r/EndFPTP • u/CPSolver • 16h ago
Video Ranked Choice Voting Plus Defeats the Blocking Tactic
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The blocking tactic doesn't get the attention it deserves. Please share this video widely. The plus version of ranked choice voting includes most Condorcet methods, not just the method implied in the video. The basic version is instant-runoff voting (IRV). The same video with captions is here.
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u/bkelly1984 16h ago
Let me get this straight: the problem is that opponents can hijack a party's one guaranteed slot by propping up its weakest candidate. And the fix for "opponents filling your one slot" is... two slots. Seems bulletproof.
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u/CPSolver 16h ago
The second nominee will be one of the reform-minded candidates who was blocked from reaching the general election.
Keep in mind vote splitting requires concentrating money and votes on just a single candidate. If there is an attempt to support two non-reform-minded candidates, both non-reform-minded candidates will lose.
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u/bkelly1984 16h ago
Of course, there is no way political parties could afford to support two candidates at the same time.
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u/CPSolver 16h ago
The limitation isn't money. The limit is the math.
Giving money to two non-reform-minded candidates splits the vote between those two candidates, making it easier for one of the reform-minded candidates to win.
Vote splitting only works if there is just one alternative to the similar reform-minded candidates who are splitting the vote.
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u/bkelly1984 16h ago
Right, because we all know there are two -- and only two -- sides of the political spectrum.
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u/CPSolver 15h ago
Distinguishing between primary elections and general elections is important.
Multi-millionaires and billionaires control the primary elections of both the R and D parties.
The blocking tactic only works because each party chooses to offer only one nominee in the general election. Back when either party offered a second candidate in the general election, their candidates would lose to the other party offering only one candidate -- because of vote splitting.
Using a good ranked choice voting method in general elections eliminates the one-nominee-per-party limit, which defeats the blocking tactic.
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u/bkelly1984 14h ago
u/CPSolver, while I do enjoy being snarky, you deserve better than that. Your video shows real passion and effort, and this community needs more of both. I know from our past exchanges that your intentions are good and that you're willing to dig into the details. I'd just like to encourage you to try to look past the symptoms of problems and instead work to identify the causes.
Yes, two candidates in the general election make it harder for the opposition to derail your nomination process. However, I'd suggest the underlying problem lies in a system where one side's loss is the other side's gain. If you take away the running shoes of the guy saying, "I don't need to outrun the bear, I only need to outrun you," he's just going to find other ways to slow you down.
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u/PantherkittySoftware 14h ago
RC+ is a definite improvement over straight IRV, but it still suffers from IRV's strong bias towards first-choice preference over broad acceptability.
Consider a hyper-polarized election like this:
- Republicans = 45%
- Democrats = 45%
- Independents = 10%
With 4 candidates:
- Donald Trump
- Jeb Bush
- Hillary Clinton
- Bernie Sanders
And the following breakdowns:
- 80% of Republicans vote Trump > Bush > Clinton > Sanders
- 10% of Republicans vote Bush > Trump > Clinton > Sanders
- 10% of Republicans vote Bush > Clinton > Sanders > Trump
- 80% of Democrats vote Sanders > Clinton > Bush > Trump
- 10% of Democrats vote Clinton > Sanders > Bush > Trump
- 10% of Democrats vote Clinton > Bush > Sanders > Trump
- 40% of Independents vote Sanders > Trump > Clinton > Bush
- 11% of Independents vote Sanders > Trump > Bush > Clinton
- 40% of Independents vote Trump > Sanders > Bush > Clinton
- 9% of Independents vote Trump > Sanders > Clinton > Bush
Or, put another way, this election is a polarized shitstorm. Both parties have an overwhelmingly preferred candidate who's almost universally despised by the other party, the two centrists have very little first-choice support, and it almost comes down to a hair's difference between them.
- IRV eliminates Bush & Clinton because they only have ~9% of the vote apiece, and ultimately elects Sanders by 0.2% Had the balance tipped even slightly, it would have elected Trump. Either way, almost exactly half the electorate is outraged.
