[EM] So I got an email...

[Richard Lung]

As recently written in my Winners or representation thread, I don't think the failure to achieve a Condorcet winner, as in Burlington justifies calling the preference voting system used, a mistake. It is an adverse consideration but not a definitive mistake. And as a 1 in 135 occurence, it is not highly significant -- not significant enough, in my opinion, to justify over-loading RCV with a CW veto on the result. I might compare it to leaving the scaffold on a building as a permanent feature.

RCV could be improved. -- I invented such a system, Binomial STV that works in single districts as well as multi-member districts (tho single districts do not work nearly as well as  [STV] multi-member districts). However I would not dream of employing an improved system (BinomialSTV) without test elections, which I would naturally like it to receive, before official employment.

Regards,
Richard Lung. 


On 10 Apr 2022, at 2:49 am, robert bristow-johnson <rbj at audioimagination.com> wrote:

... from Rob Richie.  I am trying to be nice (because I'm in the last throes of my struggle to keep Vermont from repeating a mistake) and I saw a small numerical error in the FV page at https://www.fairvote.org/research_rcvwinners  regarding non-monotonicity (and Burlington 2009).  So I wrote him (the first time since 2017) and he wrote back.  That's a lot better than I can say for Aaron Hamlin.

Anyway, in our friendly back-and-forth, Rob brought up a contrived example of an election where they purport that Hare works better than Condorcet.  In this rhetorical example there is a dead-tie symmetry.  And Rob suggested that it gets resolved with "RCV - Jump ball" or "jump ballot".  What, exactly, is "jump ballot"?  Is it drawing a ballot out of the entire pile at random?  Like sortition?

FYI This is the context:

___________________________


A and B, polarizing candidates
C is Condorcet candidate in third

1st choices
A - 40%
B - 40%
C - 20%

Preferences (honest)
ACB - 40%
BCA - 40%
CAB - 10%
CBA - 10%

RCV - Jump ball
Condorcet - C wins 60%-40% over both A and B

BUT... polls show this to be the case, and backers of A and B both know the only way they can win is to keep C out of it. So their backers bury C

Preferences (strategic, both major campaigns)
ABC - 40%
BAC - 40%
CAB - 10%
CBA - 10%

C is no longer the condorcet winner, as both A and B seem to defeat C by 8-020.  The winner will be decided by a jump ballot tally between A and B. Strategy worked

Let's suppose only one side decides to do this. It probably backfires, but still gives them a chance depending on the tiebreaker., So you might get:

Preferences (strategic, only 1 major campaign - backers of B)
ACB - 40%
BAC - 40%
CAB - 10%
CBA - 10%

Condorcet:  C over B 60-40  but A over C 80-20 and jump ball with A and B. So B voters may end up helping A win if they lose the jump ballot, they create a cycle and then win an IRV tiebreaker if they win the tiebreaker between A and B.

___________________________


I don't mind hearing opinions from anyone on the list about this scenario, but what I most want is a good understanding of exactly what Rob means by "jump ballot".  (And I know I could ask him, but I wanna ask you dawgs instead.)

I told Rob about my paper about Burlington 2009. https://tinyurl.com/2tety9tj  I dunno if that was a mistake or not.

About my struggle in Vermont: I have gotten the attention of several legislators in Vermont.  Several RCV bills have stalled and languished in committee and will die when this legislative session ends at year's end.  But the Burlington RCV charter change has been revived and has passed the Vermont House (but they took out the specific language of exactly how the RCV election method will work, bumping that back to Burlington city council).  It's going before the Vermont Senate Government Operations Committee in the near future and I expect to be visiting the state capitol again to lobby.

I thank y'all.

robert
--

r b-j . _ . _ . _ . _ rbj at audioimagination.com

"Imagination is more important than knowledge."

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