[EM] LAP representation (district-based PR)

[Jameson Quinn]

Here's the link for my newly-proposed PR system "LAP (Locally-Accountable
Proportional) representation<http://wiki.electorama.com/wiki/LAP_representation#Advantages>".
Comments and suggestions on rules or naming are welcome.

Here's a copy of the page:

LAP representation

LAP (Locally-Accountable Proportional) representation is a system for
electing a legislature, such that ballot secrecy is preserved but each voter
can know who their representative is. Unlike with single-member districts
(as currently used in the US and UK), an overwhelming majority (not just a
little more than half) of voters will have a representative whom they've
actually supported in some way. It is designed to be a gentle change from a
single-member-district system, and districts can remain unchanged. Most
representatives will represent multiple districts, and each district will
have one representative from each represented party. For instance, if two
parties divide the legislature 50:50, then each representative will have two
districts and each district will have two representatives (one from each
party). The basic idea is:

   - Candidates pre-announce their rank-ordering of the parties (starting
   with their own party) and may optionally approve/disapprove within each
   party candidates. Their votes will never be transferred to disapproved
   candidates.
   - Voters may vote on the candidates in their or nearby districts, or
   write in candidates from farther off. Votes are delegated by default but
   optionally, voters may refuse to delegate or vote approval-style.
   - Each delegated ballot is transformed into the pre-announced vote of the
   candidate it supports.
   - A legislature is elected by a version of
STV<http://wiki.electorama.com/wiki/STV> (with
   fractional transfers and a Droop quota.)
   - Each district "drafts" one member of each elected party from the
   elected slate.
   - Your representative is the member of the party you voted for who is
   representing your district.

[edit<http://wiki.electorama.com/wiki/index.php?title=LAP_representation&action=edit&section=1>
]Full Procedure

   - Candidates pre-announce their rank-ordering of the parties (starting
   with their own party) and may optionally disapprove of any other candidates.
   - Voters may vote on the candidates in their or nearby districts, or
   write in candidates from farther off.

First, to simplify the ballots, the population is separated into a
"district" for each seat, and "districts" are grouped into sets of 2 or 3
"co-districts". The ballot for each district lists the incumbents and
candidates from that district in a larger font, and the candidates from its
co-districts below that in a smaller font. Write-ins may be used to vote for
candidates from other districts not listed on the ballot, so the districts
only matter for ballot simplicity (Voters do not want to have a ballot with
many dozens of candidates on it, but write-ins allow full freedom for those
voters who want it). Larger parties will usually run one candidate per
district; smaller parties may just run one candidate per co-district set.

   - Each vote is transformed into the pre-announced party preference order
   and individual approvals/disapprovals of the candidate it chooses.
   - A legislature is elected by a version of
STV<http://wiki.electorama.com/wiki/STV>
   .


   - Delegated votes first count full-weight for their chosen candidate.
   Once that candidate is elected or eliminated, a vote is divided equally
   among all non-disapproved, non-eliminated members of the top party remaining
   on that ballot with any such members.
   - Undelegated votes are divided equally among all approved,
   non-eliminated candidates on that ballot.
   - Any candidates who reach a Droop
quota<http://wiki.electorama.com/wiki/index.php?title=Droop_quota&action=edit&redlink=1>
are
   immediately and simultaneously elected, and their ballots are reweighted to
   eliminate a Droop quota.
   - If there are no candidates who reach a Droop
quota<http://wiki.electorama.com/wiki/index.php?title=Droop_quota&action=edit&redlink=1>,
   the party with the fewest votes is identified, and the candidate from that
   party with the fewest votes is eliminated. All votes for that candidate are
   reassigned as outlined above.
   - If the above finishes without electing a full slate, the last candidate
   to be eliminated is elected.
   - If there is still no full slate, the process is rerun from the
   beginning (again electing the last candidate standing) until a full slate is
   reached.


   - Each district "drafts" one member of each elected party from the
   elected slate.

The draft proceeds as follows:

   - First, each representative is drafted by their home district.
   - From then on, the draft proceeds in descending order of votes. That is,
   if more votes from district 1 go to candidate A than any other eligible
   district:candidate pair, then A is drafted to that district.


   - General rule: All representatives from a party must be drafted N times
   before any representative from that party may be drafted N+1 times.
   - General rule: No district may draft two representatives from the same
   party.


   - Your representative is the member of the party you voted for who is
   representing your district. If no member of the party you voted for was
   elected, then you may look at the public ballot of your chosen candidate to
   see which of your district's representatives is yours.

[edit<http://wiki.electorama.com/wiki/index.php?title=LAP_representation&action=edit&section=2>
]Advantages

   - If:


   - all votes are for one of the two main-party candidates in the voter's
   district,
   - all candidates approve everyone from their party
   - and the districts are divided fairly so that plurality would give a
   proportional result

... then LAP representation (like SODA-PR or Balinski's "Fair
Representation") gives the same results as plurality. These assumptions will
not generally be perfectly true, but they will generally be close to true,
so LAP representation will give results that are recognizably similar to
those of single-member districts. It is hoped that this would make it a more
acceptable system to politicians who have won under single-winner rules. [
edit<http://wiki.electorama.com/wiki/index.php?title=LAP_representation&action=edit&section=3>
]Justification

A modified version of STV is used as the proportional system for simplicity.
Other proportional systems (such as BTV [Bucklin Transferrable Vote]) would
also work. The equal ranking, and resulting fractional division of votes, is
necessary for three reasons. First, it allows for approval-style votes to be
counted without complicating the ballot. Second, it allows candidates to
exercise judgment independently from their party (disapproving of certain
party members), but keeps the voter's judgment as primary. If candidates
couldn't exercise judgment, parties would have to waste energy keeping out
"crazy" candidates who affiliate only because of the transfer votes they
might get. If candidates could fully-rank within the party, as would happen
if the PR system were standard STV, there would be too many opportunities
for logrolling, at a level of detail where voters wouldn't realistically
keep track or hold candidates accountable. Third, equal-ranking allows us to
claim that this system could, under reasonable circumstances, elect exactly
the same representatives as a non-gerrymandered single-member-district
system.
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