Bottom Two Runoff (Condorcet IRV hybrid)
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@rb-j said in Bottom Two Runoff (Condorcet IRV hybrid):
If you want results to be consistent with the City Clerk's report,
Cool thanks I'll do that.
@jack-waugh said in Bottom Two Runoff (Condorcet IRV hybrid):
It will help if it isn't using higher precision integers or floats than what can be represented in IEEE floating point
I can't imagine floating point precision making a difference unless you are doing something really weird. I prefer avoid all floating point math in tabulation methods, or at the least define them in ways that floating point math isn't necessary. (javascript uses floating point even for operations that could be pure integer, such as counting, but I can't remember where it has ever been a problem in anything I've done except when converting a number to a human readable string)
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I have to say I am intrigued with the idea of marketing IRV Bottom-two Runoff. If it weren't for marketing concerns, I would want to perturb it further to make it balanced and pairwise additive, but that would throw away the possibility of getting IRV-Hare enthusiasts to accept it.
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@jack-waugh said in Bottom Two Runoff (Condorcet IRV hybrid):
I have to say I am intrigued with the idea of marketing IRV Bottom-two Runoff.
Awesome. Maybe all the time I've spent on this forum in the past week hasn't been entirely wasted.
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@rob, you said you think that whether equal ranking is permitted is an "implementation detail". But I wouldn't be surprised if RCV IRV Hare enthusiasts were to refuse to allow equal ranking. Anyway, they are refusing bottom-two runoff even without equal ranking, as the tweet I cite above argues against it and comes from whoever controls the Twitter account "fairvote".
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@jack-waugh I'm saying that, if equal ranking is allowed, it doesn't make it a different method. It is just one variation of the same method. Note that the Electowiki page for IRV mentions the possibility of equal ranking, and here is a (very short) discussion of equal rank IRV: https://www.reddit.com/r/EndFPTP/comments/dgzf5k/what_are_the_shortcomings_of_equalrank_irv/
I'm not speaking of the practical issue of whether Fairvote or RCV IRV Hare enthusiasts will allow it, whether voting machines can deal with it, whether it is allowed under some specific legislation, etc. That's a different issue.
I imagine the best way to handle equal rankings would be to count fractional votes. (I will need to implement it so I can process cardinal ballots as IRV-Hare and IRV-BTR)
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Untested, draft code for tallying RCV-IRV-B2R: tally.mjs
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@rob said in Bottom Two Runoff (Condorcet IRV hybrid):
I will need to implement it so I can process cardinal ballots as IRV-Hare and IRV-BTR
naive_strict_ranking.mjs is an untested draft for converting affinities (same form as so-called "cardinal" ballots) into ranking ballots. The assumption underlying my design of the code is that equal-ranking is forbidden except for the sludge at the bottom.
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For simulations and small elections in particular, it's in my opinion important to understand the corner cases that can arise in Bottom-Two Runoff, and decide how the outcome should be determined. One reason to think this way is to make sure that the tallying algorithm is deterministic. A deterministic algorithm will make all experiments repeatable, that are based on applying the algorithm to a given set of example data.
I posted an algorithm or two in here, but it or they were wrong.
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I have advanced the code from where it was crashing every time to where it gives wrong answers, so that's progress.
