Jeff wrote ...
Now that we have presented a few favorites and examined them, I hope we all
at least understand each other, even if we do not yet agree. It now looks
like we have the following:
* DMC has one ardent supporter and several contributors who think it
acceptable.
* Shulze (WV) is widely acceptable, already in use, and hated by none.
* Smith//Approval is widely acceptable, but it has a few detractors who
sense burying.
I reply:
Shulze and Smith//Approval have been around the
longest, so they are more widely known than DMC.
But let's compare them head-to-head with
DMC.
DMC is identical to Shulze when defeat strength is
measured by winning approval (instead of winning votes). The only
disadvantage of DMC in this comparison is that it requires an approval
cutoff. In all other ways, including ease of description, DMC
is as good or better than Shulze.
In particular, because Shulze lacks approval
information it cannot take it into account. Because of this DMC tends
to pick a better winner than Shulze under zero-info sincere
voting.
On the other hand, "winning approval" is a more robust
measure of defeat strength than "winning votes." Because of this fact,
Shulze is at least as vulnerable to strategical manipulation as DMC is. To
understand this better see the example I posted this morning to both
the Condorcet and the EM list. [It hasn't shown up yet on the Condorcet
list.]
As in Smith//Approval the DMC winner always
comes from the Smith set. When the two methods choose different members of
the Smith set, DMC chooses the pairwise winner of the two, while Smith//Approval
chooses the one with the higher approval. So Smith//Approval favors
approval information over pairwise information compared to DMC.
I would rather see plain old garden variety Approval
or Range(-1,0,1) than Smith//Approval, which seems like a cobbled together kluge
in comparison with DMC.
Also, as has been pointed out, the Smith//Approval
winner X can lose pairwise to the Smith//Approval runner up Y.
In other words it can happen that in a runoff between the winner X and
the candidate Y who would have won had the winner dropped out, this
candidate Y would win.
DMC is not afflicted by this problem.
The perception that Shulze is more widely acceptable
than DMC may be an illusion due to the fact that members who have not weighed in
on this issue consider the 15 reasons to be so definitive as to
make the conclusion obvious.
In my opinion the best
Condorcet proposal is DMC. I suspect that a majority of members
who have read the fifteen reasons would agree.
However, if there is no simple ballot option for the
voters who don't want to rank the candidates, i.e. for those voters that would
rather delegate that task to their favorite, then in that
case Approval is a better public proposal.
Peace,
Forest
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