[EM] Confirmed!: Condorcet efficiency of IRV > 2-stage runoff

[Bart Ingles]

This is in Merrill's book as well:

Making Multicandidate Elections More Democratic
Samuel Merrill, III
Princeton University Press, 1988

It's out of print, but can be tracked down through public or university
libraries via Inter-Library Loan.

The book includes several other election methods, and other scenarios
besides random profiles.

Hare seems to deteriorate a little more slowly than Runoff when the
number of candidates goes up, but still declines substantially.  And
both "crash" when the candidates are more clustered than the voters. 
Plurality was even worse on both counts.  The other methods were better.

Bart


Steve Barney wrote:
> 
> I've discovered a professional article on voting theory which seems
> to confirm my argument (see
> <http://groups.yahoo.com/group/election-methods-list/message/9057>)
> that the IRV is more likely to elect a Condorcet candidate when one
> exists (with sincere votes) than the two-stage runoff procedure
> (assuming that the preferences remain fixed from one stage to the
> next). Here is an excerpt from Table 1, page 6 (in this article, IRV
> is called the "Hare" method):
> 
> Table 1: Condorcet efficiencies for a random profile with 25 voters
> by Merrill (1984)
> procedure \ # alternatives 2 3 4 5 7 10
> RUNOFF 100,0 96,2 90,1 83,6 73,5 61,3
> HARE (TIES) 100,0 96,2 92,7 89,1 84,8 77,9
> 
> See pg 6 of the article:
> 
> "Analysis of voting procedures in one-seat elections:
> Condorcet efficiency and Borda efficiency"
> DIMITRI VANDERCRUYSSEN (KUL)1
> March 1999
> <http://citeseer.nj.nec.com/vandercruyssen99analysis.html>
> 
> That article notes that this "far-famed table" comes from an earlier
> article:
> Merrill, S., III (1984) “A Comparison of Efficiency of
> Multialternative Electoral Systems”, American Journal of Political
> Science, Vol 28, Issue 1, pp. 23-48.
> (available in the "JSTOR" academic database)
> 
> Notice that, just as I surmised, the two methods start out equivalent
> with 2 or 3 candidates, and then the IRV does better and better than
> the 2-stage runoff as the number of candidates grows.
> 
> Also, on a lighter note, this article cites this list in footnote 9
> on page 6:
> 
> 9 "We use the name “Baldwin” rule in order to stress the difference
> with the Nanson rule. John Taplin mentioned that name on the Election
> Methods Internet Site. The procedure may be better known as e.g.
> Nanson’s modification of his own rule (cf. McLean and Urken (1995)),
> but this terminology is confusing."
> 
> =====
> Richard M. Hare, 1919 - 2002, In Memoriam, http://www.petersingerlinks.com/hare.htm
> 
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