[EM] Lock-in / robust two vote MMP

[Abel Stan]

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
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.electorama.com/pipermail/election-methods-electorama.com/attachments/20240805/32be4b39/attachment.htm>