[EM] proportional constraints - help needed

[Richard Fobes]

 > 2013/2/6 Richard Fobes<ElectionMethods at votefair.org>:
 >> How many candidates would/could compete for the five (open)
 >> party-list positions?
On 2/6/2013 3:12 PM, Peter Zbornik wrote:
 > Say twenty, for instance.

To: Peter Zbornik

After considerable thinking about your request, I've come up with a 
recommended election method for your situation.

The method has these advantages:

* Uses open-source software that is already available.

* Does not require any modification of the software.

* Provides proportional results for the five seats.

* Provides quota-based representation for women -- which, as I 
understand it, you specified as requiring a woman in one of the top two 
positions, and another woman in the next three positions.

* Is very resistant to strategic voting.

* Produces better representation compared to using STV (single 
transferable vote).

The method consists of running VoteFair _representation_ ranking 
calculations.  Five levels of representation would be requested.  As a 
part of that calculation, VoteFair _popularity_ ranking results are also 
calculated for all twenty or thirty candidates.

The open-source VoteFair ranking software, which runs under either 
Microsoft Windows or Linux, is here:

     http://github.com/cpsolver/VoteFair-ranking

For convenience it can be used in conjunction with the 
Vote-Info-Split-Join (VISJ) framework here:

     htts://github.com/cpsolver/Vote-Info-Split-Join-VISJ

The adjustments to ensure quota-based representation for women is done 
manually, after the calculations have been done.

Here/below is a description of the election method.

Tentatively the five open-list party positions are assigned to the five 
candidates who are ranked as most representative -- according to 
VoteFair _representation_ ranking.

These results are proportional.  And they are very resistant to 
strategic voting.  The details are explained at this web page:

     http://www.votefair.org/calculation_details_representation.html

If the tentative results already happen to meet the quota for women, 
then no adjustments are needed.

If there are no women in any of the tentatively assigned five positions, 
then the two women who are the most popular according to VoteFair 
_popularity_ ranking are moved into positions # 2 and # 4, and the men 
are shifted down.

When the men who tentatively won are shifted down (to make room for the 
two women), their order is preserved (which in the above case means the 
men in seats # 4 and # 5 are completely removed, and the man who was in 
position # 3 is moved to position # 5, and the man who was in position # 
2 is moved into position # 3).

If one or two women won seats in the top five positions, but a woman did 
not reach position # 1 or position # 2, then the more-representative 
woman is shifted into position # 2 and, if necessary, the man in 
position # 5 is completely removed.

In other words, if any woman needs to be promoted, she first comes from 
the tentatively assigned most-representative positions.  Otherwise she 
comes from the highest woman-occupied position in the popularity ranking.

As an example, if the representation ranking looks like this (where 
M=male and F=female) ...

1:  Jiri (M)
2:  Petr (M)
3:  Karel (M)
4:  Vaclav (M)
5:  Eva (F)

... and within the popularity ranking the most popular woman who is not 
listed above is ...

Tereza (F)

... then these are the final results for the party list:

1:  Jiri (M)
2:  Eva (F)
3:  Petr (M)
4:  Tereza (F)
5:  Karel (M)

Why is the second woman moved into position # 4 instead of position # 5? 
  Because presumably half of the Green-party voters are women, and 
presumably you want proportional results if your party should win 4 
seats.  (If the quotas are met without needing any adjustments, then the 
second woman might end up in position # 5, and this would be fair 
because the results imply that quotas are no longer necessary to 
override other political priorities.)

(As a minor point, if in the future the gender-based quota is no longer 
needed because women typically end up in the top five positions, then 
the method for filling position # 5 can be improved by using a method 
from VoteFair _negotiation_ ranking.  In the meantime the tentatively 
assigned winner of position # 5 usually will be demoted, so this future 
refinement would not affect the results under current circumstances.)

Of course you, and your fellow Green-party members, will have questions 
about this method.  I'll be happy to answer them.  Just ask.

Richard Fobes