Talk:Proportional representation

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Clarity

User:69.172.158.251 I pressed Enter accidentally:

It's not a "citation needed" tag; it's a "clarify language" tag.

"Conversely, no system has no Proportional Representation since metrics" is confusing to me. — Psephomancy (talk) 15:53, 13 February 2020 (UTC)

I think he's saying "There's no score that tells you if the outcome is proportional or not, so there's no way to know if the outcome is proportional". A better way of saying it might be "every method maximizes its own measure of good". Kristomun (talk) 16:31, 13 February 2020 (UTC)

You guys are both missing it. There are measures of PR like Ghalliger for example. They will never reach any where near the maximum level of disproportional even in single member plurality. The most disproportional systems are moderately proportional under all metrics. To get literally zero representation you have to elect a whole parliament from parties that nobody voted for. This is clearly never going to happen. I thought this was obvious but if you can write it more clearly please do so. --Dr. Edmonds (talk) 00:22, 14 February 2020 (UTC)

PR majority criterion

topic copied from User talk:Psephomancy at 21:11, 19 April 2020 (UTC) by RobLa (talk)

I was on German Wikipedia, and found this article (https://de.wikipedia.org/wiki/Mehrheitsbedingung) which, if you look at it in Google Translate, discusses a criterion that a majority must always win at least half of the seats in a multi-winner election (the Google translation calls it the "majority condition"). I've often wondered if there is an English equivalent; do you know of any such thing? BetterVotingAdvocacy (talk) 07:08, 17 April 2020 (UTC)

No, I'm not very knowledgeable about PR. — Psephomancy (talk) 02:12, 18 April 2020 (UTC)

This seems like a good question for User:Kristomun. Is there an English equivalent of w:de:Mehrheitsbedingung? -- RobLa (talk) 21:16, 19 April 2020 (UTC)

The criterion says that a party that gets a majority of the votes must also get a majority of the seats; it's a special case of the quota criterion. D'Hondt meets it, but Sainte-Laguë/Webster does not, and in any case, it may be failed due to districting problems. I vaguely recall there being some uproar in Malta over just this. See https://aceproject.org/main/english/es/esy_mt.htm (search for "In 1981"). In any case, I don't know of any English term for that criterion, and I would guess there probably isn't one because party list is neither used in the UK, the US, or Canada. If I had to translate the term, I'd call it something like "majority lower quota" or "majority quota criterion". (The corresponding "minority upper quota", that a minority of the votes can't give you a majority of the seats, is the w:de:Minderheitsbedingung. They're distinct in the case that e.g. no party has a majority: the majority quota criterion doesn't apply in such a case, but if one of the parties get a majority of the seats, then that violates the minority quota criterion.) Kristomun (talk) 21:51, 19 April 2020 (UTC)

Is this not the Hare Quota Criterion? This is the one I have seen most referenced as the multimember version of PR. --Dr. Edmonds (talk) 02:44, 20 April 2020 (UTC)

To guarantee that a majority of voters always wins at least half of the seats, something like Droop or D'Hondt proportionality is necessary. This is because a majority group always has at least half of all HB quotas, but may have one less full Hare quota than half of the Hare quotas. The basic reasoning here is that even in the single-winner case, some PR methods meeting the Hare Quota criterion can allow a minority to win and a majority to get nothing i.e. because of higher utility. Also see Marylander's example of free riding with a Hare-based PR method denying the majority half the seats: https://forum.electionscience.org/t/different-reweighting-for-rrv-and-the-concept-of-vote-unitarity/201/92 BetterVotingAdvocacy (talk) 03:58, 20 April 2020 (UTC)