Vote For and Against: Difference between revisions
m
no edit summary
imported>KVenzke m (→Properties) |
mNo edit summary |
||
| (8 intermediate revisions by 4 users not shown) | |||
Line 2:
If a ranked ballot were being used, this would be equivalent to the voter having to submit a complete strict ranking of the candidates. The voter would be counted as voting ''for'' the first preference and ''against'' the last preference.
This method has also been called '''Venzke Disqualified''' (or '''Disqualification''') '''Plurality''' or '''VDP'''. One reason to prefer this name is that the name "VFA" refers directly only to the format of the ballot that the method uses.
== Procedure ==
Line 9 ⟶ 11:
== Properties ==
If we suppose ranked ballots are being used, then in the general case VFA satisfies the [[Monotonicity criterion]], and what could be called the ''Majority
In the three-candidate case, VFA does satisfy the [[Mutual majority criterion|Majority criterion for solid coalitions]], and in one respect also Clone Independence: When the winner in a two-candidate race is ''cloned'', this cannot cause the loser of the two-candidate race to be elected.
Although VFA performs rather poorly with respect to criteria, it is as easy to count as [[Plurality voting|First-Preference Plurality]] or [[Approval voting]], neither of which satisfies the ''Majority
==== Variant satisfying Participation ====
VFA can be made into a version of [[Descending Solid Coalitions]], and so can be made to satisfy the [[Participation criterion]], by making a small rule change: Instead of only disqualifying a candidate receiving more than half of the ''against'' votes, disqualify every candidate who receives more ''against'' votes than ''for'' votes.
When this rule is used, the addition of a ballot can only disqualify the candidate ''against'' whom that ballot voted; it cannot cause any candidate to no longer be disqualified except for the candidate voted ''for''; and similarly that's the only candidate whose ''for'' vote tally can be increased.
In the original version, adding a ballot could cause a candidate to no longer be disqualified, by altering how many votes constitutes "more than half." This rule has the advantage that if a candidate is disqualified, there is no way to alter the votes that didn't vote ''against'' this candidate in such a way that this candidate wouldn't have been disqualified.
The variant rule doesn't share this property, and so voters would have incentive to vote ''for'' the strongest candidate they prefer, in attempt to keep him from being disqualified.
Also, under the variant rule it is possible to be elected with extremely few ''for'' votes. It's possible that the two strongest candidates could both be disqualified, giving the election to the candidate with the third-most ''for'' votes, no matter how few votes that is.
== Example ==
Line 20 ⟶ 34:
In this scenario, Memphis receives the most ''for'' votes. However, Memphis also receives more than half of the ''against'' votes, so that Memphis can't win. The winner is instead the option with the next-greatest ''for'' votes, Nashville.
Nashville also happens to be the [[Condorcet criterion|Condorcet winner]], but VFA doesn't reliably elect these candidates. Nashville only wins over Knoxville and Chattanooga due to possessing more ''for'' votes than either. If either Knoxville or Chattanooga had not entered the race, the other of the
== See also ==
*[[VFA Runoff]]
[[Category:Single-winner voting methods]]
| |||