What type of RCV works best and why?

Answer

Single-Winner vs. Multi-Winner RCV

Depending on the election, there are two types of ranked choice voting (RCV): single-winner and multi-winner. In an election for an executive office, such as mayor, governor or president , the single-winner version is often referred to as instant runoff voting (IRV).

 If three or more candidates were running for mayor, voters could rank the candidates in order of preference (1st, 2nd, 3rd, etc). Ballots are initially counted by tallying all 1st choice votes. If one candidate gets a majority of the 1st choice votes, greater than 50% then that candidate is elected.

If no candidate has a majority after the first count, the candidate with the lowest number of votes is eliminated. The voters who had that candidate as their 1st choice will then have their vote count for the candidate they marked as their 2nd choice. Elimination of last-place finishers and counting next choices on those ballots continues until one candidate gets a majority of votes in that round and is elected.