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IRV failing to capture voter preferences is not a "corner case". It is absolutely unclear that IRV is better at all than FPTP. See a set of voting simulations w

by jquery 7y ago

IRV failing to capture voter preferences is not a "corner case". It is absolutely unclear that IRV is better at all than FPTP. See a set of voting simulations with candidates and distributions here for different voting methods: http://zesty.ca/voting/sim/ http://zesty.ca/voting/sim/ Alarmingly, IRV is the worst voting system of all just by eyeballing these simulations. The charts it produces are bizarre, and it tends to select for extremists and/or candidates that do not capture the voter's preferences! It's not just of theoretical interest either, IRV famously spoiled the 2009 Burlington mayoral election, resulting in its repeal: https://en.wikipedia.org/wiki/2009_Burlington_mayoral_election https://en.wikipedia.org/wiki/2009_Burlington_mayoral_electi... The only good takeaway from IRV picking up steam is that maybe it puts us on the path towards something like approval voting, which is much harder to game, and is much easier for voters to understand (I doubt more than 1 out of 10 people could explain how IRV works).

JAlexoid 7y ago
There should be a rule - no majority = no win. Let alone - anything is better, than a simple plurality based system.
- einpoklum 7y ago
  Very often when there are more than two candidates, none of them have a majority of supporters. In fact, sometimes that's true even with two or even one candidate...
- birdyrooster 7y ago
  What do you do when votes lead to a plurality?
- SlowRobotAhead 7y ago
  What election are you thinking of where majority of votes didn’t win? Because if you say 2016 / electoral college, I’ll have to remind you that the winner had a fairly vast majority. If you are thinking Canada or some ranked system, iirc they still elect by majority. “No majority no win” is a great recipe for tyranny of the majority and why we have representative democracies, isn’t it?
  - munk-a 7y ago
    Canada uses FPTP voting and it has highly skewed the last few elections, sadly there was an expectation that the last federal election would result in election reform but that never materialized.
  - eyelidlessness 7y ago
    > What election are you thinking of where majority of votes didn’t win? https://en.wikipedia.org/wiki/United_States_presidential_elections_in_which_the_winner_lost_the_popular_vote https://en.wikipedia.org/wiki/United_States_presidential_ele... > Because if you say 2016 / electoral college, I’ll have to remind you that the winner had a fairly vast majority If you mean the winner who lost, sure?
    - dragonwriter 7y ago
      The winner of the 2016 election received the majority of the votes cast in the electoral college by Presidential electors Those electors voting for the winner were themselves, however, elected by only a minority of those voting for Presidential electors in elections which misleading had the name of Presidential candidates but not electors on the ballots.
      - eyelidlessness 7y ago
        This is pointlessly pedantic. The person clearly meant they preferred elections be won by a majority of the popular vote.
        SlowRobotAhead 7y ago
        In the USA we don't use popular vote. We use state votes. The winner won with a vast majority of those state votes. You can be upset at the outcome, but you can not argue the facts of the system.
        eyelidlessness 7y ago
jefftk 7y ago
Voter Satisfaction Efficiency (http://electionscience.github.io/vse-sim/VSE/ http://electionscience.github.io/vse-sim/VSE/) is another way of looking at different options, and IRV compares very poorly by it
- joveian 7y ago
  That is very interesting and I hadn't seen it before. IRV still does better than plurality by quite a bit, although it doesn't do well compared to the rest. As the chart shows, one of the biggest outliers is 100% honest voting with plurality. I hadn't heard of 3-2-1 voting before but that is interesting. Maybe it would be one of the best. I generally prefer ranking to scoring (I'm not sure how much better someone prefers a candidate should really be part of the process) but the simpler tallying and presentation of results is nice. I also like that in the "scenereo type" breakdown the easy case gets the best results, condorcet cycles get the worst results, and the rest are in the middle (all with little effect of strategy). It seems like the right distribution to me, but none of the other methods measured get that distribution. IMO a ranked preference is usually much easier to determine how to vote (although it can still be an issue when some candidates are much closer than others), although I guess the limited effect of strategic voting should hopefully mean that it usualy doesn't make much difference exactly how you vote. OTOH, at least the names of the options should be changed; it is the rare race where I could describe any of the candidates as anything other than "bad". https://electowiki.org/wiki/3-2-1_voting https://electowiki.org/wiki/3-2-1_voting IMO, proportional representation would be a much better change of voting system rather than just changing the method. Voting for one person is almost always going to leave lots of people unrepresented.
- thaumasiotes 7y ago
  I hate the way they've defined their metric: > VSE is expressed as a percentage. A voting method which could read voters minds and always pick the candidate that would lead to the highest average happiness would have a VSE of 100%. A method which picked a candidate completely at random would have a VSE of 0%. In theory, VSEs down to negative 100% would be possible if a voting method did worse than a random pick If VSE is going to be a percentage, it should be a percentage of the maximum happiness -- that is, the total happiness if everyone got their first choice, not the total happiness that is the highest any candidate can actually achieve. I say this mostly because it's much easier to calculate. But more fundamentally, there is no reason to expect the worst-case candidate to be equally as bad as the best-case candidate is good. It's a huge mistake to rank systems on a scale from +100% to -100% where the units on the positive and negative "halves" of the scale are different! And it's also a mistake to define 0% as whatever sortition achieves. It's trivial to construct a pathological system in which 0% VSE is equal to 100% VSE. (Everyone is equally un/happy with all candidates.) This should be impossible.
r1nkgrl 7y ago
IRV picking up steam might also have negative effects towards people's general opinion of alternative voting systems once they see all the strange outcomes it can have. But I think that the positives attention around it brings outweigh the negatives. The first (recent) overhaul to a voting system is more difficult than subsequent changes.
munk-a 7y ago
As someone who voted in the 2009 election I disagree that IRV actually spoiled the election, people - when voting in an IRV system, need to comprehend that they don't need to rank all candidates and doing an exhaustive ranking is a tactical decision to vote against an ultimate candidate. That "spoilage" ended up being less about IRV and more about the fact that Bob Kiss was someone a lot of people ranked without good knowledge of him was more at issue, along with his personal character. Don't forget that he wasn't some 5th place follower who managed to pick up protest votes, he was the 2nd place candidate in the primary round. I just wanted to add, the fact that IRV was repealed over this removal from office was a travesty and the result of shady politics - please understand this is a terrible case study.
amalcon 7y ago
This particular example is a bit of a corner case, as it has no Condorcet winner. This is rare: https://en.m.wikipedia.org/wiki/Condorcet_paradox#Likelihood_of_the_paradox https://en.m.wikipedia.org/wiki/Condorcet_paradox#Likelihood... IRV still has serious failure modes in its typical deployment, but this is not a great example.
- jakelazaroff 7y ago
  The Wikipedia article for this particular example says Andy Montroll, the Democratic candidate, was the Condorcet winner.
  - amalcon 7y ago
    Gah, too many examples. I was referring to the synthetic example further upthread.

