[EM] Fwd: how goes American PR?

[Ted Stern]

The simplest PR system:  open list Approval Transferable Vote.

ATF for multiwinner elections:

Quota ("easy"):  Q = (Nballots + 1)/(Nseats + 1)

A voter may approve any number of candidates.

Each ballot is initially weighted as 1.0.

Count weighted approval totals.  At same time, count weighted
approvals coming from truncated ballots (only one standing candidate
remaining on the ballot).

In each round, seat the candidate with the highest weighted approval
total (T).  The truncated approval total for that candidate is denoted
by L.

The amount of vote used up on each ballot that votes for that
candidate is

       U =  max(Q - L, 0.0) / max(max(T,Q) - L, eps),
            where eps is a small number > 0, say 1.e-9.

This is just (Q - L) / (T - L), restricted to lie between 0.0 and 1.0.

Since truncated ballots will lose their vote completely (and thus the
U factor is irrelevant for those ballots), the truncation factor
adjustment lets untruncated ballots transfer more of their strength.

The rescale factor on each ballot voting for the last seated candidate
is thus

       F = 1.0 - U

Advantages:

ATF is monotonic and Droop-proportional.

Approval ballot is the simplest format.

With multiple winners, Approval strategy for the approval cutoff is
less important.  Voters can simply approve of all candidates that they
feel best represent their positions.

Each round is summable (though the overall election is not), and there
are only Nseats rounds, unlike STV.

The Truncation sum, L, reduces the vote loss that is usually
associated with STV.  In fact, the truncation transfer factor
adjustment could be applied to any quota-based PR method that is
subject to truncated ballot vote loss.

ATF may not be the most ideal PR , but it would be the simplest to
implement quickly.

Ted

On 03 Dec 2011 14:31:16 -0800, Jameson Quinn wrote:
>
> I left out one of the most important advantages of PAL voting: that it's dead
> simple for voters. Though you can vote a more-expressive ballot if you want to,
> a simple bullet vote is enough to give good, proportional but not
> party-centric, results.
>
> Jameson
>
> 2011/12/3 Jameson Quinn <jameson.quinn at gmail.com>
>
>     Does "American PR" have a specific meaning yet? I'm sure I'll be in favor
>     of it, whatever PR variant it is; but while I'm still ignorant, let me
>     guess a little.
>    
>     I doubt it's a mixed-member system. They're good, but the US, despite (or
>     perhaps because of) being one of the most partisan countries around, has
>     too much suspicion of "party machines" for that to catch on.
>    
>     So that leaves ... I guess the most-probable options are global STV or STV
>     in small multimember districts (3-5 members).
>    
>     Again, these are both quite good systems I'd support. But if it's not too
>     late to offer a suggestion... I'd strongly encourage you to consider
>     something like PAL representation. It's certainly not the simplest system
>     there is, but then no PR system is really simple. And as advantages you
>     get:
>     -- High potential for 100% continuity (if the statewide gerrymander was
>     fairly proportional, and if third parties don't pick up any seats). This is
>     a HUGE advantage when selling to incumbents. I mean, seriously, tremendous.
>     -- Voters and/or peers have the real power to remove even the most
>     well-encrusted incumbent if they sour on him or her. That is, it's
>     voter-centric, not party-centric
>     -- Almost every voter gets their own local representative WHOM THEY VOTED
>     FOR. This is absolutely something that would resonate with US voters,
>     raised on tales of "No taxation without representation".??
>    
>     Check it out.
>    
>     (And yes, I think that we can work together over PR, even if we don't see
>     eye-to-eye on single winner systems.)
>    
>     Jameson
>     2011/12/3 David L Wetzell <wetzelld at gmail.com>
>
>         American PR is a coming. ??You must decide if you want to keep
>         quibbling over the best single-winner election rule or push hard for a
>         better mix of multi and single-winner election rules in the US.
>        
>         dlw
>         ---------- Forwarded message ----------
>         From: Rob Richie <rr at fairvote.org>
>         Date: Sat, Dec 3, 2011 at 11:05 AM
>         Subject: Re: how goes American PR?
>         To: David L Wetzell <wetzelld at gmail.com>
>
>         A little slow in getting our American PR-like plans drawn, but we'll
>         have them done for hte whole country in early 2012 and heat up in our
>         outreach... getting some related opeds.
>        
>         Next year should be a good one for the idea -- ??lots of chances to
>         talk about it.
>         Rob
>
>         On Wed, Nov 30, 2011 at 12:26 PM, David L Wetzell <wetzelld at gmail.com>
>         wrote:
>
>             I wonder if tea-partiers unhappy w. the Republican party might get
>             in on it?
>            
>             dlw
>
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