[EM] Martin's Sixty-Forty Split Districts:
Craig.LAYTON at add.nsw.gov.au
Tue Apr 3 17:47:38 PDT 2001
Martin wrote (in part):
>Thus in both cases the sum is more proportional than the sum of its parts.
>particular, the five seat districts create a more proportional council,
>being individually much less proportional than the four seat districts.
>I've tried to make this example a little less extreme than the previous one
- at the
>expense, sadly, of simplicity.
The simplest way to think about it is in terms of 1 person electorates or 2
person electorates. 2 person electorates will elect the same number of
people (1 from each party) whether the support is 30%-70% or 50-50. With a
significant number of 1 person electorates, the number of reps will tend to
be closer to the proportion of support. It's a law of averages thingy.
>Whether, in general, it is better to have odd or even numbers of seats in
>district is beyond my ability to determine - but Layton appears to be able
to do so,
>and claims that odd numbers of seats will give a more proportional council
>general. Perhaps you should check out what he has to say?
I should point out that odd numbers will only be more proportional if you
have a two party system and a small number of members per district. But STV
districts are rather mercurial; throw in a few strong minor parties and
independants and all your calculations fall to bits. For instance, with a
single strong minor party (three party support ratio 40:45:15) you would
probably get a more representative legislature from six member districts
than with five or seven.
I say odd numbers because it appears that on average, they wind up being
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