[EM] STV+AV

[Jameson Quinn]

2012/2/4 Bryan Mills <bmills at alumni.cmu.edu>

> > From: Bryan Mills <bmills at alumni.cmu.edu>
>> > To: David L Wetzell <wetzelld at gmail.com>
>> > > If there are 3-5 seats STV then the number of candidates won't
>> > proliferate
>> > > too much and there'd be 5-7 places to vote.  This would keep things
>> > > reasonable.
>> >
>> > To get reasonable proportionality with only 3-5 seats per district
>> > you'd probably need to go to an MMP system, with all its added
>> > complexity.  Otherwise Droop proportionality doesn't buy you much over
>> > FPTP; with 5 seats the Droop quota measures to a precision of ~17%,
>> > and the remaining 17% in each district is still susceptible to
>> > gerrymandering.
>> >
>>
>> Not much?
>> The goal here is not perfectionism wrt proportionality.
>> The goal is to increase proportionality and to increase the number of
>> competitive seats
>> and to reduce the cut-throat competitive nature of US political rivalry
>> between its two biggest parties
>> so they can't dominate the other and have more incentives thereby to work
>> together on the many issues that need work.
>>
>
> I'm doubtful that 3-5 candidate districts actually would "increase the
> number of competitive seats".  Each major party ends up with 1-2 safe
> seats, and at that level of granularity gerrymandering and geographical
> polarization are still significant enough to render the last seat
> non-competitive in most districts.  (It would increase proportionality
> somewhat - by transforming some of the safe-by-gerrymandering seats into
> safe-by-Droop-proportionality seats - but you seem to be arguing that
> proportionality isn't as important as competition.)
>
> Suppose we have two parties with a 50/50 split and 5 seats per district,
> with one party more popular in urban areas and one more popular in rural
> areas.  And suppose that the district lines are drawn such that 4/5 of
> districts are slightly more rural than average and 1/5 of districts are
> more urban than average, so that the 5th seat in each district becomes
> relatively safe as well.  (We can do this fairly easily using geographical
> boundaries by centering 1/5 of the districts around cities.)
>
> Scale that up to 400 legislators (80 districts).  What do we end up with?
> 320 "natural" safe seats guaranteed by Droop proportionality (160 for each
> party)
> 80 gerrymandered-safe seats for the rural party
> 20 gerrymandered-safe seats for the urban party
>

First, your numbers add up to 420. I think you meant 64/16 for the safe
seats, which is only a 56/44 advantage, not 60/40.

Note that the "safe" seats would still swing if there were a swing in
national mood of around something less than 8%, not something less than 25%
as in single-member districts. And the more highly-gerrymandered the map
is, the tighter that margin, and so the greater the chances of it
backfiring against the gerrymandering party. Gerrymandering is a fine art,
but 8% doesn't leave a whole lot of room to play with. Considering safety
margins and misfires, I doubt that the gerrymandering party could get
anything close to the 6% representation advantage your (corrected) numbers
suggest. So, while 2-3% unfairness is still a problem, I think it's a big
step up from where we are.


>
> Now, despite a 50/50 natural split, the rural party has a 60%
> supermajority.  And, of course, if you draw the district lines differently
> you can do the same thing for the urban party.
>
> So there's still relatively little hope that a system with such small
> districts would produce a party-proportional legislature.  As you point out
> elsewhere, it might still be possible to get an ideologically-proportional
> legislature if you can get the parties themselves to shift ideologies.
>
>
> > If you assume two major parties with ~40% of the electorate each, that
>> > means that the 5th seat in each district is noisy -- but it's not
>> > random noise, it's systematically biased by the parties' voting
>> > strategies and the choice of district boundaries.  Larger districts
>> > allow finer-grained Droop quotas and thereby reduce that noise.
>>
>> dlw: Smaller districts engender less opposition from those in power.
>> They keep the constituent-legislator relationship more so.
>>
>
> Absolutely agreed that smaller districts engender less opposition from
> those in power.  That's because smaller districts don't fix the biases that
> keep them in power.
>
> They do maintain the constituent-legislator relationship, *for the subset
> of voters who voted in favor of the legislator*.  For the remaining Droop
> quota of un- or under-represented constituents the nonexistence of the
> constituent-legislator relationship is also maintained.
>

Here's my chance to plug PAL
representation<http://wiki.electorama.com/wiki/PAL_representation>,
which does PR but uses existing-sized districts and preserves a specific
constituent-legislator relationship for all but (up to) one Droop quota of
voters.

