[EM] real world 9-winner election using RRV

[Kristofer Munsterhjelm]

Jameson Quinn wrote:
> 
> 
> 2011/6/25 Kristofer Munsterhjelm <km_elmet at lavabit.com 
> <mailto:km_elmet at lavabit.com>>
> >   So I quickly hacked together something to run it through my old
> >    multiwinner code, but I'm getting unusual results. Could someone
> >    check that they get what I'm getting?
> > 
> >    {C101 C102 C103 C104 C105 C106 C108 C109 C110} for birational voting
> >    {C101 C102 C103 C104 C105 C106 C108 C109 C110} for Range PAV (integral)
> >    {C101 C102 C103 C105 C106 C108 C109 C110 C116} for STV
> >    {C103 C106 C108 C109 C110 C111 C113 C115 C116} for Meek STV
> >    {C103 C106 C109 C110 C111 C113 C114 C115 C116} for Schulze STV
> >    {C103 C106 C109 C110 C111 C113 C114 C115 C116} for QPQ
> 
> 
> How are you handling ties in the STV methods? Just eyeballing it, it 
> seems that your results are skewing towards the high-numbered candidates 
> (who, in this election, seem to be weaker candidates - perhaps the 
> ordering is in the order that they submitted statements, so the 
> least-organized candidates come last?). And when I look at your ranked 
> inferences, you do indeed put the highest-numbered candidate first, so 
> I'm wondering if you're actually (mistakenly?) using "lexically-last" as 
> an arbitrary tiebreaker for ballot equalities.
> 
> Again, that's just from eyeballing, so I could be wrong.

I thought I was using the method of first difference as a tiebreak, but 
apparently not. That method breaks the tie in favor of the candidate who 
first has a higher score.

So I made a randomization preround (permuting the candidate-number 
assignment instead of assigning 0 to C101, 1 to C102 etc), and the 
results changed:

{C101 C102 C103 C104 C105 C106 C108 C109 C110 } for birational voting
{C101 C102 C103 C104 C105 C106 C108 C109 C110 } for Range PAV
{C101 C102 C103 C104 C105 C106 C108 C109 C110 } for STV
{C102 C103 C104 C105 C106 C107 C109 C110 C116 } for Meek STV
{C102 C103 C104 C105 C106 C107 C109 C114 C116 } for Schulze STV
{C102 C103 C104 C105 C106 C107 C109 C110 C116 } for QPQ,

so there seems to be a lot of ties for the ranked methods to deal with. 
In retrospect, it makes sense, because there weren't enough ratings for 
voters to be able to rate every candidate uniquely.

Well, that's what I get for using old code whose limits I've forgotten, 
I suppose!