[EM] PR for USA or UK

[Toby Pereira]

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.quinn at gmail.com>
To: EM <election-methods at 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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