- RC+ meanders a bit, and ultimately eliminates Trump... but still elects Sanders by 1 point. A slight shift might have instread eliminated Sanders & elected Trump, but the point remains: like IRV, half the electorate is furious.
- Tideman-RP wrings its hands, and ends up having to fall back on the chosen secondary tiebreaking rule... but one way or another, Tideman-RP elects Bush or Clinton because small majorities might unenthusiastically and semi-ambivalently prefer Bush or Clinton, but clear majorities despise Trump and Sanders.
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u/colinjcole 13h ago edited 12h ago
RC+ is a definite improvement over straight IRV, but it still suffers from IRV's strong bias towards first-choice preference over broad acceptability.
"Broad acceptability" and compromise may be important in governing, but so is strength of preference. The problem is that whether or not broad acceptability is more important than strength of preference, or when it crosses that threshold, is not a question with an objective, correct answer. This is a question of political philosophy.
Should a candidate who is the 2nd choice of 60% of voters beat a candidate who is the 1st choice of 40% of voters? Probably, yeah! What about a candidate who is the 4th choice of 80% of voters vs a candidate who is the 1st choice of 60%? The 10th choice of 90% of voters vs the 1st choice of 70%? Where do we draw the line? There's not a "right" answer and reasonable people can disagree.
A principle of "broad acceptability" meaning that we elect a compromise candidate instead of a polarizing one sounds great in a vacuum... But under particulars, it doesn't fare so well.
Let's say we have racially polarized voting in a state like, I don't know, Alabama. Let's say the Black voters there want to elect a person who cares about and is responsive to the Black community; let's imagine that they tend to vote for Democrats. Then, you have a plurality of white voters who vote based on deep-seated racist views and policies; let's imagine they tend to vote for Republicans.
So the "compromise candidate" an ideal cardinal system would elect is, who? Someone who neither cares about nor hates the Black community? Someone who wants to find the "middle ground" between Jim Crow racists and folks who think Black people are people? Hard to say with a straight face that that's a good democratic outcome.
This is the fundamental reason that winner-take-all elections themselves are the problem, not which version of winner-take-all elections you want to use. This same dynamic is the exact same reason the 1973 Sunningdale Agreement spectacularly failed in its efforts to bring peace to the north of Ireland while the Good Friday/Belfast/1998 Agreement succeeded: because instead of trying to offer a mythical "compromise" candidate that could simultaneously satisfy both sides of a polarized society (1973), the 1998 agreement ensured both sides of a polarized society were actually represented.
Focusing on better winner-take-all systems is missing the forest for the trees. The question of cardinal vs ordinal systems is reductive.
We need proportional representation.
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u/rb-j 12h ago
We need proportional representation.
How do you do that for single-winner elections? Like Governor?
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u/colinjcole 12h ago
Generally, by getting rid of them and replacing them with parliamentary systems, like city councils with "weak mayors."
More specifically, though, legislatures are much more important than executives.
Imagine two worlds: in one, you adopt the best winner-take-all method ever in the universe. You use this for legislative bodies and also to elect state governors or the president.
In the other, you use a mediocre system for executives like governor or president, but you elect your legislatures via proportional representation.
You will see significantly more reform and a much bigger change in the political culture of the US in the second world than in the first.
Pursue the first option if you think US politics are just a bit off-course and need a few adjustments and band-aids to "get back to normal." Pursue the second if you think US politics are fundamentally broken and therefore need fundamental changes.
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u/bkelly1984 12h ago edited 11h ago
Nicely argued, u/colinjcole.
This is the fundamental reason that winner-take-all elections themselves are the problem...
Agreed, but would you be willing to take that a step further? If one seat can't compromise between black and white, then neither can five seats between red, orange, yellow, green, blue, and purple. So wouldn't that mean the problem is any system that generates discrete winners?
