[EM] real world 9-winner election using RRV

[Jameson Quinn]

2011/6/25 Kristofer Munsterhjelm <km_elmet at lavabit.com>

> 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:


Wait.... is that a global randomization, used across all votes? If it is...
or in fact, even if it isn't... I suggest you do what Warren suggested, and
run it several times, with different random seeds, to see if the results are
reasonably stable.


>
>
> {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
>

Heh. As I suspected, STV came up with the same list as AT-TV.


> {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,
>

Those results also look much more reasonable to me.


>
> 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!
>
> I know the feeling.
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