If there are more than 3 candidates with any votes, eliminate the least popular, and redistribute those votes according to the voters’ next favourite choice.
What happens if there’s a tie? E.g. if there are 4 candidates with 30, 20, 10, 10 votes each.
I guess it’s unlikely to be determinant in practice but might be worth stating just in case.
My first guess is that if this did happen, we’d keep the votes open slightly longer until there wasn’t a tie—this is another benefit of having a secret deadline. I’ll check with @Will Howard🔹 when he’s online to see if there is already a solution to this. Thanks for pointing it out!
(Discussed separately) I think it would be best to split the pot 4 ways if this happens, because there is some chance of introducing a bias by deciding when to end based on a property of the votes. Or if there is some reason we can’t do this that I’m not aware of (e.g. legal constraints), then breaking the tie with a coin flip.
(@Lorenzo Buonanno🔸 You can consider this the official answer unless I hear otherwise).
There can be ties at any point during the iterative elimination process, not just during the final round (if anything they are more likely in earlier rounds).
From the link above:
For small IRV elections, there can be frequent last-place ties that prevent clear bottom elimination, so it’s critically important to have a clear tie-breaking mechanism in jurisdictions with few voters.
Ah, I hadn’t thought of that, and I can see how this makes the results indeterminate (because reallocating the votes from one joint-last candidate could bump the other joint-last candidate up from the bottom).
I’ll have a think about how to handle this and get back to you, my initial thought is still to break ties randomly (with a stable-but-random ranking of the precedence of each candidate in a tie).
Not that I expect the election administrators to be unsporting, but there should be an explicit norm that they do not vote after the evening of December 2 as they could not only snipe but maybe even cast a de facto tiebreaking vote on December 3 with inside knowledge. (I know of at least EA-adjacent place where using inside information to one’s advantage is seen as fine, hence the desire to be clear here.)
What happens if there’s a tie? E.g. if there are 4 candidates with 30, 20, 10, 10 votes each.
I guess it’s unlikely to be determinant in practice but might be worth stating just in case.
ETA: https://​​electowiki.org/​​wiki/​​Instant-runoff_voting#Handling_ties_in_IRV_elections
My first guess is that if this did happen, we’d keep the votes open slightly longer until there wasn’t a tie—this is another benefit of having a secret deadline. I’ll check with @Will Howard🔹 when he’s online to see if there is already a solution to this. Thanks for pointing it out!
(Discussed separately) I think it would be best to split the pot 4 ways if this happens, because there is some chance of introducing a bias by deciding when to end based on a property of the votes. Or if there is some reason we can’t do this that I’m not aware of (e.g. legal constraints), then breaking the tie with a coin flip.
(@Lorenzo Buonanno🔸 You can consider this the official answer unless I hear otherwise).
There can be ties at any point during the iterative elimination process, not just during the final round (if anything they are more likely in earlier rounds).
From the link above:
Ah, I hadn’t thought of that, and I can see how this makes the results indeterminate (because reallocating the votes from one joint-last candidate could bump the other joint-last candidate up from the bottom).
I’ll have a think about how to handle this and get back to you, my initial thought is still to break ties randomly (with a stable-but-random ranking of the precedence of each candidate in a tie).
Not that I expect the election administrators to be unsporting, but there should be an explicit norm that they do not vote after the evening of December 2 as they could not only snipe but maybe even cast a de facto tiebreaking vote on December 3 with inside knowledge. (I know of at least EA-adjacent place where using inside information to one’s advantage is seen as fine, hence the desire to be clear here.)
Fair enough!
I publicly declare that the people with knowledge of the deadline will not vote after the evening of December 2.
I’ll also make sure that we pre-commit internally to a deadline, so that we can’t game the results by choosing the cut off.