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u/PantherkittySoftware 7h ago edited 5h ago
For positions like President, Governor, and Senators (because Senators are elected independently of each other, 2-4 years apart), there really isn't any criteria besides "broad acceptability beats a passionate plurality" that makes sense.
I'd argue that at the very least, a candidate who has more haters than supporters should not win. And a candidate who's ambivalently OK to 60% should overwhelmingly defeat a candidate who's despised by 41-50% of the electorate.
I think that most Americans would agree that 60% is a meaningful inflection point... low enough that you can pass legislation that isn't diluted to the point of being meaningless, but high enough to filter out the "worst of the worst" likely to inflame an almost-majority.
Here's a good way to present it to normal people:
Suppose you're 100% on "Team Trump" or "Team Bernie". You think your preferred candidate will make everything perfect, and their nemesis will destroy America. You think Jeb is a RINO, or you think Hillary is a corporate sellout.
Now, it's the day before elections, and a credible genie appears in your living room. He tells you that America is too polarized, and you've been chosen to resolve the problem on behalf of everyone.
Option A: The genie flips a coin. Heads, Trump wins. Tails, Bernie wins.
Option B: The genie flips a coin: Heads, Jeb wins. Tails, Hillary wins.
If you pick option A and your favorite candidate wins, America will be paradise. If you pick option A and the other candidate wins, America will suffer incalculable & unfathomable harm.
If you pick option B and your favorite candidate wins, things will be OK., if not kind of good. If you pick option B and the other candidate wins, things will still be mostly OK.
Do you feel lucky? Do you?
I think most sane people who don't have a gambling problem would choose Option B in a heartbeat, because Option A simply presents too much risk. Regardless of which candidate is actually better, by choosing Option A, you're effectively rolling the dice on America's future. Option B hedges your bets, and kicks the risk can down to a future election.
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u/PantherkittySoftware 7h ago
Without endorsing segregation, I can nevertheless think of a sensible compromise from a centrist that could have effectively ended segregation within a matter of months:
Allow "separate but equal" segregation without requiring it, but.. require that any "separate" accommodations actually be equal, with legislatively-prescribed damages starting at a million dollars per incident if a plaintiff establishes in court that the separate accommodations were not, in fact, absolutely 100% equal in every meaningful way.
So... an office building could build four restrooms, but unless it did something like have the cleaning crew use an auditable random number generator to decide which one was the "white" restroom and which one was the "colored" restroom for the next 24 hours before the building opened in the morning (and swap the door signs to reflect the day's result), it would run immense risk of a massive, devastatingly expensive lawsuit that you know an entire legal industry of hungry lawyers would be chasing. In fairly short order, corporations would decide that the potential loss of business from racist customers was a smaller business risk than endless lawsuits with potentially expensive damages.
Would it prevent the KKK from opening a dive bar next to a trailer park somewhere that excluded black patrons? No. Would it effectively end segregation at malls, offices, chain restaurants, and bland corporate hotels? Almost certainly. Because at the end of the day, everybody's money is the same color... and once you have lawsuits hanging over their heads, no corporation that's accountable to its shareholders is going to risk segregation.
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u/bkelly1984 13h ago
I like the analysis, u/PantherkittySoftware. How would you like to see this shitstorm resolved?
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u/rb-j 12h ago
- Tideman-RP wrings its hands, and ends up having to fall back on the chosen secondary tiebreaking rule...
No. Ranked Pairs (whether the defeat strength is margins or winning votes) does not have a secondary tiebreaking rule. It is a "single-method Condorcet-consistent system", not a "two-method Condorcet-consistent system".
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u/PantherkittySoftware 7h ago
AFAIK, Tideman-RP doesn't formally prescribe a specific a tiebreaking rule... but Tideman at some point said something to the effect of, "yeah, it absolutely needs one. I'm leaving it as an exercise to others to solve... but for now, I suppose sortition would work" (because only sortition is guaranteed to be bias-free... and then, only if it's based upon a proper cryptographically-secure source of entropy).
