[EM] Testing 1 2 3

James Gilmour jgilmour at globalnet.co.uk
Fri Jan 2 16:38:01 PST 2004

> Basically the idea was to attempt to generate a realistic set 
> of votes (one where voters vote principally but not entirely 
> on a single ( left-right ) dimension) and then calculate the 
> results under a variety of different methods to see how they 
> differ.

David, thanks for specifying some of your proposed test criteria.  I can now see some of the
questions you wish to address.  But you still won't be able to address some the big issues in
practical electoral reform, like the trade-off between proportionality and localness of
representation in setting district magnitude.  This is a major issue here in Scotland right now as
we take forward a Bill to introduce STV-PR for our 32 Councils.

> The model can generate other sets of votes based on 
> other realistic scenarios and also (IMHO) completely 
> unrealistic scenarios. 

I think there is another very real problem here.  It is not clear from your original post whether
your model will modify the voting patterns under the 11 different voting systems, but my reading
would be that it would not.  We know from practical experience that real voters do change their
voting patterns when you change the voting system.  And they do some very strange things with
systems like MMP (= "AMS" in UK), most probably as a result of ignorance.  We can also see them do
some very positive things with MMP to achieve minor party representation.  I don't know how you
would begin to model that at all realistically.

> STV was the most problematic system to model and the one I'm 
> least happy with.

You don't say what the problems were, but STV-PR is conceptually very different from all the other
PR systems and so there are special issues in modelling voter preferences.

It won't help your exercise, but we do now have access to three full sets of STV-PR preferences of
real voters in real elections, from the Dáil Éireann election in 2002.  These three files are
available on the web.  But of course, they are of no use to model any other voting system because
the voters would have voted differently had the system not been STV-PR or had they not faced the
three particular combinations of candidates in those three particular political situations.


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