electionmethods at votefair.org
Thu Mar 29 13:45:47 PDT 2018
Another proportional method that uses a Condorcet method (Kemeny) as its
foundation is VoteFair ranking.
Specifically VoteFair representation ranking handles two winners per
district, and VoteFair partial proportional ranking handles the filling
of (extra) nationwide (or statewide) seats.
The "partial" aspect can be adjusted to become fully proportional, just
by adding more nationwide seats.
On 3/28/2018 1:47 PM, Kristofer Munsterhjelm wrote:
> On 03/28/2018 08:08 PM, Curt wrote:
>> Incidentally, this does point to what I believe *is* a major downside
>> of a Condorcet method - it’s by definition entirely unsuitable for
>> figuring proportional representation, because that again would imbuing
>> vote margins with utility concepts.
> The Condorcet property (or even the majority property) is incompatible
> with proportional representation. The usual example is something like:
> 51: X1>X2>X3>X4>X5>X6>X7
> 49: Y1>Y2>Y3>Y4>Y5>Y6>Y7
> Suppose we want to elect four winners. The proportional outcome is to
> have two Xes and two Ys, probably X1 X2 Y1 Y2. But applying the majority
> criterion forces the election of X1, and after X1 is out of the picture,
> it forces the election of X2, and so on until four X-es have been elected.
> Majority and Condorcet simply are the wrong tools for the job of PR.
> That said, there are methods that pass Condorcet when there's only one
> candidate to elect, and pass the Droop proportionality criterion when
> there's more than one to elect. One example is CPO-STV, and another is
> Schulze STV.
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