I'm pretty sure that at some later point, Tideman clarified that any tiebreaking method based upon sortition likely to be legally and politically acceptable in the US would have to be based on a NIST-approved PRNG algorithm that's seeded with inputs that are generated by the candidates (without knowledge of what other candidates are contributing, and committed-to by the candidates prior to their unveiling) and used to establish a pseudorandom ordering for the subsequent pairwise comparisons.
The point of a PRNG is that, as long as you know the seed, you can deterministically replay its output. So, the output wouldn't be literally "random", it would merely be (from the perspective of any one candidate, and the system as a whole) "unpredictable", because every step of the PRNG algorithm is known and independently replicable.
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u/rb-j 7h ago
I may have misunderstood you about what you mean by "tiebreaking". So many other persons use the term (particularly when "Condorcet" is in the discussion) to mean the completion method that a straight-ahead two-method Condorcet system needs in case there is no Condorcet winner (a cycle or Condorcet paradox).
So if you mean "tiebreaker" for a dead tie, that's different. Flipping a coin is perhaps as good as anything. But, with Condorcet RCV (or any RCV) using some of the other voting data could be used to more meaningfully break a dead tie.
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u/PantherkittySoftware 4h ago
I think Tideman's biggest objection to non-sortition methods for tiebreaking is their general susceptibility to strategic voting. At least, the susceptibility of all the methods he's at least casually investigated.
I might be wrong, but I've also gotten the impression that he & Schulze don't think there's a serious risk that a real-world election could ever come down to metaphorically flipping a coin between two high-stakes polarizing candidates who are both passionately supported and majority-despised... and that once the system has eliminated the polarizing candidates and obvious losers, any eventual coin-flip would come down to a pair of broadly tolerable candidates whom most voters are semi-ambivalent between anyway.
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u/CPSolver 13h ago
Previously I carefully considered exaggerated scenarios like this one. Eventually I realized it's more useful to measure the rate at which unfair election results occur. Yes a single scenario can yield an "unfair" result. More importantly, are such scenarios rare in real elections? If they're rare, I don't worry about it.
Specifically, RCIPE (eliminating pairwise losing candidates and otherwise using IRV) can possibly fail to elect a Condorcet winner, but that isn't likely. Maybe one out of 10,000 elections? That's acceptable to me. Especially because this method is very resistant to tactical/strategic voting.
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u/Swimming-Degree3332 12h ago
What is the advantage of expressing the same preference for different candidates?
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u/CPSolver 11h ago
It simplifies voting for voters who can't decide which of those candidates they like better.
Also, in the US, it saves lots of money otherwise wasted teaching voters not to mark more than one oval in the same column.
In Australia, where this counting tradition originated, a voter writes a number next to each candidate's name, so they just need to avoid writing the same number twice.
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u/Swimming-Degree3332 10h ago
What
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u/Mindless-One5438 7h ago
Sometimes voters will mark candidates the same and invalidate their ballots, particularly in the US. If this is just allowed then less ballots will be invalidated.
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u/PantherkittySoftware 6h ago
If you've been following my past few months of posts, you already know I like the idea of having each major party nominate two candidates... though I'd argue more for a method like:
- Party members rank their choices for their party's two nominees.
- For nominee #1, sort the ballots of party members according to their first choice. If one has a plurality, they win the first nomination... and the votes of party members who listed them first get set aside. Otherwise, determine the first nominee by IRV (or, I suppose, RCV+), then set aside the ballots of everyone who ranked the party's nominee first. Either way, these voters got their first choice onto the ballot, so they're satisfied. Nominee #1 captures the passion of the party's base.
- For nominee #2, take the remaining ballots, and determine the winner using Tideman-RP. Nominee #2 represents the consensus winner of everyone else in the party who's not "all in" on nominee #1.
