Thank you Brian for doing this. Looks like Leno is the legit winner and STV and Condorcet agree.
However, the Leno-Breed pair wise tally in the defeat matrix should be exactly the same as the STV final round result. So something is wrong somewhere.
But thanks for doing this. I was about to code up a MATLAB program to parse and count this thing.
--r b-j           ***@audioimagination.com
"Imagination is more important than knowledge."
-------- Original message --------
From: Brian Olson <***@bolson.org>
Date: 6/10/2018 7:46 AM (GMT-08:00)
To: EM <election-***@lists.electorama.com>
Subject: Re: [EM] RCV in SF Mayoral election
Ok, a few lines of Python poking the raw data shows I must have some bug in my Condorcet implementation. Digging into that...
On Sun, Jun 10, 2018 at 10:08 AM, Greg Dennis <***@voterchoicema.org> wrote:
Brian, how is it possible that those differ? Since all the other candidates are eliminated in the final round, shouldn't that necessarily be the same as the pairwise contest between those two?
On Sun, Jun 10, 2018, 9:46 AM Brian Olson <***@bolson.org> wrote:
I processed the latest data (2018-06-09) and posted the results of the SF Mayor election using a few algorithms:https://bolson.org/~bolson/2018/SF_Mayor_20180605.html
The Condorcet win is now 97436 to 91740 for Leno over Breed.The IRV final round is still just 94783 to 94393.
I'm using my software posted at https://github.com/brianolson/voteutil
commands (needs maven installed for compiling Java, and needs Python3):
curl -O http://www.sfelections.org/results/20180605/data/20180609/20180609_ballotimage.txtcurl -O http://www.sfelections.org/results/20180605/data/20180609/20180609_masterlookup.txt
(mkdir -p ~/psrc && cd ~/psrc && git clone https://github.com/brianolson/voteutil.git && cd ~/psrc/voteutil/java && mvn package)python3 ~/psrc/voteutil/python/rcvToNameEq.py -m 20180609_masterlookup.txt -b 20180609_ballotimage.txt -o 20180609_%s.nameqjava -jar ~/psrc/voteutil/java/target/voteutil-1.0.0.jar --rankings --full-html --explain -i 20180609_Mayor.nameq >/tmp/a.html
On Sat, Jun 9, 2018 at 9:33 PM, Greg Dennis <***@voterchoicema.org> wrote:
I quickly looked at the vote data and saw that lots of ballots are categorized as "Exhausted by Over Votes" and "Under Votes," but there is no data indicating exactly how those ballots were marked, so we lack enough information to be sure of final results.
Actually, all the data you need is available from that page. The "Ballot Image" file will give you the full cast vote record of every individual ballot, and the "Master Lookup" is the legend that tells you what each number means. If you have trouble interpreting the numbers, just ping me!
Post by Greg Dennishttps://sfelections.sfgov.org/june-5-2018-election-results-detailed-reports
I quickly looked at the vote data and saw that lots of ballots are categorized as "Exhausted by Over Votes" and "Under Votes," but there is no data indicating exactly how those ballots were marked, so we lack enough information to be sure of final results.
Converting instant-runoff counts into pairwise counts might be (probably is?) possible, but I don't have time to do that analysis.
Post by Greg DennisThe 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.
Yes, circular ambiguity -- in which there is no Condorcet winner -- is rare when the number of ballots exceeds a few hundred.
Post by Greg DennisOn Sat, Jun 9, 2018 at 2:07 AM, robert bristow-johnson
   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.
Based on a very quick guesstimate it looks like about 30 or so ballots had this issue. Right?
That's not a big number, but a fair counting method -- such as pairwise counting -- would not have to discard any ballots.
The bigger number is "under votes" and admittedly pairwise counting cannot compensate for a voter saying "here is the only acceptable choice" (or two choices in this case).
It's great that these results are getting analyzed by people who do not drink the FairVote kool-aid.
In haste,
Richard Fobes
"The VoteFair guy"
On 6/9/2018 6:25 AM, Greg Dennis wrote:
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
<***@audioimagination.com <mailto:***@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 âThis is the system we are working with. Thatâs
  > > a discussion we can have at a later time. For now, weâre stuck
  with it.â
  > > - 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 peopleâs 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 wonât 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 Breedâs response to being
  asked if
  >> RCV is fair? She stated âThis is the system we are working with.
  Thatâs
  >> a discussion we can have at a later time. For now, weâre stuck
  with it.â
  >> - 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,
  >> âChris
  >>
  >>
  >>
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  r b-j             ***@audioimagination.com
  <mailto:***@audioimagination.com>
  "Imagination is more important than knowledge."
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