[EM] RCV in SF Mayoral election

Greg Dennis greg.dennis at voterchoicema.org
Sat Jun 9 06:25:36 PDT 2018


San Francisco always make the cast vote record public:
https://sfelections.sfgov.org/june-5-2018-election-results-detailed-reports

Based on the most recent analysis of these numbers that I saw, Leno was
indeed the Condorcet winner, and if Breed were to beat Leno in the final
round, she would then necessarily be the Condorcet winner. The probability
of IRV not elected the Condorcet winner appears to be exceedingly low in
practice. We're up to about ~200 IRV elections conducted nationwide since
2004 and Burlington 2009 is the only case so far.

On Sat, Jun 9, 2018 at 2:07 AM, robert bristow-johnson <
rbj at audioimagination.com> wrote:

>
> Richard, a few points:
>
> the limitation to only three levels of ranking is a problem.  if someone
> ranked all three levels and none of the candidates ranked were either
> London Breed nor Mark Leno, that voter was effectively "disenfranchised" by
> being unable to weigh in on the final choice of choosing the mayor.
> however, i think the news media made it clear that the race was really
> gonna be between Leno, Breed, and Kim, so these fringe voters might have a
> chance to insincerely mark either Leno or Breed as their 3rd choice and
> betray their *true* third choice and, in doing so, have an effect in the
> final round.
>
> ignoring the problem of only 3 ranking levels, it is not possible that
> London Breed is the Condorcet Winner (a.k.a. "pairwise champion").  it
> might be the case that Mark Leno or Jane Kim is the Condorcet Winner and if
> the latter is the case, this is another real indictment against STV or IRV
> as a method of tallying RCV.  and your reverse namesake, FairVote, is
> partially (or mostly) to blame.
>
> i wonder if the City of SF has a file of all of the cast and scanned
> ballots and the full ranking for each.  if so, and if they release it to
> the public, we can investigate if there is a Condorcet Winner and if that
> CW is or is not Mark Leno.  this would be interesting.
>
> L8r,
>
>
>
> r b-j
>
>
> > On 6/8/2018 6:24 PM, Christopher Colosi wrote:
> > > ... She stated “This is the system we are working with. That’s
> > > a discussion we can have at a later time. For now, we’re stuck with
> it.”
> > > - insinuating it is not fair. I was quite bothered to have a Dem in a
> > > progressive city insinuate that first past the post is more fair. ...
> >
> > This remark does not imply support for first past the post (FPTP, a.k.a
> > plurality counting).
> >
> > There are other ways to count the preference marks on "ranked-choice"
> > ballots. In particular, pairwise counting could be used instead of
> > instant-runoff counting, and that is fairer than FPTP.
> >
> > > 1. May not elect majority candidate
> > > ...
> > > Is this common? This is
> > > probably an abnormally close race. Thoughts?
> >
> > I doubt the voters would regard this as a close race if they had been
> > able to fully rank all the choices. The 3-choice limitation is
> > simplistic, and complicates the counting.
> >
> > Pairwise counting does not result in any exhausted ballots. Unmarked
> > choices are an indication that the choices are equally disliked. And
> > multiple candidates being marked at the same preference level is also no
> > problem.
> >
> > In other words, the ballots contain enough information that they can be
> > counted in other ways, besides instant-runoff counting. Those alternate
> > counting methods could reveal a clearer outcome.
> >
> > In haste,
> > Richard Fobes
> >
> >
> > On 6/8/2018 6:24 PM, Christopher Colosi wrote:
> >> Curious to hear people’s thoughts on some issues.
> >>
> >> 1. May not elect majority candidate
> >> In SF, we restrict to 3 choices to simplify the process. As the vote
> >> currently stands, 144 votes separate the top two candidates (<0.1%) and
> >> over 16,000 ballots have been exhausted (all 3 choices eliminated).
> >> About 9% of voters have been removed from the pool. It is very possible
> >> that the result would have shifted if they had the opportunity to rank a
> >> 4th candidate, and therefore, it is possible that we won’t elect the
> >> person who truly represents the majority. Is this common? This is
> >> probably an abnormally close race. Thoughts?
> >>
> >> 2. What are your thoughts on London Breed’s response to being asked if
> >> RCV is fair? She stated “This is the system we are working with. That’s
> >> a discussion we can have at a later time. For now, we’re stuck with it.”
> >> - insinuating it is not fair. I was quite bothered to have a Dem in a
> >> progressive city insinuate that first past the post is more fair. It
> >> also felt divisive. If Leno wins, will her supporters feel that
> >> democracy prevailed, or that the election was stolen? She also presents
> >> herself as a minority candidate and it is my understanding that RCV
> >> gives minority candidates better chances and causes all candidates to be
> >> more likely to campaign to minority communities. Am I mistaken? Are
> >> there any legitimate arguments that FPTP can be more fair? Thoughts?
> >>
> >> Regards,
> >> —Chris
> >>
> >>
> >>
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>
> --
>
> r b-j                         rbj at audioimagination.com
>
> "Imagination is more important than knowledge."
>
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> Election-Methods mailing list - see http://electorama.com/em for list info
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>


-- 
*Greg Dennis, Ph.D. :: Policy Director*
Voter Choice Massachusetts

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