I agree that PRV would give better results, with sophisticated voters, than most forms of PR. However, it does fail my criterion 4 (simple ballots) and do worse than SODA-PR on criteria 5(smooth transition) and even arguably 1(true proportionality - because separate districts spoil the proportionality). If you don't think these criteria are reasonable, you should give that argument.
I started out with a list of criteria because I think that's the right place to start when you're looking for a practical system. JQ 2011/7/23 Toby Pereira <tdp2...@yahoo.co.uk> > My preferred system of proportional representation is proportional range > voting. Each voter gives the candidates a score and the result are > calculated from this. I have my own system of PRV - > http://www.tobypereira.co.uk/voting.html - which I prefer to Warren's > Reweighted Range Voting for various reasons. Mine can also be converted to a > sequential method if computing power deems it necessary. > > So we would have geographical constituencies with several seats available > in each, and candidates would be elected accordingly. No need to vote for > parties. You would purely be voting for the candidates in your geographical > constituency. > > Why range voting? I make an argument here - > http://www.tobypereira.co.uk/voting2.html - but I'll summarise. First of > all, I think that the argument for range ballots over ranked ballots is > (even) greater for PR than it is for single-winner elections. STV with > ranked ballots assumes that you want to get your first choice elected over > any number of your next preferences, and so only when that is settled, will > your vote be used further down your preference list (if it still can be). > 1st choice > 2nd + 3rd + 4th. But it's not as if it can make any other > assumption either because that would be a guess too. Also there's Warren's > example here - http://rangevoting.org/PRcond.html. By submitting a range > ballot, you are indicating how much you like each candidate. Strategy aside, > I would argue that a proportional form of range voting is probably the > purest form of PR there is. > > So what about strategy? Would strategy ruin the "purity" of proportional > range voting? I don't think it would too much. Unless the voters of some > candidates are better at voting strategically than the voters of others, > then I don't see it as too much of a problem. And no system would be > entirely free from strategy. Specifically under PRV, people might vote down > some of their preferences if they think it's likely they'll be elected > anyway. It's a bit of a risk though, so I'm not sure it would happen too > much. If we can trust Warren's Bayesian Regret figures for single-winner > cases and range voting generally comes out on top there, I don't think it > would be too much of a stretch to imagine that it might also come out on top > for multiple winners. > > And I would argue that more "strategy-resistent" systems generally work by > basically doing the strategy for you, so already give "dishonest" results. > So it's not that they give better results. On my website I give an example > where party A has 68% of the support and party B 32%. There are two seats > and so each party fields two candidates. Assuming everyone would vote > approval style, under my system, they would win one each. Party A would need > over 75% of the votes to win the second seat. I would argue that this is a > fair result (75% being bang in the middle between 50% and 100% - the amount > to exactly earn one and two seats). Of course party A voters could > coordinate themselves and split into two factions of 34% to take both seats, > but this would be very hard for them to achieve. STV (Droop quota > anyway) would transfer the votes above the quota accordingly so that party A > would win both seats, and give what I would regard as the less fair result. > > By the way, I tend to think quotas, whether Droop or Hare, all end up being > fairly arbitrary. Droop is supposed to be the "best" because it's supposedly > set as low as possible, but in reality it isn't. It's not as if all > elected candidates ever end up exactly on the quota so unless you have a > moveable quota then it always ends up being too high and more votes could be > transferred away. > > I'm probably not acquainted enough with SODA or SODA-PR to give a full > argument against it, but generally I think that voters would regard the idea > of giving their votes to candidates in a delegable manner as just too weird. > I'm not sure people would really get the point of it and would just want to > have their own ranked list of candidates instead (and as we know, ranking > isn't as good as range!) I'm not sure it would give better result than PRV > anyway, or even Proportional Approval Voting (again, my version of it), and > I'd have PAV as my second choice if PRV was deemed too complicated. I don't > think it is too complicated though. It's not any more complicated for the > voter than STV, and scores can be out of a low number if need be. 6 would be > fine. > > ------------------------------ > *From:* Jameson Quinn <jameson.qu...@gmail.com> > *To:* EM <election-methods@lists.electorama.com> > *Sent:* Sat, 23 July, 2011 15:45:04 > *Subject:* [EM] PR for USA or UK > > We had a discussion about the best practical single-winner proposal, which, > while it certainly wasn't as conclusive as I'd hoped, seemed productive to > me. I think we should have a similar discussion about PR. > > Obviously, the situations in the UK and in the USA are very different in > this regard. The UK is, as far as I know, the origin of the PR movement (in > the 1860s and 1870s, liberals gained seats disproportionately as the > franchise was extended, and Conservatives looked for a "fairer" system to > recoup their losses). And it's part of Europe, where people have experience > with PR. But both the UK and the US currently elect their principal > representative bodies by district-based FPTP/plurality. > > And so I'd like to suggest that we should be looking for a PR system which > satisfies the following criteria: > > 1. Truly proportional (of course). I would be willing to support a > not-truly-proportional system, but I'm not everyone. Egregious compromises > on this issue will simply reduce the activist base, to no benefit. > 2. Includes a geographical aspect. People are attached to the "local > representation" feature of FPTP, whether that's rational or not. > 3. No "closed list". A party should not be able to completely shield any > member from the voters. In general, voter power is preferable to party > power, insofar as it's compatible with the next criterion. > 4. Simple ballots. A reasonably-thorough voter should not have to mark more > than, say, 5 candidates or options, and an average ballot should not list > more than 20 candidates or options. Those are extreme limits; simpler is > better, all the way down to around 7 options (of which only around half will > be salient and/or viable). > 5. Ideally, the smoothest transition possible. If existing single-winner > districts can be used unchanged, all the better. > 6. Insofar as it's compatible with the criteria above, greater freedom in > voting is better. For instance, if ballots are printed with only in-district > candidates, a system which allows out-of-district write-ins is better than > one which doesn't, all other things being equal. > > My proposal for SODA-PR satisfies and surpasses all 5 criteria. Other > systems which do reasonably well: > -I've seen a proposal for single-member districts and open party lists. > This is similar to my SODA-PR system, except that it requires that all > candidates in a party approve the same party set. As such, it is strictly > worse on criterion 3, without being notably better on any of the other > criteria. It is more conventional, though. > -Multimember districts, with some system inside each district. > -Mixed member systems. > > Still, I would argue that SODA-PR sets a high water mark on all the > criteria I mentioned, and is therefore the system to beat. I'm somewhat > surprised that it hasn't gotten more comments. I'd especially like it if > people could come up with clever mechanisms to (virtually) ensure > that discarding whole ballots gives the same results as fractional ballot > reweighting, using some probabilistic wording or process. (For instance: > "When choosing seat N+1, select the previous N seats with random discarding > until you get the same answer three times"... needs work I think. Or a proof > that the fractional process is always the highest-probability result of the > random-discard process - which I'm sure is very close to true, but not sure > is true - so that you could write a statute to just say "highest-probability > result".) > > JQ >
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