Accuracy and Goals for Proportional Representation and Multi Winner Elections.
Multi-Winner Elections are a way to elect a council or team from a group of Candidates. If each seat was elected one-by-one the majority would always win and the council wouldn't do a good job of representing the diverse electorate.
Proportional Representation (PR) was envisioned as an ideal that the governing body should match the demographics of the electorate as closely as possible. There are a lot of proportional representation based voting systems that have been and are used around the world but there doesn't seem to be a lot of science around how to look at which system is best and how to measure if a given election is accurate.
We here at RCV Oregon are committed to working for accurate election reforms that better represent the people. A lot of us are here to solve the spoiler effect and allow honest voting. We've agreed on the 6 criteria: Honesty, Equality, Accuracy, Simplicity, Expressiveness, and Viability but for PR systems there hasn't been any clarity around Accuracy in particular. Who should win?
If we are looking at a 1-Person-1-Vote system then it's pretty simple to say that for example if there are 4 seats you need a 1/4 of the votes to get a seat. If the numbers don't work out that perfectly we can choose to round up and down so the needed threshold would be half way between: 13-37%=1 seat. 38-62%=2 seats. 63-87%=3seats. 88+%=4seats. The other way to do it is to say that you need the full 25% to get one seat. (I think VSE would prefer the former.) It's critical to decide what a needed quota is to be able to win each seat so that when we are actually looking at elections we can tell if a candidate won fair and square or if they are a non-representative winner who shouldn't have won.
Once we've decided what is a fair quota for a 1-Person-1-Vote system we can use that same quota for more expressive ranked and score ballot systems.
Currently we have been looking at Ranked Systems like IRV-PR aka STV, Re-weighted Range Voting, SRV-PR, and also more conventional district based Multi-Winner systems or some combination of PR and district based elections.
Note: I edited the word "spoiler" to other vocab that means basically when the wrong winner wins. Apparently a "spoiler" is specifically just vote splitting.