lpetrich
Contributor
There are several kinds of proportional representation.
Single transferable vote: a multiseat extension of instant runoff voting, with not only losers, but also winners, dropping out. To make the election proportional, each winner's ballots are either downweighted or else some of them are removed from the count.
That downweighting/removal step avoids a partisan election degenerating into general ticket: voting for slates of candidates in single-winner fashion.
That's a problem with bloc voting: voting for as many candidates as seats. With a partisan vote, it degenerates into general ticket.
This one requires relatively small districts, like 3 to 5 seats.
Proportional approval voting: vote for as many as one likes, and with each round of counting for finding a winner, downweight all ballots that elected winners. One can also do that with range/rated/score voting.
Party list: vote for a party, and each party gets seats in proportion to how many votes it got. There are various algorithms for doing this allocation.
Parallel voting: the chamber is split into two: a single-member-district part, the district seats, and a proportioanal part, the list seats, and one votes for a district candidate and a party. Only the list seats are made proportional.
Mixed-member voting: like parallel voting, but the list seats are populated to make all the seats proportional.
Single transferable vote: a multiseat extension of instant runoff voting, with not only losers, but also winners, dropping out. To make the election proportional, each winner's ballots are either downweighted or else some of them are removed from the count.
That downweighting/removal step avoids a partisan election degenerating into general ticket: voting for slates of candidates in single-winner fashion.
That's a problem with bloc voting: voting for as many candidates as seats. With a partisan vote, it degenerates into general ticket.
This one requires relatively small districts, like 3 to 5 seats.
Proportional approval voting: vote for as many as one likes, and with each round of counting for finding a winner, downweight all ballots that elected winners. One can also do that with range/rated/score voting.
Party list: vote for a party, and each party gets seats in proportion to how many votes it got. There are various algorithms for doing this allocation.
Parallel voting: the chamber is split into two: a single-member-district part, the district seats, and a proportioanal part, the list seats, and one votes for a district candidate and a party. Only the list seats are made proportional.
Mixed-member voting: like parallel voting, but the list seats are populated to make all the seats proportional.