Re:What is ranked-choice voting and why is New York using it?
by elihu on Wednesday June 23, 2021 @12:52AM
(#27600916)
You're right that Borda count on its own isn't a great system. Though an RCV-style system that eliminates candidates on the basis of least-Borda count would be something else. It might be better than either normal IRV or plain Borda count on their own. (Though I still think I'd rather go with approval voting or STAR.)
Re:What is ranked-choice voting and why is New York using it?
by vitus on Wednesday June 23, 2021 @07:39AM
(#27603287)
It sounds like you're referring to
https://en.wikipedia.org/wiki/Nanson%27s_method
and the related Baldwin's method, which, while being Condorcet methods, both fail monotonicity.
Re:What is ranked-choice voting and why is New York using it?
by elihu on Wednesday June 23, 2021 @06:09PM
(#27611141)
I looks like what I was thinking of is Baldwin's method, actually. Failing monotonicity is still a problem, but it's actually pretty cool that it satisfies the Condorcet criterion. That seems like a pretty big step up from plain IRV.
> I've wondered if IRV couldn't be substantially improved by using ... rather than eliminating the candidate with the least first-choice options.
This is exactly the family of RCV systems -- IRV merely defines one implementation by which a winner is selected from a ranked ballot.
Borda count has its own pathologies, too -- the usual cited problem is that it fails independence of irrelevant alternatives.
https://en.wikipedia.org/wiki/Independence_of_irrelevant_alt...
(Further, Borda count fails the majority criterion, namely there are situations where a candidate is the first pick of a majority of the electorate, yet fails to win. Some proponents of Borda count argue this is a feature, not a bug.)
The wiki article for Borda count has a solid table of various voting systems and whether they satisfy various criteria:
https://en.wikipedia.org/wiki/Borda_count#Other_properties