[EM] Losing Votes (ERABW)

[Jameson Quinn]

Looks good. Similar to ICT, I think, and simpler (from my perspective).
What does "ERABW" stand for? This should have a good name; "Least
Disappontment Condorcef" or something of the kind.

2012/11/16 Chris Benham <cbenhamau at yahoo.com.au>

> I propose the following as a reasonably practical, "summable", Condorcet
> method:
>
> *Voters rank from the top however many candidates they wish. Equal-ranking
> is allowed.
>
> The result is determined from a pairwise matrix. On that matrix, ballots
> that rank above bottom
> any X=Y contribute one whole vote to X>Y and another to Y>X.
>
> Ballots that truncate both X and Y  have no effect on the X>Y and Y>X
> entries in the pairwise
> matrix.
>
> With the thus created pairwise matrix, decide the winner with Schulze
> (Losing Votes).*
>
> It isn't a big deal if  Ranked Pairs or River are used instead of
>  Schulze.  "Losing Votes" means
> that the pairwise results are weighed purely by the number of votes on the
> losing side. The "weakest
> defeats" are those with the most votes on the losing side, and of course
> conversely the "strongest
> victories" are those with the fewest votes on the losing side.
>
> This has these advantages over Winning Votes: it appears to meet the
> "Approval Bad Example"
> defection-related criterion, it can't fail to elect a positionally
> dominant Smith-set member, and it
> doesn't have any zero-info random-fill incentive.
>
> Instead, in the "acceptables versus unacceptables" situation it has the
> more natural zero-info
> strategy of just equal-top ranking the acceptables and truncating the
> unacceptables.
>
> It doesn't share Winning Votes' compliance with Minimal Defense
>  (incompatible, or effectively so,
> with ABE compliance).
>
> It has these advantages over Margins: it meets the Plurality criterion and
> it meets Steve Eppley's old
> "Non-Drastic Defense"  criterion.
>
> That says that if  more than half the voters rank X above Y and X no lower
> than equal top, then Y
> can't win.
>
> 46: A>C ("sincere" may be A>B)
> 10: B>A
> 10: B>C
> 34: C=B ("sincere" may be C>B)
>
> More than half the voters rank B above A and B no lower than equal-top,
> but Margins elects A.
> If the method were Bucklin, B would be the only candidate with a majority
> score in the first round.
>
> Using the rules of my suggested method, the pairwise comparisons go:
>
>  B>A 54>46,    A>C 56-44,    C>B 80-54  (the 34 C=B have been added to
> both sides).
>
> The weakest defeat (as measured by Losing Votes) is B's, so B wins. Or in
> terms of Ranked Pairs,
> the strongest pairwise result is A>C so that is locked and the next
> strongest is B>A so that is locked
> and then C>B is skipped because it's incompatible with an already locked
> result; so the final order is
> B>A>C.
>
> Enough for the time being.
>
> Chris Benham
>
>
>
>
>
> ----
> Election-Methods mailing list - see http://electorama.com/em for list info
>
>
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