Lottery PR methods compared
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I know some people are against any lottery methods in principle, but we can still have academic discussions of their various properties and pros/cons. I discussed some of this here as well.
@toby-pereira said in The search for the "holy grail" and non-deterministic methods:
I actually think there are advantages to having non-deterministic PR methods. The main advantage is that you can get a better level of PR and you don't sacrifice proportionality by having small regions. If an ideology or party has 5% of the support across the country, then it should get about 5% of the representation. If you have regions with e.g. 5 representatives and it's done deterministically, it might get none. It also simplifies the process. PR methods can get very complex with all the calculating of quotas etc., whereas just picking ballots at random cleans this up. It also means that for politicians there are no "safe seats". There is always a chance of being ejected, so they have to appeal to as many people as possible, not just their usual fan base.
Single non-transferable vote is a simple non-deterministic method, but in practice it would give horrible results and strategising effectively would be required to make it proportional. Anyway, here are some of the lottery methods:
Random Ballot - This is single-winner in its normal form, but used in multiple regions across the country, it would give a form of nationwide PR. The pros are that its very simple to vote and to count, and the best strategy is to vote for your favourite. Cons are that it's very "knife-edge" with only one ballot per region affecting the result. Even very strong candidates are likely not to get elected.
Ranked multi-winner random ballot - This is where each region has multiple winners (say 6) and voters rank their top 6 candidates. Ballots are picked at random and the highest ranked non-elected candidate on each ballot is elected until all seats are filled. Pros are that it's still simple to vote and count, but specifically with several candidates elected in each region it's less knife-edge and each voter has several MPs that are "theirs". Particularly popular candidates are unlikely to miss out. A con is that as with normal random ballot, the number of ballots that have any say in the result is still equal to the number of elected candidates, so very low. It is also no longer completely strategy free.
COWPEA Lottery - See wiki description. Pros are that it's still simple to vote and count. Voting is approval style. Because multiple candidates can be approved on a single ballot, picking one ballot does not necessarily determine the next candidate to be elected so more ballots are picked. So a pro of this method is that more ballots are used to determine the election result than with random ballot making it more inclusive of the electorate. It's likely to be less knife-edge and more consistent in the results it produces in multiple iterations. It's probably a more "accurate" form of PR than random ballot. A con is that a voter has to decide how many candidates to approve and it's likely to be a slightly more complex process for them with more strategy involved as well.
COWPEA Lottery with layers of approval - Voters score or grade candidates. The actual values are irrelevant, but when a ballot is picked at random only the top layer of (relevant) candidates is looked at. A pro is that it gives voters more distinguishing power between candidates. The cons are that it becomes more complex and to vote optimally a voter would have to grade basically all of the candidates, which could be quite a lot of them.
COWPEA Lottery with KP Transformation - A score voting version. The KP transformation can give nice results in theoretical cases with honest voting, but I don't think it's probably useful in practice. Mentioned for completeness.
Weighing up simplicity and giving reasonable results, I think the two main candidates are Ranked multi-winner random ballot and COWPEA Lottery (the standard approval version). At the moment I'm leaning towards COWPEA Lottery as more ballots get used, and the results are likely to be theoretically better.
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@toby-pereira definetly agree there are some good point about random elements in a voting method. Not only because - as you say - it simplifies and achieves PR but also the psychological effect on elected candidates ("luck was part of my succes") may lead to more empathy, humbleness in their policies, and dealing with colleagues and their next campaign.
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@toby-pereira seems a method is missing that selects randomly ballots and only compares the scores of a random pair (counting only the highest scoring as a winner of that pair).
Also including a concept like : repeat until chance of statistical unrepresentativeness becomes f.i less then 0,001% -
@multi_system_fan Yeah, it wasn't necessarily intended as an exhaustive list. Would you be able to clarify those methods in a bit more detail?
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@toby-pereira said in Lottery PR methods compared:
COWPEA Lottery with layers of approval - Voters score or grade candidates. The actual values are irrelevant, but when a ballot is picked at random only the top layer of (relevant) candidates is looked at. A pro is that it gives voters more distinguishing power between candidates. The cons are that it becomes more complex and to vote optimally a voter would have to grade basically all of the candidates, which could be quite a lot of them.
This one could be used nicely with the 0 to 5 "star" ballot. So to clarify the process to elect a candidate - pick a ballot at random and eliminate all but the top or joint top rated candidates on that ballot. Pick another ballot and retain only the candidate(s) that are the highest rated among those still in contention. Continue until one candidate remains. Elect that candidate.
