[EM] Preferential voting system where a candidate may win multiple seats

[Juho Laatu]

On 18.7.2013, at 14.15, Vidar Wahlberg wrote:

> the percentage of the votes the party received in the
> district that plays a role

This expression is actually ambigious. It could mean percentage of the votes of the district votes or percentage of the votes of the party votes.

> It could be an idea to implement an algorithm that tries to minimize
> "partySeatsInDistrict / seatsInDistrict - partyPercentageInDistrict" for
> all parties in all districts, but I believe this is a fairly difficult
> problem to solve, and the algorithm would likely be complex.

Algorithms that aim at ideal results may be complex. Simpler approximate algorithms may give almost identical results. Ideal algorithms have the benefit of being provably ideal in some sense. Simple algorithms have the benefit of being understandable to the voters (and of course also easy to use and verify).

> I do feel that distributing first seats to small parties first makes
> more sense, especially considering that certain small parties (such as
> "Rødt") got a lot of support in districts with large cities, but nearly
> no support in other districts. They should be "guaranteed" to receive
> their won seats in the districts where they got most support.

I think it is ok to simply distribute first all seats of the smallest party, then all seats of the next smallest party etc. This is to avoid any weird results where some parties got seats in districts where they had relatively small support. Large parties do have strong candidates in every district, so leaving the "rounding errors" to them causes least harm.

> and I believe it's
> important that the method is so simple that most people can easily grasp
> it.

Yes, this is quite important. Although I note that also the philosophy of a complex algorithm that aims at ideal results (in some mathematical sense) may sometimes be easy to explain to the voters, although the actual algorithm might be very complex.

Most voters will not learn how to count the results anyway, but most of them like the system more if they at some level can trust that it is fair. This could mean exparts saying that it is good, media and friends saying that it is good, or simply nobody complaining that it has some bad features (like paradoxical results or a complex algorithm that may hide something).

> I think you may have misread the line you quoted.

Yes, that was just confusion and being too quick to push the send button.

Juho