[EM] No evidence that IRV doesn't fail. Reasons why it must

Dgamble997 at aol.com Dgamble997 at aol.com
Fri Jan 23 13:24:01 PST 2004


Eric Gorr wrote:

>Condorcet did not elect the wrong candidate.  The voters were clearly 
>split, but both of the larger groups preferred the third option over 
>the primary opposition. As such, the highest utility candidate was 
>elected by Condorcet.

>Why do you believe that the first place preferences matter more then 
>the middle or final preferences? What is the basis for this 
>assumption?

There are 3 candidates in an election A,B and C. The votes and relative 
utilities are:

45 A1.0>B0.3>C0.1
8   B1.0>A0.6>C0.2
5   B1.0>C0.6>A0.2
42 C1.0>B0.4>A0.1

The Condorcet winner is B. Adding up the utilities of the candidates the 
winner we get

A: 45x1 + 8x0.6 + 5x0.2 + 42x0.1 = 55
B: 13x1 + 45x0.3 + 42x0.4 = 43.3
C:  42x1 + 45x0.1 + 8x0.2 + 5x0.6 = 51.1

A has the highest total utility, A is not the Condorcet winner.

David Gamble

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