[EM] Sainte-Lague vs d'Hondt for party list PR

[Juho Laatu]

On 2.7.2012, at 8.16, Michael Ossipoff wrote:

> That's _big_ bias in favor of large parties, and against small parties.

Maybe so, if you count the s/v values for D'Hondt. If you count the seats, the bias will be less than one seat per party. That's maybe not a "_big_ bias". (Sainte-Laguë is however even less biased on average, and stays below the one seat bias limit in most cases.)

> Yes, even in that small district, d'Hondt's bias will of course make things worse for small parties. But d'Hond't effect will be less in the small district, even as the small district problem makes things worse, in its own way, for small parties.

I simply summed up the expected D'Hondt biases of the multiple districts. The biases of small districts may easily sum up to multiple seats per party (= higher than with one large district). Although D'Hondt in some sense allows large parties to get seats easier in one large district, splitiing the districts in several small districts is probably strategically even better for them.

> You said:
>  
> But for most purposes already methods that guarantee a small party its first seat if it gets 1/N of the total votes (where N is th number of seats) may be good enough (people may not fear too much losing their vote when they vote for the small parties).
>  
> [endquote]
>  
> I didn't know that. Guaranteeing a seat for a Hare quota, no matter what the party's divisor-quotient is, would help avoid the split vote problem. On the other hand, suppose that the small party that thereby gets in happens to be the most abominable party there is, from your point of view. Do you really want to give them a seat by a special rule that violates the PR rule that allocated the other parties' seats? Do you really want to give that maximally abominable party a significantly higher s/v than your party, and the other ok parties? I don't think so. l don't like that, and neither would you.

Many competitive voters hate also other competing large parties and every seat they get. Some of the small parties could be even more disliked. But personally I'd welcome almost any such representative to the parliament. There have been arguments about the risk of fragmenting the parliament if one lets all the small groups in. But at least in my home country I can't see any harm done if one would allow one person from the "elders' party" and one from some far left communist party. No harm done. Better proportionality. All voters (with one quota of supporters) would be represented as they want to be represented.

> The inhibition against honest voting, with d'Hondt is similar to that in FBC-failing single-winner methods.

But isn't there also a risk when voting for small parties in Sainte-Laguë? (just smaller and not in favour of large parties) I mean that it is not easy to extend FBC and keep the definition exact but make it such that it would cover D'Hondt but not Sainte-Laguë.

Juho