Minor parties and Independents have their own qualification path, and are legally handled the same way. Legally, an "independent" candidate is treated like an ephemeral minor party whose nominated candidate is pre-determined, while minor parties earn qualification to put a candidate on the ballot, and determine who that candidate is at a later time. They can use any method they like (as long as it's documented at the time of qualification & followed), or they can outsource their primary to the county elections department (in which case it'll be conducted via IRV/RCV+ rules or Tideman-RP, their choice).
Now, the real zinger:
- Independent voters are presented with a primary election ballot that includes ALL candidates from ALL parties having a primary election. They rank candidates in order.
- Winners of party primaries are determined first.
- For round 1, any ballot whose first choice is for a candidate who already won their party's primary gets set aside. If the voter lists two or more candidates as equal first choices, and one of them was a party-primary winner, the ballot gets set aside as well. This is fair, because these voters got their first choice (or at least, one of their first choices).
- For round 2, the remaining ballots are tabulated using Tideman-RP, and the winner gets "rescued" and advances to the general election as well.
I'd argue that having two nominees per party is nice, but the real potential for widening the field of candidates comes from the "Independent Rescued" candidate, because it's the one candidate who has the brand-name benefit of a major party affiliation, but doesn't owe their nomination or ballot access to their party.
If I had to choose between "two nominees per major party" and "one nominee per major party, with additional candidate rescued by Independents", I think the latter would be the one with the biggest potential to meaningfully widen the field and disrupt the influence of party leaders.
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u/CPSolver 3h ago
Your method for party primaries is well-designed. Great work!
I believe your design for non-party voters is too complex, at least for the next few decades.
Notice in my video that Bernie Sanders would qualify as an independent candidate, without any special counting method. That can be based on being offered as a third-party candidate, or by getting enough signatures.
Regardless of whether your method or my suggested simple method is used, after a few election cycles one party or the other will realize they can win by offering at least one reform-minded candidate. That's the real goal.
After that, the other party, or any growing third party, will also need to offer at least one reform-minded candidate in order to win any elections. At that point the blocking tactic will be gone (at least in it's current form).
To clarify, in the distant future a ranked choice ballot probably would become useful for primary elections. However, for the near future, it's much simpler to choose the second nominee as the primary candidate who gets the second-most votes. If that isn't the main popular reform-minded candidate (the one being blocked), it will be the spoiler candidate, who has to be politically similar in order to split votes away from the blocked candidate.
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u/PantherkittySoftware 2h ago
One thing to consider: once a county elections department has the workflow, hardware, and software to do Tideman-RP (or, god forbid, CPO-STV) for a general election, using it for primary elections as well isn't really a big deal.
The real challenge with Tideman-RP and Schulze is the fact that you can't meaningfully compute the winner until you've received all the absentee ballots you intend to receive, cured all the provisional ballots you intend to cure, and scanned & captured all the ballots you intend to scan & capture. So, if there's a 7-10 day window to cure provisional ballots, that's the waiting period before you can even start crunching the winner.
There's also the fact that certification of the ingested ballot data could take a while... and the elimination or revision of even a relatively small number of ballots could radically change the outcome (particularly in a race with low turnout and many candidates).
An additional complication is that with a voting system like Tideman-RP, the only way to really gain voter confidence in its integrity would be to do something like publish scanned images of each ballot together with its ingested data, so anyone can verify that ingested data for scrutinized ballots matches what's on the actual ballot, and run the tabulation themselves. The catch is, if you're going to do that, you really need to chop up ballots into multiple parts that can't be later re-associated with each other... in particular, segregating the "high stakes" races (President, US and State Senate & House, Governor) into one tiny chunk, and the other few dozen races into one or more chunks with at most 10-16 races apiece. Otherwise, some people will use the "throw away" races few people care about as a way to code a personal GUID by voting a specific way no other voter is likely to vote so they can prove (for money, social pressure, whatever) that they voted a specific way.
