[EM] Newbie de-lurks to propose a clone-proof Borda method

[Chris Benham]

Ken,
Interesting. How exactly does one calculate the  "correlation" of  the 
pairs of candidates?

Chris Benham





Ken Kuhlman wrote:

>
> I've recently become interested in election methods, and have noticed 
> that while the Borda count has been shown to have many desirable 
> properties, it is customarily dismissed because of its susceptibility 
> to clones.   The method proposed below, which I call "Correlated 
> Instant Borda Runoff," is basically a tweak of Baldwin to solve the 
> clone problem.
>
> Individual ballots are scored according to the Borda count, and then 
> all possible candidate pairs are ranked according to correlation.  The 
> Borda loser of highest correlated pair is eliminated, and the next 
> round proceeds with the remaining candidates.
>
> Under this method, clones can be seen as a special case of correlated 
> pairs (they're perfectly correlated), and so the Borda loser of a 
> clone pair is eliminated immediately, before they can spoil the election.
>
> For example, consider an election between A, B, and C, where B & C are 
> clones:
> 1:A>B>C
> 1:B>C>A
>
> While Borda gives the election to B, CIBR recognizes BC as highly 
> correlated (and thus a clone), and so eliminates C and declares the 
> election a tie between A & B.
>
> Note that if the clones are transposed on the second ballot, as below:
> 1:A>B>C
> 1:C>B>A
>
> Then AB are clones as well, and the election becomes a three-way tie.  
> (The Borda property of declaring symmetrical elections ties is 
> retained under CIBR).
>
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