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

Kristofer Munsterhjelm km_elmet at t-online.de
Fri Dec 6 15:22:30 PST 2019

On 06/12/2019 13.48, fdpk69p6uq at snkmail.com wrote:

> Has BTR-STV been used in the real world or analyzed academically?  There
> are only two sentences about it on Electowiki.

Warren has written a bit about it here: https://rangevoting.org/BtrIrv.html

(He states that every Condorcet method fails mono-add-top, which I don't
think is true, but his example does show that BTR-IRV fails mono-add-top.)

On a funny note, a dance contest program on TV here uses a judging
method that could be seen as a variant of BTR-IRV (if you're willing to
be very generous). It works like this:

At the end of each program, the judges provide their rating of the
contestants, and then the callers provide their rating by number of
calls and web votes. Those are combined to produce an overall rating,
and then the two bottom contestants do a repetition of their dances,
during which the callers vote on who gets to continue on to the next
program and who is eliminated.

It's "like" BTR-IRV since there's a ranking, and the bottom two are
subject to a runoff, and the loser of the runoff is eliminated. But it's
a real runoff (not instant), and the initial "round" (program)'s ranking
is based on ratings, not on first preferences.

I don't think BTR-IRV has been used in public elections anywhere, unlike
Borda-elimination (as you point out below).

> I know Nanson/Baldwin methods have both going for them, and they're
> Condorcet and relatively simple to explain to someone familiar with IRV:
> "Instead of eliminating the candidate with the least number of
> first-preference votes (which results in vote-splitting and discards
> some voters' preferences), you eliminate the candidate with the worst
> average ranking."
> "In contrast to the Borda rule, our experiments with Baldwin’s and
> Nanson’s rules demonstrate that both of them are often more difficult to
> manipulate in practice. These results suggest that elimination style
> voting rules deserve further
> study." http://dx.doi.org/10.1016/j.artint.2014.07.005

James Green-Armytage's paper on strategic resistance seems to put
Nanson/Baldwin around the same manipulability level as Minmax.
http://jamesgreenarmytage.com/strategy-utility.pdf page 18.

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