[EM] PRfavoringracialminorities

[Kristofer Munsterhjelm]

Raph Frank wrote:
> On 8/22/08, Kristofer Munsterhjelm <km-elmet at broadpark.no> wrote:
>>  Having different amounts of voting power would simplify multiwinner
>> election systems considerably. One could, for instance, just do a FPTP count
>> and then elect the n highest scoring, giving them voting power equal to the
>> share of the total vote they got.
>>
>>  Still, that doesn't happen, and no assembly is set up that way. Why? Does
>> it seem too unfair?
> 
> It makes things more difficult in the assembly.  It is much easier to just have
> to count the Yes and No members.  With modern technology, it would be easier.
> Alot of assemblies have an electronic means for legislators to vote.
> The computer
> could just add up all the weights.
> 
> There are problems with single members have to much power, but that is
> covered by putting an upper limit on the allowed power.
> 
> A PR-STV count could be run with a max votes allowed (say double the
> Droop quota) and then just keep eliminating the lowest candidate until
> the correct number of candidates are left and only transfering surplus
> above the max votes limit.
> 
> This upper limit might not even be needed if candidates are restricted to
> one constituency.  In Ireland, getting more than 2 quotas is
> extremely rare.
> 
> I think keeping the elimination rule is still a good idea
> as it allows people vote for outsiders while still allowing their vote to count
> for somene who is elected.

I agree. This means that "complex" proportional representation schemes 
may have their place even for weighted vote situations. I also think 
it's possible to transform an arbitrary weighted vote constrained-power 
PR system into a party list PR system. The transformation is simple: 
party list is just an election of parties where the parties have 
different "power", and then that power is translated into representative 
power with equal votes per representative by varying the number of 
representatives.

There are some limits to the transformation: for instance, you can't 
have representation below 1/(assembly size), thus the "power constraint" 
caveat of the transformation. Similarly, power is in steps of 
1/(assembly size), and you can't have a sum power (over all 
representatives) higher than 1 (which is to say, the assembly can't hold 
more reps than its size).

But if it's true that a simple "FPTP then pick the n best" is a bad 
system for electing representatives with different power, and I'm right 
about the transformation, then it follows that ordinary list PR (which 
is just a FPTP vote for parties) can be a bad system as well. The STV 
analog would be one where voters can rank parties and then transfers are 
done (in some way, I'm not clear how) before translating party power 
into the number of representatives (usually by Webster).

If constituencies are too small and there's no national compensation, 
then list PR could suffer from the same problems as exist with FPTP 
applied to candidates: vote splitting and the familiar "worst of many 
evils" situation. Party list PR elections usually lead to multiparty 
democracy, though, so I am guessing that this effect isn't significant 
for real world party list districts. It can still be annoying, in 
particular to voters who are dissatisfied with existing parties but know 
that voting for a new party is "just throwing one's vote away".

If we package this up into a more general observation, I think it's the 
case that parties can survive if it only takes k% (for some unknown 
value of k) to be represented. If the method's effective threshold is 
greater than k%, you get two-party rule, and if it's less, you get 
multiparty rule.
For single-winner FPTP, even without gerrymandering, the effective 
threshold can be very high, effects of which we all know, but with party 
list PR, the effective threshold is low and so multiple parties survive.

Again, it's not this simple in reality, but it's a good approximation. 
Some countries that have FPTP in single-winner districts have managed to 
keep multiple parties alive (India is an example, I think), and some of 
this can be attributed to regional differences where a party may be 
significantly stronger than its national share in some areas of the 
country, thus saving it from extinction of going below k%.

> If only 2 ranks were allowed, this would allow each constituency to
> announce its full results as a 2-d table, while still giving proportionality.
> 
> Voters would be recommended to vote for a candidate who is likely
> to get elected as their 2nd choice.

I seem to remember past posts on this list about so-called "three slot 
methods" that would have only two ranks, but approval-like ordering 
within each rank. Perhaps these could be generalized to multiwinner 
methods as well. I know of a few multiwinner Approval methods: 
proportional approval voting as well as the "approval = max, disapproval 
= min" conversions of multiwinner Range methods like RRV and LPV0+. 
Neither PAV nor LPV0+ do very well in my simulations, though; badly 
enough that I at first wondered if I'd coded them incorrectly (and that 
I'm still not entirely sure).

If Range or Approval are good single-winner methods, then "pick n 
highest scoring" for Range and Approval may be good weighted multiwinner 
methods. Cardinal-3 (with +1, 0, -1) could work; inasfar as CR/Range 
resists cloning, so would these methods handle the problems noted above 
regarding FPTP party list PR (or FPTP-based weighted power multiwinner 
elections).

Condorcet could also be used as a weighted-power method, but only if it 
gives scores and not just ranking for its social ordering. Perhaps an 
eigenvector method?