by jquery 7y ago

JAlexoid 7y ago

There should be a rule - no majority = no win. Let alone - anything is better, than a simple plurality based system.

einpoklum 7y ago
Very often when there are more than two candidates, none of them have a majority of supporters. In fact, sometimes that's true even with two or even one candidate...
birdyrooster 7y ago
What do you do when votes lead to a plurality?
SlowRobotAhead 7y ago
What election are you thinking of where majority of votes didn’t win? Because if you say 2016 / electoral college, I’ll have to remind you that the winner had a fairly vast majority. If you are thinking Canada or some ranked system, iirc they still elect by majority. “No majority no win” is a great recipe for tyranny of the majority and why we have representative democracies, isn’t it?
- munk-a 7y ago
  Canada uses FPTP voting and it has highly skewed the last few elections, sadly there was an expectation that the last federal election would result in election reform but that never materialized.
- eyelidlessness 7y ago
  > What election are you thinking of where majority of votes didn’t win? https://en.wikipedia.org/wiki/United_States_presidential_elections_in_which_the_winner_lost_the_popular_vote https://en.wikipedia.org/wiki/United_States_presidential_ele... > Because if you say 2016 / electoral college, I’ll have to remind you that the winner had a fairly vast majority If you mean the winner who lost, sure?
  - dragonwriter 7y ago
    The winner of the 2016 election received the majority of the votes cast in the electoral college by Presidential electors Those electors voting for the winner were themselves, however, elected by only a minority of those voting for Presidential electors in elections which misleading had the name of Presidential candidates but not electors on the ballots.
    - eyelidlessness 7y ago
      This is pointlessly pedantic. The person clearly meant they preferred elections be won by a majority of the popular vote.
      - SlowRobotAhead 7y ago
        In the USA we don't use popular vote. We use state votes. The winner won with a vast majority of those state votes. You can be upset at the outcome, but you can not argue the facts of the system.
        eyelidlessness 7y ago

