Thanking Jameson for serious thinking.
The possibility of cycles should not scare us on election day - we
should be prepared for reasonable response for whenever they happen.
Such as:
A or B or C should rate as CW vs D thru Z (a 3-member cycle - 4 or
more are possible, but not considered here).
C beating A and B would make it CW - no cycle.
A and B beating C would make one of them CW - no cycle.
So a cycle requires 3 comparable contenders. Not likely the office
holder running - and having earned reelection or eviction. Likely
multiple groups of voters pulling in different directions, rather than
two sides of one issue.
Those doing models can lean toward demonstrating the event that
interests them, rather than average voter activity.
Out of all this voters should be educated that cycles are a normal
event seeable with Condorcet, whatever their frequency.
"Truncation" is a word that puzzles me. I see voters learning a bit
to pick candidates of possible interest, and then studying these few
to pick one, or a small group, to vote for. When they vote for one or
more I do not see the selection as being truncation.
What I read of burial makes it an education topic, for users too often
sound as if not understanding the topic.
On Jul 17, 2010, at 12:40 PM, Jameson Quinn wrote:
To clarify my position:
I think that, because of social dynamics which push voter groups
towards symmetry (ie, B voters like A as much/little as A voters
like B), honest condorcet cycles will be a fraction of what they
would be in "impartial culture"-type models. Since such models
usually give somewhere around 10% cycles, or a little more, I think
honest cycles will be somewhere in the low single digits - 1%-4%.
For this, I have little evidence, although it should be noted that
Romania is not at all counter-evidence; one documented possibility
in a large number of modern, polled elections is about what my
proportion would have predicted. It is certainly not evidence
against "most" cycles in a Condorcet system being due to truncation,
as we have essentially 0 data on condorcet systems in public
elections.
I think that the necessary conditions for truncation/burial to be a
rational strategy will be much more common. It depends a lot on the
average number of "serious" candidates per election, but assuming
that with a Condorcet method that number would be somewhere between
2.5 and 5, with a minimum of 2... well, I don't want to pretend I've
done the calculations, but my guess is that that would lead to
somewhere between 20% to 60% of elections having a rational
truncation which would affect the result. I'd imagine that a
possible truncation would actually happen somewhere from 25% to 75%
of the time. So honest cycles should be roughly 1%-4%, and truncated
ones roughly 5%-45%. If these broad ranges are right, then truncated
cycles will be 55%-98% of all cycles - probably 66%-90% - ie, "most".
This is why I think that system performance relating to truncation
strategy is at least as important as honest performance, at least
for decent systems where the differences between honest performance
are not too large.
JQ
2010/7/14 Warren Smith <[email protected]>
> I believe that Jameson Quinn is right when he says that most
Condorcet cycles are probably artificial,
i.e. they are caused by strategic truncation or strategic burial.
--For a real life example of a Condorcet cycle in a large national
election, see
http://rangevoting.org/Romania2009.html
Contrary to Simmons' conjecture/intuition, this cycle seems to have
been not "strategic," it was "honest" -- because the evidence for the
cycle consists of pairwise-poll data, and there is no motivation for
dishonesty in 2-man pairwise polls.
Further, other real-world cycle examples (?) are noted, discussed 2nd
half of section 4.
--
Warren D. Smith
http://RangeVoting.org <-- add your endorsement (by clicking
"endorse" as 1st step)
and
math.temple.edu/~wds/homepage/works.html
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