[EM] Approval vs. IRV

[Juho Laatu]

On 30.11.2011, at 7.23, C.Benham wrote:

> Juho Laatu wrote (29 Nov 2011):

>> I'd like to add that IRV is an algorithm for those that want to favour the large parties. 
> 
> 
> The main thing that favours large parties is legislators elected in single-member districts versus some form of  PR in multi-member districts.

That is pretty much a property of all single-winner methods (when used in that way).

> But yes, IRV is a bit biased towards slightly off-centre
> candidates whereas Approval has a strong bias toward centrist candidates.

I'm not sure if you can say that IRV is biased towards off-centre candidates. If IRV (untypically) elects a minor candidate (with low number of first preferences), that candidate is more likely to be a centrist candidate than an off-centre candidate. If there are three or more major candidates, the the centrists have best chances to win.

(In Yee diagram style simulations IRV easily elects off-centre candidates, but that may often be a result of less first place preferences in the (squeezed) centre.)

Juho