I had missed most of the following discussion earlier, and as it occurred in a thread on Lower Saxony, it could easily have been missed by others as well.
I am going to reproduce two comments that describe interesting ideas for coping with thresholds.
Vasi:
there’s no reason you couldn’t make thresholds less discontinuous, by combining them with preferential votes.
The mechanics would be a tweaked STV, with the following differences:
1. Because of large district magnitude, a full preferential vote for all candidates would be impractical. Instead voters would list parties in order of preference, with the intraparty order being fixed as in List-PR.
2. To effect a threshold of T seats, a party would not be awarded its first seat until it has accumulated T quotas.
Chris:
Vasi, that sounds essentially like the NSW Legislative Council electoral system.
The election is by STV, with 21 vacancies at an election. One has the option of either voting below the line, by ranking at least 15 candidates, or voting above the line, by voting for one or more party tickets. Unlike federal Senate elections, voting for a party’s ticket does not result in a vote for a preset preference ranking of every candidate; instead, it only ranks the candidates of that party, in the order they appear on the ballot paper. Voters have the option of marking multiple parties above the line, unlike federal Senate elections. So, for instance, the Labor how-to-vote cards in the last election suggested that their supporters vote 1 Labor, 2 Greens above the line. That means they essentially ranked every Labor candidate, followed by every Greens candidate, and if all of them are elected or excluded, their ballot is exhausted.
The Australian group voting ticket essentially operates like closed-list PR, with the exception of in very large elections. The NSW Legislative Council used to use the same ticket style system that the federal Senate uses, but after the 1999 election resulted in a ballot paper the size of a tablecloth (almost 1 sq. m), and a candidate from the “Outdoor Recreation Party” got elected with 8,000 first preference votes (something like 5% of a quota), they changed the group-ticket system to the single party ticket system now in place.
Stephane Dion, the former Leader of the Official Opposition in Canada, also is advocating a version of party-preferential voting. though in ridings which would be only 3-5 seats (1 seat by AV in the territories). In a 4-seat riding, the threshold would be 25% + 1 vote. If all remaining parties are above the threshold, seats are awarded to them by largest remainder (I believe). If there are any parties remaining below the threshold, the party with the least votes is eliminated and their supporters votes transferred to their highest remaining preference. His system is OLPR, with each voter able to cast a preference vote for one candidate of his first-preference party.
I think the most proportional system possible would be party-preferential with a low threshold and a large district magnitude (the most proportional would obviously be a single national district). You could either exclude parties one-by-one (hopefully with block exclusions) until every party remaining was above the threshold, then distribute seats. Otherwise you could simply exclude all parties below the threshold and distribute their voters’ preferences to remaining parties. It avoids the huge numbers of voters wasting their votes by being below the thresold; for instance, even with a relatively low threshold of 3%, 19% of the valid votes in the May 2012 Greek election were cast for parties below the threshold. In this system, the only voters who do not have either a first preference or a transfer vote elect an MP are those who deliberately choose not to rank any parties that make it into parliament.
I also think a novel way to build a stronger government while remaining representative of votes would be to use preferential ballots, but with multiple thresholds. In a 120 seat legislature, 60 seats could be awarded to those parties above 2%, with voters below the threshold transferring to their highest placed remaining party. Then a further 30 seats could be given to those parties above 5% (including transferred votes), then a further 20 seats to those parties above 10%, and then the final 10 seats to the party which wins a majority by transfers. This means that even voters who vote below the threshold are represented, and parties with a decent amount of support have representatives in parliament, just not proportionally to their first-preference votes. You also get larger parties at the top, making a stable government more likely, but unlike supplemental member, or the Italian/Greek plurality-winner top up system, the larger bloc is distributed based on all voters’ preferences, retaining a much larger degree of proportionality than other semi-proportional systems.
I am not necessarily endorsing this concept, although I do find it very interesting. I would be interested in further discussion.
The thread has a lot of other interesting comments on the relationship of thresholds to democratic theory (particularly the last several comments posted as of 4 February). I re-posted the two comments above simply because they refer to proposals for an alternative way of coping with thresholds in electoral-system design.
(I did note the Dion proposal before.)