[EM] RE : Re: Election methods in student government...

[Dave Ketchum]

Too late at night to remember exactly what LNH means but, assuming it 
REALLY calls IRV better than Condorcet, I have to offer a compensating 
example.

Given:
   37 A
   31 B<C
   32 C

Condorcet and IRV will agree with humans who look at the numbers without 
studying election methods - that C is liked better than B, and twice as 
deserving as A, thus that C is the proper winner.

Now add in two troublemakers who came in late and see what they can do:
      2 A - C still wins.
      2 B - IRV declares A the winner, while this does not disturb 
Condorcet (there is a cycle - 37A>33B>32C while 65C>37A).
      2 C - C still wins.

What it all means:  Condorcet looks at all that the voters say, while IRV 
takes shortcuts.

DWK

On Thu, 21 Dec 2006 11:51:53 -0500 Tim Hull wrote:

> OK, wasn?t sure about Condorcet - I knew that to meet the Condorcet 
> criterion with a voting method you had to violate later-no-harm, but not 
> that the finding of a Condorcet winner in and of itself violated LNH.  
> Thanks for clearing that up...
> 
> Regarding the single winner methods, it seems that IRV or MMPO may be 
> the way to go there if one wants to maintain later-no-harm.  Range seems 
> to be a good choice with respect to non-LNH compliant methods, and 
> reweighted range for multi-winner.
> 
> I?m curious - is there any other multi-winner PR methods (besides STV) 
> that satisfy later-no-harm, exclusing variants of party list and asset?  
> Also, what tie-breaking methods for IRV/STV/MMPO satisfy LNH?
> 
> I figure that the decision mostly comes down to whether LNH or 
> monotonicity are more important in our elections.  I know many people 
> will bullet vote - probably more than in a hypothetical national 
> election - if the voting system fails LNH.  However, monotonicity is 
> also a concern...

-- 
  davek at clarityconnect.com    people.clarityconnect.com/webpages3/davek
  Dave Ketchum   108 Halstead Ave, Owego, NY  13827-1708   607-687-5026
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