[EM] Lock-in / robust two vote MMP

[Closed Limelike Curves]

>
> That could be extra helpful in South Korea, where the courts struck down
> the old mixed single vote system.

Oh god no what did I do

On Sat, Nov 30, 2024 at 8:21 PM Closed Limelike Curves <
closed.limelike.curves at gmail.com> wrote:

> 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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>
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