[EM] Two means of proportionality

[Kristofer Munsterhjelm]

I think I see the difference between the proportionality divisor methods 
try to achieve and the proportionality that largest remainder methods 
try to achieve.

The largest remainder methods define their proportionality as quota-wise 
proportionality: a given group should at least get its quota's worth of 
seats, no matter what.

On the other hand, the divisor methods (at least Webster/Sainte-Laguë) 
try to attain an ideal reflection of a certain probability distribution 
whose parameters are given by the votes. For instance, in Sainte-Laguë, 
this distribution is approximately a multinomial distribution, where the 
probability for a party being drawn is equal to its proportion of first 
place votes. In a sense, these produce the "most fair random result", 
like what you would get if you drew at random, but if you could exclude 
those that happened to be too extreme due to bad luck.

I say "approximately" becauses, the outcome produced by Webster 
optimizes the chi-squared metric (Sainte-Laguë index), which AFAIK only 
asymptotically gives the most likely rendering of the multinomial 
distribution.

(This also points to a relation between lotteries and highest-average 
methods.)

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So if we were to make a ranked ballot version of Sainte-Lague in a less 
hackish way than my CPO-SL v2, it should retain that logic of trying to 
ideally represent some kind of distribution.

For Condorcet, that gives two possible strategies:
	a. Find some kind of distribution/model that can solve the sliver 
problem, then use this as a base method for a CPO-style "exclude all not 
in either matchup" method to fix the problem of later votes being 
concealed by earlier ones.
	b. Find a distribution that, when we ideally represent it, gives a 
Condorcet outcome in the single-winner case and a multinomial 
distribution when everybody plumps for a single party.


The first may be easier, while the second would be more axiomatic (i.e. 
more "elegant" in being from first principles). I'm not a good enough 
statistician to really do either.

A related way of looking at it might be to consider whether the problems 
that we get when applying Sainte-Lague to small seat sizes can be fixed 
by trying to accurately represent something else than fractions of first 
preferences, or whether no matter what strategy we pick, we'll have to 
use another method to deal with the quantization to a small number of seats.

If it can be fixed by accurately representing something else, alone, 
then that suggests approach b. If it can't, then that suggests approach a.