Single Winner Methods Pros and Cons

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Single Winner Methods Pros and Cons

Craig Carey-2
[posted earlier on ER list]

I rank single winner methods, as follows--

1. Condorcet (with a disapproval vote)- with multiple same choice votes known
as Multiple Same Choices (MSC)
Pro- Makes head to head comparisons
Con- Explaining possibility  of circular ties with tie breaker to voters,
some candidate/voter strategy regarding second choice votes if 3 candidates
especially, winner may be by a minority only

2. Approval Voting (AV)
Pro- Very simple to vote (noting that the range of approved candidates may be
rather narrow), winner has most approval of voters
Con- A losing candidate might be a Condorcet unique winner, winner may be by
a minority only (due to probable voting for a limited number of candidates-
i.e. ballot truncation)

3. Majority Preference Voting (MPV) also known as Instant Run-Off (IRO)
Pro- Simply produces a majority relative winner (and an absolute majority
winner if enough voters make enough rankings),
Con- Winner might lose to one or more losing candidates head to head

4. Plurality
Pro- Very simple to vote
Con-Winner is by a minority in most cases. Winner might lose to one or more
losing candidates head to head

Are there any other single winner methods ?

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Single Winner Methods Pros and Cons

Craig Carey-2
I already stated, in my ER reply to that message, why I disagree
with the "cons" that it lists for Condorcet.

As for other methods, sure, but our committee should, at first at least,
deal only with the methods that are proposed to it:

Condorcet
Double-Complement
Copeland
Approval
IRO (MPV)

Later the FAQ can be expanded to other methods if desired.

I should add Condorcet+NOTB & Condorcet+Disapproval to that
list.

Mike



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Single Winner Methods Pros and Cons

Craig Carey-2
In reply to this post by Craig Carey-2
According to Jerry S. Kelly ("Social Choice Theory," Springer-Verlag, 1987,
p62):  "... [for] a relatively simple case with just five individuals [voters]
and four alternatives ... the number of possible social choice rules is ...
approximately 10^235,000,000,000 ..."

Bruce