8 ms·

As far as I can tell RCV is equivalent to what we've been using in Australia since federation to elect lower house candidates (we call it prefential voting and

As far as I can tell RCV is equivalent to what we've been using in Australia since federation to elect lower house candidates (we call it prefential voting and use it at all levels of government). I'm curious in what case "increasing your support for your genuine favorite can actually hurt their odds of winning"? I skimmed the link to the article you referenced and it appears that there were two republican candidates which is the main reason neither won - I don't believe I've ever seen a case here where one party had two candidates on the same ballot paper and I suspect it's probably illegal. I've also never seen a ballot paper with more than about 15 choices (and it's very rarely more than 10), so vote splitting is rarely a problem (it can be for minor parties with similar policies/leanings etc.). On that basis I'm pretty sure there's never been a case in this country where anyone has lost an election due to gaining higher primary levels of support - indeed it's pretty rare that the winning candidate doesn't have at least 35% of the primary vote (though exactly that happened in our recent federal election, as a total across all seats), and exceedingly rare for it to be less than 30%. There are certainly plenty of cases where the winner isn't the one with the highest primary vote, but it's typically only a few percentage points lower, and mostly affects the more progressive candidate because for many seats there are two such candidates with solid levels of support but only one mainstream conservative candidate.

tim-- 4y ago
I don't believe that there is anything stopping two candidates from one party. I believe I have even seen it before, but I can't find a reference.
- wizofaus 4y ago
  Doesn't seem compatible with the idea of "two-party preferred" voting which is what's actually used in practice here, though I'm not 100% clear as to whether that's explicitly different to preferential voting/RCV.
  - aldonius 4y ago
    Two party preferred is more a statistical count done on the assumption that {Labor, Coalition} = {Government, Opposition}. Of course it'll be decreasingly relevant now if the teals can stick.
godelski 4y ago
> "increasing your support for your genuine favorite can actually hurt their odds of winning" This is referring to the monotonicity criterion[0]. The page has both toy examples and real world ones. It includes some hints about possible violations in Australia, but your voting system isn't very transparent so it is difficult to audit these situations. As for vote splitting, I think it would be better to look at Favorite Betrayer[1][2]. Sometimes also called the strong spoiler effect. This is actually a big problem. It is why candidates like Bernie Sanders pledge to not run as independent after losing the primary. If you don't violate this condition such pledges are entirely unnecessary. [0] https://electowiki.org/wiki/Monotonicity https://electowiki.org/wiki/Monotonicity [1] https://electowiki.org/wiki/Favorite_betrayal_criterion https://electowiki.org/wiki/Favorite_betrayal_criterion [2] https://electionscience.org/library/the-spoiler-effect/ https://electionscience.org/library/the-spoiler-effect/ [0] https://electowiki.org/wiki/Monotonicity https://electowiki.org/wiki/Monotonicity
- wizofaus 4y ago
  Sure, thanks, I can see how it can happen now, and actually it revealed my understanding of preferential voting wasn't entirely correct. As for "favorite betrayal criterion" - I actually think it's a feature of preferential voting that I actually take advantage of, whereby I vote [1] for a minor candidate who has policies I agree with but I accept is not in a realistic position to govern effectively (due to lack of experience/resources etc.), but [2] for the party that I'm happy to actually win, providing they're aware they're relying on 2nd preference votes from another party that they can't just ignore.
  - godelski 4y ago
    So it sounds like you're trying to strategically vote to push a party you want in another direction. I totally understand this, but under score or star (where we have more resolution that approval) it is very easy to just extract this information out of an honest ballot. You can measure the distance between the voters and other candidates as well as the distance between your mean voter and other candidates. You have full information about which direction you should alter your course to better serve your population. Approval gives you this information too, it is just not as fine grained. My main (long) post in the thread argues that the advantage of cardinal systems is its ability to effectively embed voter preference better. What I'm talking about here is just extracting that information and that candidates can utilize that information without ever relying on voters to vote strategically.

tim-- 4y ago

I don't believe that there is anything stopping two candidates from one party. I believe I have even seen it before, but I can't find a reference.

wizofaus 4y ago
Doesn't seem compatible with the idea of "two-party preferred" voting which is what's actually used in practice here, though I'm not 100% clear as to whether that's explicitly different to preferential voting/RCV.
- aldonius 4y ago
  Two party preferred is more a statistical count done on the assumption that {Labor, Coalition} = {Government, Opposition}. Of course it'll be decreasingly relevant now if the teals can stick.

godelski 4y ago

> "increasing your support for your genuine favorite can actually hurt their odds of winning" This is referring to the monotonicity criterion[0]. The page has both toy examples and real world ones. It includes some hints about possible violations in Australia, but your voting system isn't very transparent so it is difficult to audit these situations. As for vote splitting, I think it would be better to look at Favorite Betrayer[1][2]. Sometimes also called the strong spoiler effect. This is actually a big problem. It is why candidates like Bernie Sanders pledge to not run as independent after losing the primary. If you don't violate this condition such pledges are entirely unnecessary. [0] https://electowiki.org/wiki/Monotonicity https://electowiki.org/wiki/Monotonicity [1] https://electowiki.org/wiki/Favorite_betrayal_criterion https://electowiki.org/wiki/Favorite_betrayal_criterion [2] https://electionscience.org/library/the-spoiler-effect/ https://electionscience.org/library/the-spoiler-effect/ [0] https://electowiki.org/wiki/Monotonicity https://electowiki.org/wiki/Monotonicity

wizofaus 4y ago
Sure, thanks, I can see how it can happen now, and actually it revealed my understanding of preferential voting wasn't entirely correct. As for "favorite betrayal criterion" - I actually think it's a feature of preferential voting that I actually take advantage of, whereby I vote [1] for a minor candidate who has policies I agree with but I accept is not in a realistic position to govern effectively (due to lack of experience/resources etc.), but [2] for the party that I'm happy to actually win, providing they're aware they're relying on 2nd preference votes from another party that they can't just ignore.
- godelski 4y ago
  So it sounds like you're trying to strategically vote to push a party you want in another direction. I totally understand this, but under score or star (where we have more resolution that approval) it is very easy to just extract this information out of an honest ballot. You can measure the distance between the voters and other candidates as well as the distance between your mean voter and other candidates. You have full information about which direction you should alter your course to better serve your population. Approval gives you this information too, it is just not as fine grained. My main (long) post in the thread argues that the advantage of cardinal systems is its ability to effectively embed voter preference better. What I'm talking about here is just extracting that information and that candidates can utilize that information without ever relying on voters to vote strategically.