[EM] Forest--Your method proposal
mikeo2106 at msn.com
Fri Jun 29 13:16:17 PDT 2007
The use of those checkmarks to inform automatic strategy is a shortcut to
DSV's way of determining each voter's best strategy.
It was you who first suggested that it's in a voter's best interest to
approve every candidate who is better than that voter's expectation in the
election. Several of us agree, including me.
Automatically having each ballot approve every candidate that it ranks above
the most likely winner is a rough approximation to that, when we let the
merit of the most likely winner stand in for your expectation.
But then wouldn't it be better to use a simplified DSV that automatically
has everyone approve everyone they like better than the winner of the
previous count? Wouldn't the previous count's winner be a better estimate of
the most likely winner?
That would be easier to explain to people than would Hoffmann's or Crannor's
calculation of the pairwise tie probabilities based on previous elections. I
don't know how much merit difference there'd be between these different
automatic strategy methods for DSV.
One suggestion for your method and for DSV: For public acceptance, it's got
to be optional. The voter must have the option to manually place his/her
Approval votes, instead of letting DSV or any other automatic process do so
Some years ago I looked at a method that, based on everyone's rankings,
elects the candidate who'd win at Nash equilibrium in (say) an Approval
vote. From the examples I looked at, it seemed as if that method had
properties very similiar to those of wv Condorcet. And, though DSV was more
difficult to examine in that way, my impression was that DSV is similiar in
that regard. If these attempts at idealness--DSV and Nash Equlibrium
Selection--have the properties of wv, then that gives strong support to wv,
as the best that one can do, for strategy-freeness.
I suspect that wv can't be beat for strategy freeness by any
nonprobabilistic method. Of course wv, and other methods with similar
properties, such as MDDA and MAMPO, can have their strategy-freeness greatly
enhanced by add-on options such as ARLO.
Jobst suggested a method, or a class of methods, that matches wv, by trading
Condorcet's Criterion for FBC. With some electorates that would be better,
but the important thing is that both kinds of methods are equally good; it
simply depends on which of those two criteria you choose. Timid,
overcompromise-prone voters need FBC more than Condorcets Criterion.
One strategy improvement over wv would be to disqualify majority-beaten
candidates, even if it means disqualifying everyone. That would guarantee
that if a majority prefer X to Y and vote sincerely, Y can't win--without
all the stipulations of SFC and GSFC. But of course it would be
prohibitively indecisive. So that method demonstrates a limit on how
strategy-free a method can be.
The subject of how good a nonprobabilistic method can be, in terms of
strategy-freeness is an interesting one. Those are my impressions about it.
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