[EM] Lock-in / robust two vote MMP

[Abel Stan]

Yes, I would think that is possible, that's partially what I was implying
when I said it could work with approval systems too.
Can you refer me to the South Korea court decision on that? Is it
specifically the mixed single vote that was the problem?

I also think even without flexible leveling seats and a small number of
list seats it would be an improvement over current two-vote "MMP" systems
like in South Korea (but also NZ, Scotland, etc.). And again, in my
opinion, the traditional way of measuring proportionality based on "second
votes" (list votes) would not do it justice, since it would be more
proportional than that if you consider sincere split ticket voting.
However, in any case, the vulnerabilities of one vote seats linkage ("MMP")
still apply.

I would also point you towards Jameson Quinn's "modified Bavarian MMP" (on
electowiki) which uses the same principle but the vote linkage works in two
ways, also more sophisticated than my basic solution as it adds an extra
chance of the ballot not being lost if not only does the voter not support
the SMD winner, but the party vote is for a list under the threshold.


Closed Limelike Curves <closed.limelike.curves at gmail.com> ezt írta
(időpont: 2024. dec. 1., V, 5:21):

> Thinking about this: paired with proportional approval voting, this could
> be a very good way to create a "second tier" while keeping the overall
> system simple and easy to understand. That could be extra helpful in South
> Korea, where the courts struck down the old mixed single vote system.
>
> Rules: every voter has 1 vote, which is equally divided between the
> winning candidates they approve of, plus the party they support. This way
> the party receives the "wasted portion" of every voter's ballot, i.e.
> 1/(n_approved_winners+1) votes.
>
> You should be able to get away with very few list seats, since the local
> elections are already mostly proportional. I'm mulling over how this
> compares to my current-preferred system (mixed single vote with
> Pukelsheim's method), especially strategically.
>
> (Am I right in guessing you're "Rankedchoicevoter" on Wikipedia, BTW?)
>
> On Mon, Aug 5, 2024 at 3:12 AM Abel Stan <stanabelhu at gmail.com> wrote:
>
>> Hello everyone,
>>
>> I am quite new here, and so far I am unsure whether a mixed method is
>> going to raise your interest, but I would be very happy if you'd give it a
>> chance. I had the idea about 2-3 years ago and have procrastinated on
>> trying to publish it as a paper in a journal, which I would now want to
>> really do, unless I find out that it is not new at all. I would also be
>> grateful for any advice on that too if anyone has experience. So far I have
>> encountered the idea only in traces, never fully described even though it's
>> very simple, it might be one of those simple ideas that you just don't
>> think of and once you hear it it doesn't seem new or you might assume
>> that's already how it (MMP) is.
>>
>> My preliminary names for it are: "lock-in" MMP or "robust (two vote)
>> MMP". It's not perfect, it shares all the flaws of single vote MMP in case
>> there are not enough leveling seats or no cap on constituency seats per
>> party.
>>
>> The problem is this (just saw this article explain it too:
>> http://rhysgoldstein.com/2018/02/03/bon-mmp-bad-mmp/):
>> One vote MMP is much more robust to strategic nomination (decoy lists)
>> than 2 vote MMP, and it doesn't have the ticket split strategy. But you
>> sacrifice the very important choice of sincerely splitting your vote (you
>> like your local candidate, but not their party and vice versa)
>> There is another system which solves this problem: the mixed ballot
>> transferable vote (MBTV), which uses vote linkage instead of seat linkage.
>> Vote linkage is less known and had some not so good implementations that
>> might give it a bad reputation. But theoretically, with (single vote) vote
>> linkage, you can eliminate strategies almost completely (I'd refer to
>> Daniel Boschler's work on this), unlike with single vote MMP (seat
>> linkage). You just need the correct formula (I would like to write a paper
>> on this too, but it's less impressive since it's very impractical). The
>> problem with even the "perfect" vote linkage system is that you need a lot
>> of additional list seats, possibly even more than 80% of seats would be
>> list seats, and you need an assembly that changes size every election. But
>> with the mixed ballot transferable vote, you at least can have two votes
>> without major issues.
>>
>> Ideally, we want a two vote version of seat linkage (which is way more
>> efficient) which doesn't suffer from the problems of two-vote MMP. So a one
>> vote MMP, but with actually two votes! Here's the solution:
>> You need a mixed ballot, like in the German elections, so the two votes
>> have to be in the same ballot. You read the ballot preferentially (like in
>> STV or MBTV), but like this: If someone casts a ballot for the plurality
>> winner their ballot gets "locked-in" for that party list. You cannot split
>> your ticket then, your vote is already counted to elect someone, you don't
>> get to vote for another party and get them list seats (whether sincerely or
>> not). But, if you didn't vote for the plurality winner, your vote doesn't
>> get locked in, your ballot counts to your list vote. The total used for
>> top-up is the sum of the locked-in votes and the non-locked-in votes. The
>> closest thing I found to this is that in Germany, if you voted for an
>> independent who got elected, your second vote didn't count - which is good,
>> otherwise it would make sense for every party to run "independents" who
>> don't count for their list with compensation. Also, some papers on mixed
>> systems theorised there is something that uses both seat linkage and vote
>> linkage, but not like this: They mean the MMP variants where the two votes
>> are added together, a crude but partially effective solution I assume.
>>
>> There are a few things to figure out: How to measure proportionality?
>> With one vote and two vote MMP it's clear, you can measure how well you
>> compensated to the list results, with lock-in MMP there is an intermediate
>> "fictional" list vote total used for top-up, so I think this is the real
>> yardstick of proportionality. Compensating towards the pure party list
>> result actually hides that some can have more voting power than others.
>> Another thing is independents if the ratio of SMD to list seats is 50:50,
>> then any plurality winner under 50% is already lucky to get their seat,
>> those votes don't lock into a party list (they lock into "none"), since
>> independents have none. So like in one-vote MMP, independents can actually
>> be a flaw in the system. But if independents receive more than 50% of votes
>> (assuming equal population and turnout across districts), maybe those
>> surplus votes should be "freed" like in STV. Many other things can be
>> considered, like using it with ranked or approval systems, but this is just
>> the main idea.
>>
>> Thank you for reading and I appreciate any feedback, especially if you
>> know that this is not actually a new idea or that it has a fatal flaw
>> (other than what the default one vote MMP already has).
>>
>> Best,
>> Abel
>>
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