[EM] IRV vs Plurality

[Chris Benham]

Juho  wrote (25 Jan 2010):

"I reply to myself since I want to present one possible simple method  
that combines Condorcet and added weight to first preferences  
(something that IRV offers in its own peculiar way).

Let's add an approval cutoff in the Condorcet ballots. The first  
approach could be to accept only winners that have some agreed amount  
of approvals. But I'll skip that approach and propose something  
softer. A clear approval cutoff sounds too black and white to me  
(unless there is already some agreed level of approval that must be  
met).

The proposal is simply to add some more strength to opinions that  
cross the approval cutoff. Ballot A>B>>C>D would be counted as 1 point  
to pairwise comparisons A>B and C>D but some higher number of points  
(e.g. 1.5) to comparisons A>C, A>D, B>C and B>D. This would introduce  
some approval style strategic opportunities in the method but basic  
ranking would stay as sincere as it was. I don't believe the approval  
related strategic problems would be as bad in this method as in  
Approval itself."
<snip>

The  "some higher number of points (e.g. 1.5)"  looks arbitrary and results
in the method failing Majority Favourite, never mind Condorcet etc.

51: A>B>>C
41: B>>C>A
08: C>>A>B

B>A 61.5 - 59,  B>C 112.5 - 12,  A>C 76.5 - 53

51% voted A as their unique favourite and 59% voted A above B, and yet B wins.

Chris Benham


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