jefftk 7y ago

Voter Satisfaction Efficiency (http://electionscience.github.io/vse-sim/VSE/ http://electionscience.github.io/vse-sim/VSE/) is another way of looking at different options, and IRV compares very poorly by it

joveian 7y ago
That is very interesting and I hadn't seen it before. IRV still does better than plurality by quite a bit, although it doesn't do well compared to the rest. As the chart shows, one of the biggest outliers is 100% honest voting with plurality. I hadn't heard of 3-2-1 voting before but that is interesting. Maybe it would be one of the best. I generally prefer ranking to scoring (I'm not sure how much better someone prefers a candidate should really be part of the process) but the simpler tallying and presentation of results is nice. I also like that in the "scenereo type" breakdown the easy case gets the best results, condorcet cycles get the worst results, and the rest are in the middle (all with little effect of strategy). It seems like the right distribution to me, but none of the other methods measured get that distribution. IMO a ranked preference is usually much easier to determine how to vote (although it can still be an issue when some candidates are much closer than others), although I guess the limited effect of strategic voting should hopefully mean that it usualy doesn't make much difference exactly how you vote. OTOH, at least the names of the options should be changed; it is the rare race where I could describe any of the candidates as anything other than "bad". https://electowiki.org/wiki/3-2-1_voting https://electowiki.org/wiki/3-2-1_voting IMO, proportional representation would be a much better change of voting system rather than just changing the method. Voting for one person is almost always going to leave lots of people unrepresented.
thaumasiotes 7y ago
I hate the way they've defined their metric: > VSE is expressed as a percentage. A voting method which could read voters minds and always pick the candidate that would lead to the highest average happiness would have a VSE of 100%. A method which picked a candidate completely at random would have a VSE of 0%. In theory, VSEs down to negative 100% would be possible if a voting method did worse than a random pick If VSE is going to be a percentage, it should be a percentage of the maximum happiness -- that is, the total happiness if everyone got their first choice, not the total happiness that is the highest any candidate can actually achieve. I say this mostly because it's much easier to calculate. But more fundamentally, there is no reason to expect the worst-case candidate to be equally as bad as the best-case candidate is good. It's a huge mistake to rank systems on a scale from +100% to -100% where the units on the positive and negative "halves" of the scale are different! And it's also a mistake to define 0% as whatever sortition achieves. It's trivial to construct a pathological system in which 0% VSE is equal to 100% VSE. (Everyone is equally un/happy with all candidates.) This should be impossible.

r1nkgrl 7y ago

IRV picking up steam might also have negative effects towards people's general opinion of alternative voting systems once they see all the strange outcomes it can have. But I think that the positives attention around it brings outweigh the negatives. The first (recent) overhaul to a voting system is more difficult than subsequent changes.

munk-a 7y ago

As someone who voted in the 2009 election I disagree that IRV actually spoiled the election, people - when voting in an IRV system, need to comprehend that they don't need to rank all candidates and doing an exhaustive ranking is a tactical decision to vote against an ultimate candidate. That "spoilage" ended up being less about IRV and more about the fact that Bob Kiss was someone a lot of people ranked without good knowledge of him was more at issue, along with his personal character. Don't forget that he wasn't some 5th place follower who managed to pick up protest votes, he was the 2nd place candidate in the primary round. I just wanted to add, the fact that IRV was repealed over this removal from office was a travesty and the result of shady politics - please understand this is a terrible case study.

amalcon 7y ago

This particular example is a bit of a corner case, as it has no Condorcet winner. This is rare: https://en.m.wikipedia.org/wiki/Condorcet_paradox#Likelihood_of_the_paradox https://en.m.wikipedia.org/wiki/Condorcet_paradox#Likelihood... IRV still has serious failure modes in its typical deployment, but this is not a great example.

jakelazaroff 7y ago
The Wikipedia article for this particular example says Andy Montroll, the Democratic candidate, was the Condorcet winner.
- amalcon 7y ago
  Gah, too many examples. I was referring to the synthetic example further upthread.