I haven't been following the discussions about using STAR Voting with multi-seat elections and so I don't know what has been proposed already. But I have been thinking about it and wanted to run what came to in mind by others.
Each voter scores each candidate as in single-seat election. Then the tabulations goes like this:
1. Top two runoff, one with higher score on more ballots wins (as in single-seat election).
2. Top two runoff of remaining candidates, including the loser of the first round, again one with higher score on more ballots wins.
3. Top two runoff of remaining candidates.. etc., until the seats are filled.
Is this anything like what has been discussed already? If not, is there anything wrong with it?
A non-proportional multi-winner election that it held at large is basically what we have in Portland and that many people are trying to repeal. Each seat is still won by the majority faction of the population and it does away with the natural proportional representation of single winner districts.
Single winner districts ensure that each area is proportionally represented according to it's population. This also means that each locality has a rep that they can hold specifically accountable if their needs aren't being met.
For this reason single winner STAR Voting would be MUCH better proportional representation than simple multi-winner. (Even with a STAR Ballot!)
The only problem with this approach is that it isn’t proportional— the majority will win all of the seats. Http://Equal.Vote/pr is basically what you are suggesting except that after each seat is elected it reweights all the ballots based on how much that ballot has “won” so far.
A current suggestion from another thread is this:
Multi-Winner STAR-PR: Voters fill out a regular STAR Ballot. All but the final seat are filled a la reweighted range voting (RRV.) The final round to fill the final seat is the only one that adds in a runoff. In the last round the top 2 are determined by RRV and then the finalist that was preferred by more voters wins that last seat.
Why do we only want a runoff in the final round? This maintains the runoff from STAR along with it's added incentive to honestly and expressively score each candidate. We only really need one runoff to get this benefit and it only really has a large impact on the final round. If you were a finalist in the 1st round who lost the runoff, odds are very high you will win the next round. The final round ensures that a finalist who is preferred by more voters wins. Cutting all the other runoffs makes for a much simpler system overall. Is this proposal still too complex? Maybe, but it's a simpler algorithm than STV!
I see the problem now. I'll have to check up on how the re-weighting works.