[EM] Burlington VT reconsidering IRV 10 years after IRV failed to elect the Condorcet Winner

[robert bristow-johnson]

> On December 8, 2019 11:24 AM Markus Schulze <markus.schulze8 at gmail.com> wrote:
> 
>  
> Hallo,
> 
> Toby Pereira wrote:
> 
>  > I know I'm going a bit off-topic, but what
>  > is the estimated probability that Schulze and
>  > Ranked Pairs would give a different result in
>  > a real-life election? I'd be surprised if it
>  > was more than about 1 in 10,000, and where
>  > there was a different winner between them,
>  > neither winner would be so much obviously the
>  > "right" winner that it would cause protests
>  > in the streets if the other one were to win.
> 
> The Schulze winner is almost always identical
> to the MinMax winner, while the Tideman winner
> differs from the MinMax winner needlessly
> frequently.

but it's no different result from RP or Schulze (both based on margins) for a cycle of 3 candidates (the Rock-Paper-Scissors situation).  and, of course they all agree when there is a Condorcet winner.  how often do you expect a ranked-ballot election to result in a cycle with a Smith set larger than 3?  i might expect the odds to be virtually astronomically small if it were a governmental election.  this is why i advocate Condorcet-compliant language that is as flat (treats all situations consistently) and simple to describe for legislative language.  i can describe MinMax and RP in English.  i know that Markus sent me a very concise (but not understandable for the laity) legal language for enacting Schulze, but i just didn't think it would be seen as simple and clear enough for voters to understand and trust how their elections are carried out and the results returned.  this is a very difficult political hurdle even for IRV RCV.


> Norman Petry's calculations:
> https://groups.yahoo.com/neo/groups/election-methods-list/conversations/topics/5948
> http://lists.electorama.com/pipermail/election-methods-electorama.com/2000-November/069868.html
> 
> Jobst Heitzig's calculations:
> https://groups.yahoo.com/neo/groups/election-methods-list/conversations/topics/14251
> http://lists.electorama.com/pipermail/election-methods-electorama.com/2004-May/078166.html
> 
> Barry Wright's calculations (section 8):
> https://services.math.duke.edu/~bray/Courses/49s/Senior%20Theses/Barry%20Wright/Barry%20Wright's%20Thesis.pdf
> http://www.professorbray.net/Service/Theses/Wright.pdf
 
i should probably look them up, but are these statistical studies?  like with simulations?


> This means that, in those cases where the
> Schulze winner differs from the Tideman winner,
> the worst pairwise defeat of the Tideman winner
> usually is worse than the worst pairwise defeat
> of the Schulze winner.

but this gotta be for Smith set greater than 3 candidates, right?  they gotta have the same results for a CW or Smith set of 3, right?

> In my opinion, this is
> an advantage for the Schulze method because the
> worse the worst pairwise defeat of the winner
> is the more difficult it is to justify the
> election result without having to go into
> the details of the counting process.
> 
> I also believe that the fact, that the
> MinMax method satisfies mono-add-top and
> mono-remove-bottom, and the fact, that the
> Schulze winner is almost always identical to
> the MinMax winner, together mean that the
> Schulze method violates mono-add-top or
> mono-remove-bottom less frequently than
> the Tideman method.

Markus, i am convinced that, technically, Schulze would be best.  but i see the political problem of election reform differently.  i am not gonna "let the perfect be the enemy of the good."  if we can get IRV over FPTP, i will hold my nose and vote for IRV.  if we can get Condorcet-compliant RCV enacted (even if it's BTR-STV), i will celebrate.  i don't ever expect to see a cycle occur in an RCV election for government office in my lifetime.  admittedly, before 2009, i had never expected to see an IRV elect someone other than the CW, but that single event convinced me that Burlington should not restore exactly the same failed IRV method.  i think this BTR-STV has some hope of becoming law.  i'll find out a little more about how much hope tomorrow at the Charter Change Committee meeting (it will be early Tuesday morning for your timezone).  i'll report to you guys how well it goes.

right now, the working language for the Charter change is: 
________________________________________________________

§ 5 Election to be by ballot; method of election:

All elections of mayor, city councilors and school commissioners shall be by ballot, using a system of ranked choice voting without a separate runoff election. The chief administrative officer shall implement a ranked choice voting protocol according to these guidelines:
     (1) The ballot shall give voters the option of ranking candidates in order of preference.
     (2) If a candidate receives a majority (over 50 percent) of first preferences, that candidate is elected.
     (3) If no candidate receives a majority of first preferences, an instant runoff re-tabulation shall be performed by the presiding election officer. The instant runoff re-tabulation shall be conducted in rounds. In each round, each voter’s ballot shall count as a single vote for whichever continuing candidate the voter has ranked highest. The candidate with the fewest votes after each round shall be eliminated until only two candidates remain, with the candidate then receiving the greatest number of votes being elected.
     (4) The city council may adopt additional regulations consistent with this subsection to implement these standards.
________________________________________________________


and my suggested revision is:
________________________________________________________

§ 5 Election to be by ballot; method of election:

All elections of mayor, city councilors and school commissioners shall be by ballot, using a system of ranked choice voting without a separate runoff election. The chief administrative officer shall implement a ranked choice voting protocol according to these guidelines:
        (1) The ballot shall give voters the option of ranking candidates in order of preference. Equal ranking of candidates shall not be allowed and every unranked candidate shall be considered to be ranked lower than every ranked candidate.
        (2) If a candidate receives a majority (over 50 percent) of first preferences, that candidate is elected.
        (3) If no candidate receives a majority of first preferences, an instant runoff re-tabulation shall be performed by the presiding election officer. The instant runoff re-tabulation shall be conducted in sequential rounds. A "remaining candidate" is defined as a candidate that has not been eliminated in any previous round. Initially, no candidate is eliminated and all candidates begin as remaining candidates.
        (4) In each round, each voter’s ballot shall count as a single vote for whichever remaining candidate the voter has ranked highest. The two candidates with the fewest votes in a round, herein designated as "A" and "B", shall be compared in a runoff in which the candidate, A or B, with lesser voter support is eliminated in the current round. If the number of ballots having A ranked higher than B exceeds the number of ballots having B ranked higher than A, then B has lesser voter support, B is eliminated, and A remains for the following round. Likewise, if the number of ballots having B ranked higher than A exceeds the number of ballots having A ranked higher than B, then A has lesser voter support, A is eliminated, and B remains for the following round. In the case that the aforementioned measure of voter support between A and B is tied, then the candidate with fewest votes is eliminated in the current round.
        (5) This runoff re-tabulation, eliminating one candidate each round, is repeated until only two candidates remain, with the candidate then receiving the greatest number of votes being elected.
        (6) The city council may adopt additional regulations consistent with this subsection to implement these standards.
________________________________________________________


I sent it to the city attorney to solicit her help in identifying and correcting language that real lawyers would consider insufficiently legalistic.  It doesn't deal with ties of votes, but neither does the original language proposed by the Progs.


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"Imagination is more important than knowledge."