[EM] Empirical data on cycles

Andrew Myers andru at cs.cornell.edu
Fri Sep 2 22:15:48 PDT 2005

I thought the folks on this list would find it interesting to see
some actual empirical data on how often cycles happen. I have data on
99 CIVS elections that have been run in which more than 10 voters
participated (max was 1749) and in which there were at least three candidates
(max was 72). These 99 elections break down as follows:

had a Condorcet winner:                                 85
no Condorcet winner, but a unique unbeaten candidate:   7
multiple unbeaten candidates in real ties:              3
real cycles requiring completion:                       4

These results suggest to me that the concern about cycles arising in Condorcet
methods is a bit excessive.

This is anecdotal, but I looked at the four elections in which cycles occurred,
and my impression was that these were usually elections with a lot of
candidates and a poorly informed electorate that couldn't effectively judge
between them.

-- Andrew

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