[EM] eliminate the plurality loser until there is a Condorcet winner

[robert bristow-johnson]

On May 11, 2011, at 3:51 PM, fsimmons at pcc.edu wrote:

>
> James Green-Armytage asked
>
> Quick question for everyone: Do you happen to know when the method
> described in the subject line (eliminate the plurality loser until
> there is a Condorcet winner) was first proposed?

by Plurality Loser, do you mean the candidate who was ranked 1st the  
fewest times or the candidate ranked last the most times (all who are  
unranked are tied for last place)?

i made mention of either in a paper i wrote in 2009 ("The Failure of  
Instant Runoff Voting to accomplish the very purposes for which it was  
adopted: An object lesson in Burlington Vermont") right after i  
figgered out that the Condorcet winner was not the same as the IRV  
winner (and happened to be the candidate i supported).

i would think that this would have preceded by anyone thinking about  
Condorcet cycle for a minute.

> Forest's attempt at an answer:
>
> I don't know about "first proposed," but I know that we considered  
> it in passing
> when we came up with the DMC proposal, one of whose many  
> formulations is to
> eliminate the approval loser (or candidate ranked on the fewest  
> number of
> ballots) until there is a Condorcet Winner.
>
> We settled on Approval instead of Plurality as the basis for  
> elimination because
> it seemed a lot better at the time. It turns out that DMC is  
> monotonic, for
> example, while the Plurality based method is not.
>
> Long before that (about ten years ago) I suggested a lot of  
> different tweaks on
> IRV that would make it Condorcet compliant in an attempt to show IRV  
> supporters
> how easy it would be to keep IRV from discarding the "true majority  
> winner."

i was impressed with the bottom-two runoff (BTR) in that it's such a  
small change to the existing IRV method used in a few places (and used  
to be in my place).

but i've been thinking that, while BTR or some other Condorcet  
compliant IRV is better than a Condorcet non-compliant IRV, it's still  
IRV and the actual method of tabulation does not allow for precinct  
summability.  if you demand precinct summability (for reasons of  
transparency in elections), then it really has to be a simple  
Condorcet method where you count pairwise tallies locally, post  
publicly and transmit upward the pairwise subtotals.  the election  
should be decided solely by the totals from the pairwise subtotals.   
if Ranked Pairs or Schulze is used, the difference between totals of a  
pair of candidates, the "defeat strength", is part of the decision,  
but it is a derived value from the pairwise totals.

> Mike Ossipoff advised me to forget it, because (having been rebuffed  
> himself
> after proposing all of these ideas and more) he had found out by sad  
> experience
> that the hard core IRV supporters were too closed minded

i *know* i loosened a few IRV supporters here in Burlington.  but,  
unfortunately, the "Keep Voting Simple" side that brought us back to  
Plurality and Delayed Runoff believe that God herself has ordained the  
vote-for-only-one ballot.  we won't be revisiting anything with a  
ranked ballot again in my lifetime.  i hope i'm wrong about that.

> to even consider
> anything other than pure Hare/STV/AV/IRV.  Since that time I have  
> found a few
> staunch IRV supporters that are willing to think about other  
> possibilities, but
> on the whole Mike seems to have been right.

well, when a few more towns toss out IRV, i hope that FairVote gets  
the message and starts promoting other tabulation methods than STV  
with the ranked ballot.  what makes me so mad is that Burlington  
people that are IRV supporters (because they are election reform  
people and do not believe in the two-party religion), these people had  
no idea that there was another way to look at those very same  
ballots.  Fairvote essentially sold ranked-choice voting with IRV as  
if they were the same thing.  as if there *is* no ranked-choice voting  
without IRV.

--

r b-j                  rbj at audioimagination.com

"Imagination is more important than knowledge."