocracy.com    
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