Raph Frank wrote:
That's fine. In fact, if you had 50% local and 50% national seats,
then it can be made to work perfectly.
Just say that an independent must get at least 50% of the constituency
to be elected and if he does, each of his voters have their weights
reduced to
(VA-50%)/100% where VA is his percentage vote share
This gives perfect proportionality.
In effect, it 'costs' 50% of a constituency to win a seat, and the
independent has managed it and so gets a seat. The candidate's
supporters 'spend' enough votes to elect the candidate and the rest go
to the national count.
IRV could even be used to make it a little fairer to possibly push a
candidate over the 50% mark. (Exhausted ballots wouldn't affect the
quota, so 50% would be a true majority). Any ballots which end up
with the independent would be de-weighted if he is elected. This
would mean that voters would be advised not to rank independents that
they don't actually want to get elected.
Or one could use STV instead, and have more local seats. If I'm not
wrong, the 50% mark of maximum disenfranchisement would be lowered
significantly by STV, so fewer list seats would be required.
If there were 50 top-up and 100 local, then the A party would get 100
and the B party would be assigned all of the top-up seats.
Ah, I see now. No amount of reweighting would handle that case for FPTP
because the 100 seats are already elected. As I said in the other post,
the logical thing to do at this point is to start deweighting
A-victories, although the A-voters would complain. In this two-party
case, this results in a problem, however, since exactly 51 out of 100
voted for A in every district. Thus, deweighting A would do nothing
until a certain point where A loses all its seats and B gains them. The
right thing would be that A retains some of the seats while B gets the
rest, violating the constituency preferences only enough to get
proportionality. But if all districts are equal in preferences (51 out
of 100 for A), then which should get their preferences overridden? That
would be done either randomly or by ignoring neutrality - for instance
by picking based on geographical properties so that the overridden
constituencies are as evenly distributed as possible.
Under some rules, the number of top-up seats can depend on the results
of the election.
One rule is that all parties must get at least 1 seat assigned. An
independent on 50% of a district wouldn't get assigned any seats until
the number of national and local seats was equal.
Another option would be saying that if any independent gets elected,
the number of top-up seats must be equal to the number local seats.
A less severe version would be to activate the rule if more than x%
(say 5%) of the legislature are independents. This would still cause
slight imbalances, but shouldn't be major. It would also prevent a
major party using the decoy list strategy as if they did, it would
trigger the rule and thus cancel out the effect, as there would be
enough seats to completely compensate.
In general, one should be careful with a variable size assembly, since
the size can go beyond all reason if the disproportionality is driven to
be severe enough.
Decoy lists don't have to be on independents, though. The strategy that
was used in Italy was that they had "constituency parties" and "list
parties". Voters would elect the constituency party for the constituency
and the list party for the top-up. Because there were no list proportion
for the constituency party, it could not be balanced in that direction,
nor could it be balanced in the list direction because nobody voted for
the list party in any constituency.
Schulze's STV-MMP method suggests that, in this case (party overhang),
some voters who voted for party A in the constituency and party B for
the lists, are set so that a fraction of their list votes go to A instead.
My issues is that there are 2 types of candidates
- party candidates
If a party candidate wins a seat, they get 100% of the representation
for that constituency. However, this is compensated by the fact that
they count as 1 seat won for the party.
This votes budget for that district is
Winner won a local seat
+ 1 local seat for the party
Winner counts as a party member
- 1 national seat for the party
All party votes added to party list totals as normal (1 person, 1 vote = fair)
By assigning the seat to the local winner, the winner's party loses a
seat at the national level, so it is neutral.
- independents
Winner won a seat
+1 seat for the independent
Candidate doesn't count as a member of any party
No effect on national vote
All party votes added to party list as normal (1 person, 1 vote)
Here, despite the winner winning a seat, all of his supporters still
get full effect at the national level.
Even if their votes were not eligible for the national count, it still
isn't fair as it hasn't cancelled a full seats worth of votes.
I see. I thought that the reweighting would act as a de facto -1
national seat. But if there are less national seats than there are
constituency seats, and the disproportionality can reach just below 50%
on a single constituency, then that doesn't work.
I guess I should be more precise. What I meant was that the voters do not
vote strictly according to any party's wishes on the constituency ballot.
They do, however, vote for various (different) parties on the list ballot.
If no candidate has a 2/3 majority in the constituency, that constituency
still has to elect a candidate. Okay, that's fair enough. But now you can't
use quota-based adjustment, since neither of the candidates met the quota,
so it seems your adjustment must be based on the votes cast, or on relative
support. In ordinary STV, you could just eliminate all the candidates, but
the district constraint prevents that.
If no independent meets the threshold, give it to the party based
candidate who gets the most votes. The only condition is that the
candidate's party must have enough spare national seats.
The process could be
Local count
1) Count all local votes
2) Assign each district to the, independent who exceeded the threshold
or party candidate, with the most votes
3) Reduce weight of ballots cast by voters for winning independents
4) Announce votes for each party (including any weighting) and votes
for each candidate
(constituencies are undefined if won by an independent who didn't hit quota)
National count
1) Work out how many seats each party is entitled to
2) Find candidate who stood in an undefined constituency, who has the
most votes and who's party is entitled to more seats.
3) Declare that candidate a winner and repeat until there are no such
candidates.
4) Declare any remaining undefined constituencies using some other
rule ... this shouldn't happen if all parties run candidates in every
constituency
5) Assign top-up seats in accordance with party lists so that each
party has the correct number of seats.
In that case, it doesn't matter which one of them wins the seat as
assigning them a seat is compensated by a seat at the national level,
so proportionality is maintained.
If we can replace FPTP by STV-PR (or another proportional multiwinner
method) so that the independent threshold is lowered, then we may be
onto something here. It's quite complex, though. Also, I think that the
national seats should be separate from the local seats, with the
candidates "representing the nation" as it were. If you really want to
complicate matters, you could have multiple top-up levels ("representing
the counties", "representing the state", "representing the national
area") to retain local proportionality as much as possible.
Anyway, I guess my concern is shown by the decoy list strategy.
Fundamentally, MMP allows an independent to get a seat while not
having enough votes to be entitled to that seat. This leads to
potential abuse or just unfairness.
Is that, in your opinion, a problem inherent to single-winner methods, or
just to MMP as it's usually employed?
That's a good point. Single seat methods all suffer from this problem
and it is even worse for them as they don't even attempt to
compensate. MMP brings the result closer to a PR result and my issue
is that it doesn't it all the way.
There is, of course, the observation that no method can have perfect
proportionality. Even party list PR would be subject to the quantization
given by the finite number of seats of the assembly. That aside, I get
what you're saying. What I'm trying to fix is the odd behavior of MMP
under strategy - its edge cases rather than its average case behavior.
Using STV-PR instead of FPTP would affect the average case behavior too,
obviously, but only in a good way, I think.
(Another observation is that edge cases are more serious than one might
at first think, at least as long as some participants have an incentive
to move the system towards those cases, because the system faces a
partly adversary input. In this manner, it's a bit like the difference
between ordinary bugs and security-related bugs in computing.)
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