[EM] strategy-free Condorcet method after all!

Kristofer Munsterhjelm km-elmet at broadpark.no
Mon Nov 23 11:16:19 PST 2009


robert bristow-johnson wrote:
> 
> On Nov 23, 2009, at 1:43 AM, Dave Ketchum wrote:
> 
>>
>> Seems to me that cycles can occur even with sincerity - they relate to 
>> conflict among three or more voter views.
> 
> 
> sure, they "can".  but i still question the prevalence of such 
> happening.  and with the other methods, particularly the two used in 
> governmental elections: FPTP and IRV, the prevalence of tactical voting 
> (particularly compromising) is clear.  why is there so much worry about 
> a pathology that just doesn't seem to occur often enough to be worth it 
> when there seems to be plenty reason to worry about pathologies involved 
> with the non-Condorcet methods?
> 
> i dunno how to, other than take the raw ballot data of some existing IRV 
> elections, but i would like to see how many of these municipal IRV 
> elections, that if the ballots were tabulated according to Condorcet 
> rules, that a cycle would occur.  i know the answer for Burlington 2006 
> and 2009 (no cycle in either case, the first case the IRV, Condorcet, 
> and FPTP winner was the same person, the second case they were 3 
> different persons, a clear pathology worth worrying about).  what about 
> Cambridge MA or SF, anyone know?

Warren Smith has a copy of Tideman's election archive, as well as some 
other data, here: http://rangevoting.org/TidemanData.html

I haven't run the data through my simulator yet, but it seems cycles are 
rare.

There's also a database of STV elections at http://www.openstv.org/stvdb 
. While they could be processed by my program (if I write the correct 
converters), they are multiwinner elections and so the frequency of 
cycles might not be relevant to what would be the case for when voters 
are told the election is single-winner.

Does anybody know of any data sources apart from the above?



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