Bottoms Up for Herman Beun
ntk at netcom.com
Wed Jul 29 20:03:06 PDT 1998
Absolutely--Unless perfectionism is important to the party-members
to whom the method would have to be advocated, then Rank STV(MO)
is likely to be unnecessarily complex, for the amount of improvement
I was following the principle of trying to maximize the likelihood
that the STV result used would be the right one, by giving precedence
to the STV result whose N is more likely to match the number of
seats that the party wins. So it's about probabilistic perfection.
My rules would give precedence to the N that is closer to the number
of seats won in the previous election, on the assumption that that
number of seats is the most likely again.
True enough: House nonmonoticity is probably rare, and then, even
when house nonmonoticity occurs in the procedure's results, it
probably won't be right at or next to the N that equals the
number of seats that the party wins. Of course if the party
wins a few seats more or less than last time, then my procedure
would sometimes be giving precedence to the wrong count anyway.
So sure--for simplicity & brevity of rules, it's probably better
not to use 2 different precedence rules. That hadn't occurred to
me about the previous fractie-size being a problematic added input,
but maybe, especially when weighed against the need.
I don't consider the house nonmonotonicity to be a problem, however,
because that's just part of STV. So yes, the complexity issue
is the more decisive one.
As for the single-winner method for the 1st count, where N=1,
sure, it would be unlikely to win just 1 seat. In any case, it
could be argued that it's simpler to use the same method for
each N, meaning that (ugh!) STV would be what people would expect
the procedure to use for N=1. You'd have to weigh the simplicity,
avoiding the use of a different rule for N=1, and the improbability
of using the N=1 result, against the aesthetic aspect of even
having STV with N=1 in the rules. Again, having one less thing
to explain could outweigh the aesthetics.
But, on the other hand, you can't get away from having to use
some kind of single-winner method. Because, in the event that
house nonmonotonicity _does_ occur, even Rank STV(NL) has to
choose which of the entirely new candidates among the latest N
shall get the Nth place in the list.
Again, considering the rarity of house-nonmonotonicity, there's
certainly a case for saying to just go by which one has the
most 1st choice votes.
But I claim that it would go beyond unaesthetics, and would
set a bad precedent, if IRO were specified by the procedures
rules for choosing which new STV winner gets the Nth seat.
Consistency doesn't require use of STV for that single-winner
choice, since it isn't part of the sequence of N-candidate STV
elections. It's a special single-winner election for a rare
I realize that introducing a new rank-balloting count rule
for a rare occurence would create a whole additional explanation,
and possibly a time-consuming & consensus-threatening debate.
The rarity of nonmonotonicity suggests just giving the Nth seat
to whichever not-previously-listed candidate among the latest
N has the most 1st choice votes.
Because, either you want to go for simplicity or merit. IRO
wouldn't give either. The reason for using IRO instead of
most-first-choice-votes (FPP) would be if you believe that that
rarely-needed sw choice matters enough to not use FPP. But if
you believe that, then IRO doesn't make the grade either.
So, simplicity of definition & explanation seems to point toward
giving the Nth seat, in the nonmonotonic situation, to the
new STV winner with the most 1st choice votes.
As for Tideman's method, as I understand it, it doesn't offer
anything that Schulze's method doesn't offer. Its rule is
probably more difficult to explain or describe. Tideman may
meet Independence from Clones, but it seems to me that it
, in a different (& more likely) subcycle situation, causes
a worse violation than the one that it avoids. That's why
I haven't mentioned it when listing EM's better methods.
I personally don't count it among those.
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