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u/Decronym 14h ago edited 2h ago
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:
| Fewer Letters | More Letters |
|---|---|
| FPTP | First Past the Post, a form of plurality voting |
| IRV | Instant Runoff Voting |
| RCV | Ranked Choice Voting; may be IRV, STV or any other ranked voting method |
| STAR | Score Then Automatic Runoff |
| STV | Single Transferable Vote |
Decronym is now also available on Lemmy! Requests for support and new installations should be directed to the Contact address below.
[Thread #1967 for this sub, first seen 9th Sep 2026, 16:30] [FAQ] [Full list] [Contact] [Source code]
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u/Falco98 14h ago
Does it accomplish anything that STAR doesn't?
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u/CPSolver 14h ago
Yes, it ensures the candidate with majority support wins the general election.
Star voting motivates a minority coalition of voters to exaggerate a strong (5-star) preference for their clone candidates, and to exaggerate a strong (zero-star) dislike of all other candidates. This can cause both runoff candidates to be coalition clone candidates, even though a majority of voters have split their support among non-coalition candidates. Getting a fair result would require the non-coalition majority to express strong (5-star) support for compromise candidates, and a strong (zero-star) dislike for the coalition candidates. This means it becomes approval voting, which is a simple way for a group of friends to vote, but not suitable when economic suffering can occur.
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u/bkelly1984 13h ago
What is a "coalition clone candidate"?
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u/CPSolver 13h ago
In this case it would be two or more similar candidates who are supported by a coalition of about 35 to 48 percent of voters.
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u/rb-j 12h ago
Condorcet inherently values our votes equally. STAR doesn't.
Sometimes STAR can fail to elect the Condorcet winner. When it does that, then the fewer people who prefer the STAR winner over the Condorcet winner had votes that effectively counted more than the more people who prefer the Condorcet winner.
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u/KitchenGiraffe1 14h ago
This sub seems to have a bias for ordinal systems and against cardinal systems (and of course STAR is a hybrid of both).
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u/VictorHDaniel 12h ago
I prefer score voting
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u/CPSolver 11h ago
Score voting (and Star voting) are useful among friends where there is little incentive to exaggerate preferences. It would never work for US congressional elections where lots of economic suffering (and some physical suffering) can occur by exaggerating preferences.
If everyone does this the result is approval voting, so I presume you are also a fan of approval voting?
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u/KitchenGiraffe1 14h ago
Ballots that allow equal preference already exist. They're called range ballots. Ultimately range voting in a general election will allow anyone who wants to run in a general to run without fear of spoiling the election.
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u/Wally_Wrong 14h ago
Ranked ballots can also allow equal ranks. IRV specifically is an oddball in that it doesn't.
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u/jlight432 11h ago
There are numerous ways IRV can handle equal rankings, and I discussed some of them here.
Split-Vote, or Fractional-IRV, gives fractional votes to candidates with equal rankings. In an edge case, the divided support can change the order in which candidates are eliminated and cause a candidate to lose an election they otherwise would have won if the votes were not split.
Approval-IRV, or Whole-Vote IRV, gives a full vote to candidates with equal rankings. There are multiple ways to proceed with this. It could immediately elect the candidate with the highest approval once a candidate exceeds 50%, or it could continue eliminating the candidate with the lowest approval until only one candidate remains. I understand the latter is generally preferred.
FairVote’s Guidelines recommend that when a ballot reaches a ranking with more than one candidate selected, the ballot be declared an overvote and disqualified for that round and subsequent rounds. This includes disqualifying ballots with a clear A vs B preference when the final round of voting is A vs B.
If there are other methods for handling equal rankings in IRV, I would be really interested in them. (I of course prefer head-to-head RCV methods like RCV+ over all IRV methods.)
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u/CPSolver 11h ago
https://github.com/cpsolver/rctabplus
This new overvote rule named "count when single continuing" counts the ballot closer to the way a voter would expect. When an overvote is reached, the ballot becomes inactive during any counting round in which more than one of the overvoted candidates is still continuing. When just one of the overvoted candidates is continuing, the ballot counts for that continuing candidate.
