[EM] Proportional multi-winner ranked voting methods - guidelines?
electionmethods at votefair.org
Sun Feb 26 21:44:38 PST 2017
On 2/23/2017 12:08 PM, Toby Pereira wrote:
> Does the VoteFair method obey a specific proportionality property? For
> example, if you insist on electing the Condorcet winner, this is
> incompatible with Droop proportionality - e.g.
In VoteFair ranking, the first seat in a district is won by the winner
according to the Condorcet-Kemeny method. The winner of the second seat
in the same district is determined by first proportionally reducing the
influence of the voters who are already well-represented by the first
winner, and then with the remaining preferences, calculating the
So, yes, those results are Condorcet compliant. Obviously those results
alone do not assure proportional results.
For the proportional part of the results, some "nationwide" seats in
parliament (or the legislature) are reserved for proportionality
adjustments. The criteria for winning them is not mathematically
sophisticated (because it involves comparing the popularity of
candidates who were not in the same race), so I doubt that the result
meets any sophisticated proportionality criterion. And I doubt that the
results meet Droop proportionality because that calculation method is
With VoteFair ranking, a greater number of nationwide seats increases
proportionality, but that reduces the number of seats filled by the
carefully selected -- Condorcet-compliant -- district-based winners.
It's a balance that needs to be adjusted according to the needs of the
nation using it.
As a clarification, VoteFair ranking does not attempt to achieve fully
proportional results for every political party.
Instead it attempts to ensure that the majority of elected MPs (members
of parliament) best represent the majority of voters, keeping in mind
that political parties are often not really representative of voters.
This concept relates to what's currently going on in U.S. politics.
Most U.S. voters are not well-represented by either the Republican party
or the Democratic party. In particular, if fair methods of voting were
used here, none of the candidates who were in the primary elections
would have won those primary elections.
Expressed another way, voters want problem-solving leaders, but unfair
election methods give us special-interest puppets.
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