I may have posted something similar previously. The idea is to allow national level proportionality with district based PR-STV. However, it doesn't assume that a first preference vote is the same thing as a party vote.
The voter gets to specifically choose which party to transfer his vote to and when in the count. Also, if the voter's vote is used to elect a candidate, then only the surplus part of the vote can be transferred to the party. The assumption is that the country is split into multi-seat districts and PR-STV is used to fill the the seats. It doesn't require central counting of all the ballots. In principle, the districts could be have as few seats as desired. Though, obviously, the more seats the better. Very small districts would hurt independents, but shouldn't have much of a negative effect on small parties, as they can recover proportionality at the national level. 4-5 seats would probably be enough to give a reasonable result. The same quota is used nationwide. This means that some seats won't be filled. Fair Majority Voting is then used to decide which party gets which non-filled seat to restore national proportionality. Each party's vote total is used to decide where they are stronger for that purpose. If there were no members of a party standing locally, the voter could give the party their first choice. Ballots contain a list of all the local candidates in the district and also all national parties. When voting the voter ranks the parties and candidates. A voter might vote Candidates A1: A2: 1 B1: C1: 2 C2: 3 D1: E1: Parties A: 5 B: C: 4 D: E: Note: ranking 2 parties is normally a waste of time The count process works as follows: Step 1: Count all the valid ballots Each district announces how many valid votes were cast The central office then calculates the total valid poll The quota is determined as the Droop quota but at the national level Q = floor [ (sum of all the votes)/(legislature size + 1) ] + 1 Note: This effectively gives a quota that is nearly equal to the Hare quota in each district. (It might be better to just use the Hare quota directly, and accept a slight inaccuracy, in the interests of the local count being localised) Step 2: Filling local seats This uses a PR-STV method. The only exceptions are - the national quota is used - the parties count as uneliminatable/unelectable candidates - candidates must reach the quota to be elected. Each district announces who has won seats and how many are left unfilled. It also announces how many votes were received for each national party. Note: Party vote totals don't include votes for candidates who are elected, it is just votes transferred to the party. They are the votes that correspond to the unfilled seats. Step 3: Sharing the remaining seats Based on the each party's vote sum, the unfilled seats are shared at the national level using d'Hondt or Websters. (It might be worth having a rule that if a party gets no seats (or fails to hit a threshold), then the districts are asked to transfer any votes for that party to the next choice, and the seats are distributed again.) (Also, it might be worth recalculating the quota and allowing one final transfer to the national party totals) Fair Majority Voting is used to decide how many seats each party gets in each district. Basically, each party gets a multiplier, and its vote total in every district is multiplied by that amount. In each district, the unfilled seats are split between the parties using d'Hondt and their modified party vote total. There is always a unique set of multipliers that give the correct national vote share (or at least I think this conditions in the Fair Majority Voting paper are still present for that to work). This is calculated by the central office and the result can be easily verified by looking at the district announcements. Step 4: Select candidates to fill the remaining seats In each district the votes that went to each party are used to fill the party's seats in that district. If the party gets 1 seat, a condorcet method is used. Otherwise, PR-STV is used. Only party members are eligible to be elected to party seats. ---- Election-Methods mailing list - see http://electorama.com/em for list info