# [EM] Election methods in student government...

Chris Benham chrisjbenham at optusnet.com.au
Thu Dec 21 08:58:29 PST 2006

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Tim Hull wrote:

> 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.

Tim,
Your gives voters a very big incentive to not vote for someone who they
believe will win anyway.
In the extreme case there could be a very popular candidate X that fails
to be elected because everyone "knew" that X would win the first seat,
so didn't vote for X to avoid losing ("using up") a point.

Take this election for 4 seats.

11: ABCD
05: D
09: EF

By my calculations with your  suggested method, it elects  DEAF. The ABC
faction erred by approving D.

11: ABC
05: D
09: EF

Now the winners are AEBF.  That isn't a proportional or fair result. D
has a Droop Quota and should be elected (or squeezed out in a tiebreaker,
but here the EF "list" easily wins the last seat). The winners should be
D, two from ABC and one from EF.

For a good single-winner method, I suggest DMC(Ranking). Voters rank
candidates they approve, equal-ranking allowed. Elect the Condorcet winner
if there is one. Otherwise eliminate the least-approved candidate until
one of the remaining candidates X is pairwise undefeated by any of the other
remaining candidates. Elect the first X to appear.

I also very much like the "full" version of DMC (that allows voters to
rank among unapproved candidates by entering an approval cutoff/threshold).
Even  "3-slot DMC" that uses a 3-slot ratings ballot, top two slots
interpreted as approval and default placement  in bottom slot, is in my
opinion
better than Approval or any other 3-slot method.

http://wiki.electorama.com/wiki/DMC

I might have some PR suggestions in a later message.

Chris Benham

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