[EM] Re: Empirical data on cycles

Rob LeGrand honky1998 at yahoo.com
Sat Sep 3 22:44:19 PDT 2005

Adam Tarr wrote:
> It suggests to me that _natural_ cycles are very rare. This does
> not automatically mean that cycles can never be a problem. The
> important thing is to pick a Condorcet method where, when a
> Condorcet winner exists in sincere preference, it is extremely
> rare than any faction has a tactic where they can cause a
> favorable cycle. (I am referring, of course, to winning votes.)

Any such cycle-creating strategy that exists under a margins method
also exists under the equivalent winning-votes method.  If the
margins strategy includes no equal ranking, the strategies are the
same.  If it includes equal ranking, such as changing sincere


ballots to


ballots, an equally successful winning-votes strategy would be


So such situations are no rarer under winning-votes than under
margins.  If anything, it seems to me that winning-votes might
provide more such opportunities to the strategic voter since equal
ranking has no effective equivalent under margins.  (But it's
usually more effective just to order-reverse anyway.)  It is for
this reason and the fact that winning-votes encourages equal ranks
near the top of the ballot and full ranking near the bottom even
when insincere (and even in the zero-info case!) that I prefer
margins to winning-votes.

Rob LeGrand, psephologist
rob at approvalvoting.org
Citizens for Approval Voting

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