>
>
> > >> But if we assume that partial rankings are effective, there's still
>> the
>> > >> strategy/computation tradeoff to deal with: allowing truncated
>> ballots
>> > >> still doesn't help with favorite-betrayal, and STV variants less
>> > >> susceptible to favorite-betrayal are also less susceptible to
>> efficient
>> > >> counting.
>> > >>
>> > >
>> > > dlw: Truncated ballots may not end favorite betrayal, but it'll help
>> with
>> > > it.
>> >
>> > I don't see how; please elaborate.
>> >
>>
>> This is essentially the same arg that IRV does not end the fact that some
>> will still on occasion be pressured to betray their favorite.
>> But it'll be of less consequence when it happens.  It won't be 3rd party
>> dissenters, it'll be the supporters of a major party that does
>> not position itself near the true political center who get pressured to
>> betray their favorite and that in turn will pressure the major party
>> to adapt or die.
>>
>
> Are you saying that favorite-betrayal isn't a problem when those forced to
> do it belong to a major party?  I hope I'm just misunderstanding your
> point, but it sounds to me like you're describing a system like FPTP but
> with major-party spoilers substituted for minor-party spoilers.
>
>
> > >> With an implicit "first-preference" approval, it has the same problem
>> as
>> > >> traditional STV (i.e. IRV), namely of unduly rewarding
>> > favorite-betrayal.
>> > >> With an implicit "all-ranked" approval, the overall system would
>> likely
>> > >> violate later-no-harm with much higher frequency; by expressing a
>> > >> preference between two dispreferred candidates one might
>> unintentionally
>> > >> put the higher of the two in contention.
>> > >>
>> > >
>> > > dlw: I'd say empirically we'd see just how high of a frequency LNH
>> would
>> > be
>> > > violated.  Jameson Quinn had a hard time coming up with a pathological
>> > > example for IRV3/AV3 and I imagine it'd be similar for the above.  The
>> > 1st
>> > > stage would reduce the number of candidates to N+2 and it seems likely
>> > that
>> > > the N+2nd and N+3rd candidates in terms of "all-ranked" approval are
>> less
>> > > likely to be among the N winners.
>> >
>> > Hmm, ok.  I'm operating on the assumption that voters will vote
>> > strategically if doing so is easy, and will vote approximately
>> > honestly if strategic voting is difficult.
>> >
>>
>> okay.
>>
>> >
>> > We're taking the top S+k winners and running some ideal STV method on
>> > them; let's try to find an "easy" strategy.  Here's my idea:
>> > 1) Gather a set of related parties to form a majority-coalition.
>> > 2) Have the coalition propose exactly S+k candidates.
>> >
>>
>> good luck coordinating that..
>>
>> 3) Ask coalition voters to vote for all of the coalition candidates in
>> > any order they choose.
>> >
>> > Since a majority of candidates approve of every coalition candidate
>> > and disapprove of every competing candidate, the coalition candidates
>> > win the approval vote.
>> > By adding the "approval" phase to the STV election, I'm able to turn a
>> > simple majority into a 100% supermajority.
>>
>>
>> > Is there a flaw in my strategy?  (I don't think there is, but I may be
>> > missing something.)  If not, we'll either need to abandon a fixed
>> > limit on the number of candidates or we'll need something more
>> > sophisticated than a simple approval-vote to filter them.
>> >
>>
>> dlw: It's not realistic.
>>
>> You'd need to have serious intra-party discipline to keep the no. of
>> candidates down to S+2
>> and to get a majority of voters all to vote for all of that S+2
>> candidates.
>>  That is a serious coordination problem.
>>
>> But if it did happen then it'd "work" in terms of making the leading
>> coalition of parties cast a broad net that strongly met the needs of most
>> people.  This would be much better than a bunch of non-competitive
>> single-winner elections.  In that case, we're in DINO land.
>>
>
> By "strongly met the needs of most people" you appear to mean "met the
> needs of a bare majority of people marginally better than the
> alternatives".  My concern is that in this scenario 25% of the electorate
> would benefit substantially, 25% would benefit marginally, and the
> remaining 50% would be arbitrarily worse off.  That's essentially the same
> worst-case behavior as the current majority-of-majorities setup, but with a
> simpler strategy required to implement it.
>
> That being the case, I think we'd be better off with small-district STV
> than with large-district STV with this sort of approval-based filtering.
>
>
> > >> It may well be that these issues are all less severe than in the
>> > >> deterministic alternatives to STV, but I still think they're enough
>> to
>> > >> merit consideration of nondeterministic alternatives.
>> > >>
>> > >
>> > > In terms of the US's political culture, nondeterministic alternatives
>> are
>> > > not going to happen anytime in the near future and we need electoral
>> > reform
>> > > ASAP!!!!
>> >
>> > Sadly, I think both nondeterminism and STV share the "not going to
>> > happen in the near future given political culture in the US"
>> > classification, given that US law requires single-winner FPTP
>>
>> > elections for federal representation and the major parties (who
>> > control the legislature and benefit greatly from FPTP) have no
>> > incentive to change that law.
>>
>> dlw: STV need not end 2-party domination.  Reforms that do not end 2-party
>> domination are more fit in the US and should be the only ones pushed.
>> And, as I've shown, it's implementation can be simplified.
>> Thus, it can become a  political jujitsu issue, whereby it is more
>> rational
>> for those in power to accommodate than to resist the proposed change.
>>
>
> The belief that the 2-party system can accurately reflect voter consensus
> relies heavily on the assumption that voters' differences of opinions
> correlate sufficiently well with a single dimension of variability, so that
> tending toward the center along a single axis produces centrist results on
> all issues.  I do not accept that assumption: in my experience, Americans
> disagree along at least two axes that do not correlate perfectly (fiscal
> policy and social policy).
>
>
> > So as far as I can tell the only option for meaningful reform is a
>> > constitutional amendment, and that means reforming 75% of the states
>> > as a first step.  This is not a short-term process.
>
>
>> I think one could argue that the current law requiring single-winner
>> elections is discriminatory twds minorities, and adopted under bad
>> circumstances, and thereby unconstitutional.  This would not require a
>> constitutional amendment.
>>
>
> I think you're perhaps overly optimistic about the willingness of courts
> to overturn election law.  But we'll see - I'd be thrilled to be proven
> wrong about this one.
>
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