Score cascading vote: Difference between revisions

Unlike other proportional cardinal voting methods like [[Allocated Score]] and [[Sequentially Spent Score]], SCV ensures that voters have no risk of going into a candidate’s quota in a way that prevents them from filling the quota of a candidate they like more. The major strategic considerations under SCV are to:

SCV was inspired by the observation that the STV algorithm still yields proportional representation no matter what algorithm is used to determine which candidates to eliminate. Score has the advantage of simplicity; another approach would have been to use a ranked ballot and to use some [[Condorcet method]] to determine eliminations.

There are several motivations behind the choice to use the same scores throughout tabulation instead only the scores on ballots that have not already spent their votes. First, it is simpler not to have to recalculate the scores every time a candidate is elected. Second, using the scores on all the ballots is fairer; it means that a voter whose vote goes toward the first winner has as much influence over which candidates get eliminated as a voter whose vote ends up going to the final winner. This fairness also removes a major incentive for free- riding. However, using the same scores throughout tabulation necessitates the use of the Droop quota instead of the Hare quota; under the Hare quota, a faction that comprised a majority of the elected and had N quotas worth of supporters, plus one additional voter, could ensure that it won N + 1 seats.

[[STAR voting|STAR]] can be used instead of [[Score voting|Score]] for eliminating candidates and for selecting which of the candidates who reach the quota gets elected. That is to say, whichever of the two lowest-scoring candidates is preferred over the other on fewer ballots gets electedeliminated, and, when multiple candidates reach the quota in a round, whichever of the two top-scoring of these candidates compete in an automatic runoff and whichever is preferred over the other on more ballots is elected. This variant helps incentive voters to give some candidates one star instead of exaggerating those scores down to zero.