[EM] PR-STV and vote management

[Jonathan Lundell]

Meek's method elects A, C1 & C2 in this example.

On Apr 19, 2007, at 10:18 AM, raphfrk at netscape.net wrote:

> I was thinking about an easier solution to the vote management  
> problem.
> This is where it is sometimes in a party's interests to try to  
> split their support
> equally between two candidate due to exhausted ballots.  In effect,  
> they
> get a candidate elected without a quota.
>
> For example, assume a 3 seat election and 4 candidates.
>
> 12500: A
> 9000: B
> 18500: (C1,C2)
>
> Voters might vote
>
> 12500: A
> 9000: B>C1>C2>A
> 12000: C1>C2
> 6500: C2>C1
>
> Quota is 10000 (approx)
>
> Round 1: A is elected, all his votes are exhasted
> A: 12500 *
> B: 9000
> C:1 12000
> C2: 6500
>
> Round 2: C1 is elected and votes transfer to C2
>
> A: 10000*
> B: 9000
> C1: 10000*
> C2: 8500
>
> B then wins the last seat as C2 is eliminated.
>
> However, if C1 and C2 had evenly split their 18500 votes, they  
> would have won both
> seats as they would have had 9250 votes each and B would have been  
> eliminated first.
> This causes parties to participate in 'vote management', the effect  
> of which is that it is
> no longer tactically correct to just rank the candidates in order  
> of your choice.
>
> The best solution would be to re-calculate the quota after each  
> round.  However, this
> would greatly complicate the counting process (especially if it was  
> hand counted).
>
> However, really all that is needed is to recalculate the quota once  
> at the end.
>
> The rule would activate when
> a) there is no candidate with a surplus to distribute
> b) the number of uneliminated candidates is one greater than the  
> seats to allocate
>
> The quota is recalculated and surplus transferred to one of the  
> remaining
> 2 unelected candidates.
>
> Round 3 would change to:
>
> Quota recalculated: (10000+9000+10000+8500)/4=9375
>
> A: 9375 (transfers 625 and they exhaust)
> B: 9000 (below quota)
> C1: 9375 (transfers 625 to C2)
> C2: 9125 (625 transferred in)
>
> Ideally, this should be repeated until it converges.  In fact, it  
> is probably
> relatively easy to work out mathematically what the final result  
> would be
> without actually counting the additional rounds.
>
> Anyway, the result is that C2 has more votes than B and is thus  
> elected.  This
> eliminates the tactical benefit to voters who participate in vote  
> management,
> which allows them to be honest.  It has the additional benefit that  
> all elected
> candidates represent the same number of voters (at least all the  
> ones who
> come from the same district).
>
> Raphfrk
> --------------------
> Interesting site
> "what if anyone could modify the laws"
>
> www.wikocracy.com
>
> Check Out the new free AIM(R) Mail -- 2 GB of storage and industry- 
> leading spam and email virus protection.
> ----
> election-methods mailing list - see http://electorama.com/em for  
> list info

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.electorama.com/pipermail/election-methods-electorama.com/attachments/20070419/b143c863/attachment-0003.htm>