[EM] electoral methods - US and Europe

[Adam Tarr]

James Green-Armytage wrote:

>         Do you realize the extent of the theoretical unsoundness of 
> Saint-Lague
>and Hare? I was convinced of it by an example which James Gilmour gave
>last July. Here is a link to the posting which contains that example:
>http://lists.electorama.com/pipermail/election-methods-electorama.com/2003-July/010368.html

That example only speaks to Hare, not Webster.

>         I would say that Saint-Lague systematically favors smaller 
> parties, and
>while I'm all for smaller parties, I don't think that this is a good way
>to go about giving them a bigger role, because it introduces a paradox of
>more people gaining fewer representatives,

Not really.  Both Jefferson and Webster try to minimize the error between 
perfect proportionality and the actual representative allocation.  The 
difference is that Jeffeson only considers under-represenation an error, 
whereas Webster considers both over-representation AND under-representation 
as an error.  Adams only considers over-representation as an error.

>  along with an incentive for
>parties to split themselves up into smaller chunks for purely strategic
>reasons.

This, however, is true - Webster does create incentive to split up parties, 
in certain situations.  Here's one: there are 4 seats to be filled. One 
faction has 1203 voters, and the other faction has 1200 voters.

Faction 1 votes for all four of its candidates with every vote.
Faction B splinters itself into three parties, and has the voters split up:

1200 party 1
401 party 2a
401 party 2b
401 party 2c

In this fashion, they get three positions in stead of the proper two.  This 
sort of splintering can produce erratic results in borderline cases like 
this, so it's not always a good idea.

My conclusion is that in situations where manipulation is not an issue 
(such as deciding how many representatives each state gets) Webster is a 
better choice, but in situations where splintering and voter coordination 
is possible, its better to avoid the problem by using Jefferson.  Still, 
being able to pull off this sort of manipulation is pretty rare.  Webster 
is a very good allocation

>I've read Lijphart and I think he was wrong about this.
>         I think that the best way to help smaller parties in a proportional
>representation scenario is to use an STV system so that there is no risk
>of people "wasting" their votes on small parties with not quite enough
>votes. Also in some cases the votes transferred from an eliminated small
>party candidate may go towards helping another small party candidate to
>win a seat.

You should also consider proportional approval voting (PAV), which has 
those properties as well.

>         As for seat apportionment by state, I admit again that I'm not an 
> expert
>in it. You're saying that the U.S. now uses a Saint-Lague divisor? I live
>in the U.S., and I didn't even know that.

As others have said, it uses something altogether different - I think they 
should switch to Webster.  The method they use is very similar to Webster, 
but it *slightly* favors small factions.