[EM] STV+AV

[David L Wetzell]

>
>
> ---------- Forwarded message ----------
> From: Bryan Mills <bmills at alumni.cmu.edu>
> To: David L Wetzell <wetzelld at gmail.com>
> >>> >
> >>> dlw: If the number of possible rankings is the number of seats + 2 then
> >>> it's not too bad.  And nobody would be forced to rank umpteen
> candidates,
> >>> so the low-info voters could just vote for their favorite candidate.
> >>>
> >>
> >> The number of possible rankings is quite a lot larger than S+2.  Even if
> >> you don't transfer votes from elected candidates, there are still C-S
> >> candidates eliminated -- so you'd have (C choose C-S-1)*(C-S-1)!
> >> distinguishable rankings, and even more if you allow equal rankings.
>  The
> >> only way out seems to be to pre-filter the set of candidates, so you
> >> basically have to drop to approval voting at some point --
> >> candidate-registration petitions and the like -- and then we're back to
> an
> >> arbitrary cutoff.
> >>
> >
> > dlw: You misunderstood me.  If voters are only permitted to rank S+2
> > candidates then it's not as bad for voters.
>
> I don't see how arbitrarily reducing voter options is "not as bad for
> voters"; especially if S is small, only allowing one to rank S+2
> candidates seems like it would result in either frequent undervotes or
> an increase in the need for strategic compromise-ballots.
>

dlw: Voters wd not be expected to rank everyone.
It takes seriously the fact that there are limits to voter rationality and
understanding of candidates.
Besides, with STV, the lower-ranked votes are less likely to count anyways
and so it seems another case of making a mountain out of a molehill,
or holding to what is theoretically pure vs what is practically useful.

Yeah, voters might vote strategically for their 5th or 7th ranked candidate
if they are not permitted to rank the umpteen candidates in an election...

If that disturbs you greatly, relative to the many other serious electoral
reform issues then something is wrong.

>
> >> Partial rankings might be workable in a weighted-seat STV variant,
> though.
> >>  If a vote only transfers in case of elimination (and not in case of
> >> surplus), one would only need to rank candidates down to the first
> >> candidate sufficiently likely to be elected, and you could split the
> ballot
> >> into manageable chunks by party.  Determining a suitable cutoff
> candidate
> >> still has a cognitive cost, but it probably wouldn't be that bad in
> >> practice.
> >>
> >
> > 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.

>
> 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.

And, I myself support 3-5 seat STV w. Droop quotas for US congressional
elections,

but for state representatives, I prefer 3-seat LR Hare, with the Hare Quota
that uses the state senate districts for the election of 3 state reps.

 We don't need rankings for state reps elections that on average attract
less voter attention.

>
>
> >> 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.

If you don't let people rank all of thee candidates, they might, in
addition, not vote for their true 5th or 7th favorite candidate.  But this
is small potatoes, since in practice most of the time the lower ranked
votes are not consequential with STV.  But with STV+AV, it would still help
to decide who is among the S+2 finalists.

>
>
> >> > The STV variants that are less strategy-prone are computationally
> >>> > inefficient, and even those are not strategy-free.
> >>> >
> >>> > And perhaps most importantly, the more resistant an STV method is to
> >>> > strategy, the more complicated it is to explain and understand.
> >>> >
> >>> > As deterministic methods go, I do like STV methods; but DS fixes a
> lot
> >>> of
> >>> > the worries I have about them.
> >>> >
> >>> dlw: One could also apply the same sort of approach to simplifying STV
> >>> with the
> >>> initial treatment of all of the rankings as approval votes to get the
> >>> number of candidates down to N+2, where N is the number of seats.
> >>> As with IRV, it's easier to explain STV when there's relatively few
> >>> candidates to eliminate.  And, it'll mitigate the strategy effects,
> which
> >>> have to be examined more closely.
> >>
> >>
> >> The initial treatment of rankings as approval votes introduces some
> other
> >> problems, though.
> >>
> >> With an explicit "approval threshold" in the ranking, it induces a
> >> substantial cognitive cost on the voter (determining the approval
> threshold
> >> strategically).
> >>
> >
> > dlw: Once again, if the no. of seats isn't that great then they'd not
> have
> > to sweat it too much.  Do I rank 1, 2, 3 or 5 candidates?  Who can I live
> > with?I'd say it's an empirical question whether such would be a
> reasonable
> > demand on voters.  And I'd reckon they'd get the hang of it with some
> > practice...
>
> The question of how many candidates to rank isn't a function of the
> number of seats, it's a function of the number of candidates.  Even
> with only 5 seats, you'd still need to either compromise your vote or
> rank all of the candidates between your most-preferred and a
> front-runner.
>

But the no. of candidates tends to correlate with the no. of seats and so
the heuristic of tying the rankings to the no. of seats could work
and it could also help to reduce the number of candidates, which wouldn't
be a bad thing for voters with a limited amount of time to
learn about the issues and candidates.

And arguably, people will adapt to the best they see fit doing with the
options given to them.  The issue is the severity of the tradeoff between
the truncated ranking and the benefits gained from simplification of the
ballot and reducing the no. of candidates to S+2 in one fell swoop.

>
> That is, the problem is in reducing the candidate pool, not reducing
> the number of seats.
>

But fewer seats lead to fewer candidates, as also does a truncated ranking
system that is used to reduce the pool dramatically.

>
>
> >> 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.

>
> >> 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.

>
> 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.

>
> That being the case, I'd rather look for systems that are likely to be
> unambiguously successful at the state and local level rather than
> compromise-reforms with unclear benefits.
>

I agree w. pushing for reforms at the state/local level, but also think
that 3-5 seat American forms of PR are worth fighting for, since they
strike at the key problem of how the US's system too easily tilts to
effective single party rule.

>
> dlw
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.electorama.com/pipermail/election-methods-electorama.com/attachments/20120202/1e033901/attachment-0004.htm>