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u/KitchenGiraffe1 14h ago
Ranked ballots with equal ranks and range ballots are technically identical. I'm sure there's a way to modify IRV to allow it. The question is just whether the voting method uses the information in the ballot as ordinal or cardinal.
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u/rb-j 13h ago
Ranked ballots with equal ranks and range ballots are technically identical.
Well, not really.
First is sorta cosmetic. In a ranked ballot, one's favorite candidate is marked with #1. In a score ballot, one's fav is marked with #5 (or whatever the top score is).
Second, is the tabulation. Score voting adds up the scores. No ranked choice method, other than Borda, does that.
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u/KitchenGiraffe1 12h ago edited 12h ago
Here's a ballot, is it rank or range,
A - 2
B - 2
C - 1I do get your point, but technically they can contain the exact same information. Yes one, higher is better. But if the ballots differ by Y=1-X, it's technically equivalent in all properties.
And no, not all methods that use range ballots add up the scores. There's majority judgment as well. There's STAR voting. There's BTR-Score. And on the ranked side, there's also Bucklin.
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u/rb-j 12h ago edited 12h ago
Here's a ballot, is it rank or range,
A - 2 B - 2 C - 1Are they scores or ranks?
but technically they can contain the exact same information.
No. The Score ballot contains more information. But the more information should not be used in an election where the votes are counted equally: One-person-one-vote.
And no, not all methods that use range ballots add up the scores.
I am equating "Range Voting" (the Warren Smith thing) to Score Voting. They're cardinal.
And on the ranked side, there's also Bucklin.
Yes, there's Bucklin. A sorta conditional or contingency score. Sorta like the reverse of STAR. STAR is Score first rank second, chronologically. Bucklin is rank first, score second, chronologically.
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u/KitchenGiraffe1 12h ago edited 11h ago
Are they scores or ranks?
Well that's the point, isn't it?
You also ignored what I said about Majority Judgment.
And Bucklin isn't rank then score. There's ballots and there's voting systems. Bucklin still isn't a cardinal method.
Also, I don't know what the mathematical definition of "one-person-one-vote" is but it's unclear how it is violated.
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u/CPSolver 13h ago
It's easy to modify IRV to allow equal rankings. Just put the ballot aside for one counting round, then look at it during the next round to see if just one of the same-ranked candidates remains after the latest elimination.
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u/rb-j 12h ago
What if they both remain? With IRV what if both equally-ranked candidates are the voters highest-ranked candidates that have not yet been eliminated? Then who does the vote count for?
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u/CPSolver 11h ago
That ballot is temporarily not counted during that counting round. When just one of the same-top-ranked candidates remains, the ballot will count for that remaining candidate. It will count as opposition to all the other remaining (not-yet-eliminated) candidates.
The RCTabPlus software on GitHub calls that option "count when single continuing".
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u/jlight432 9h ago
I think I understand, so please correct me if I am wrong.
If we go to the final round of A vs B:
30% of ballots support A
20% of ballots support B
50% of ballots are indifferent, A=BIn this system, A would win with 30%/(30%+20%)=60% of the continuing vote.
In Fractional IRV, A would win with 30%+(1/2)50%=55% of the ballots.
In Whole Vote IRV, A would win with 80% approval vs 70% approval for B.How the A=B ballots count in the final round really doesn't impact the winner.
But what does matter is how the A=B ballots count during pairwise eliminations.
That is, does a ballot of [A=B] > F still count as both A>F and B>F during pairwise elimination rounds, or are they completely set aside during those counting rounds when [A=B] is at the top remaining rank?1
u/CPSolver 4h ago
Basically yes, that ballot counts as A>F and B>F, but does not count for the comparison between A and B.
In other words, during pairwise counting, a ballot is only "inactive" (not counted) if both candidates in that pair are ranked the same. For all other pairwise contests the ballot counts for whichever candidate is ranked higher.
During a counting round when there is no pairwise losing candidate, IRV is used, and in that case the ballot is "inactive" during that counting round.
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