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Dear John,
<blockquote TYPE=CITE>
<pre>approval and ranked pair are not as described proportional methods,
but you are right they could be used as inner motor to produce
proportional methods.
However, you have to be careful about how you do this.
The key into converting a single-winner method into a motor for
a proportional multiple-winner method is to make them able to produce
weights as an output. Why? Because of fairness issues: first a system
needs to be fair between parties, next between candidates and finally
between voters. It is one thing to have a single-winner method that
avoids vote-splitting, does not favor cloning and gives an equal power
to every voters
(wheter approval fits or not is not the debate here), it is another
matter to preserve those
qualities while
building your proportional model using such a single-winner method.
For examples, take approval and let`s use it as you said to build a
proportional model. It is
obvious that it would introduce a bias toward parties with the same
program or alike.
Imagine all ridings with 3 parties at first, each with a 33% support.
Then one of the party
(Liberal for example) would split into three others over a detail,
presenting 3 candidates
for each riding. Instead of approving only my liberal candidate I would
approve all three
candidates. So the final support toward every party would now be
measured as 20% for
every party. Clearly the fractional support
becomes dependent of the number of candidates using such a method...</pre>
</blockquote>
Now about fairness between candidates. Two main problem rise: first some
particular candidate will be compared against which other candidates of
the same party.
<br>All of them or only the ones running in the same riding? If you want
to compare some
<br>candidate with the other of the same party running in other ridings,
you assume that ridings are equivalent in composition (poor/rich, urban/rural,
language, religion,...) so to compare supports as a measure of the candidates
quality. If you don't you will see some fights to run
<br>in the well-known fortress of a party: bias again (this already exist
with FPTP). Some will say ok let's just compare with the candidates of
the same riding, typically STV does that.
<br>Now the comparison is fair, but still the candidacy fight still creates
a problem. In Ireland,
<br>political scientist report huge attempt not only to get a specific
riding, but especially to have bad co-runners.In other words, with STV,
running in the same super-riding than your party leader, you need your
party to elect two seats in order for you havind the second... So your
election is favoured if the other candidates of your party in the same
riding than you are bad, and you are disfavoured if they are all the good
candidates of your party.
<br>So fairness between candidate needs ridings equivalent in composition
so to compare
<br>between ridings. One way of obtaining this is a sampling technic, that
would use equivalent
<br>sample of the electorate instead of geogrphical ridings. In SPPA, I
suggested to use birth date (day, month, modulo of the year) to build such
virtual ridings. Another way is using one single huge riding, but then
the candidate list is humonguous and voters are less interested...
<p>Finally, fairness between voters. This is mainly assured by the single-method
itself.
<br>Wether(?) you think Condorcet favours center-voters or FPTP favours
old parties or Cardinal Rating favours extremist parties, the proportional
system resulting will be as fair as the original single-method. For example
vote-splitting problems of FPTP would end up
<br>into a very fractured representation in the house. The other fairness
issue to ensure is that every vote counts with the same weight, so ridings
(virtual or not) should be made with equal population size... Again
SPPA fits. Finally such a system can elect several MP's in some riding
and none elsewhere. Some voters would perceive this as unfair. I think
they would be rigth in the case of geographical ridings? Do you?
<p>Steph.
<br>PS: If you are interested SPPA on fairvote canada's site deals
<br>with such issues...
<br><A HREF="http://www.fairvotecanada.org/phpBB/viewtopic.php?topic=8&forum=1&4">http://www.fairvotecanada.org/phpBB/viewtopic.php?topic=8&forum=1&4</A>
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