Final Review - Multiple Winner Elections Overview
This site has covered three distinct alternatives voting methods for a multi-winner race: Cumulative Voting, Single Transferable Vote, and Approval Voting. This section provide a quick review of the methodology of each system.
Cumulative voting is a method in which voters have one vote they can spread however they want among candidates. In the case of discrete cumulative voting, voters have a predetermined number of votes they may spread out however they want. For example, if there are five candidates to vote for, then a voter would only be able to vote using 1/5 fractions. This method allows people to express themselves more than any other voting method, but comes at the price of allowing people to vote strategically. It is also very complex as some voters may not know what fraction most accurately represents their preferences. And lastly, it can create inequity as some voters may not know how to work with fractions.
Single Transferable Voting is a ranked choice voting method that aims to achieve proportional representation in multi-seat elections.
The quota is calculated using the following equation:
2. Any candidate that meets the quota is automatically elected to a seat.
3. If the candidate’s total number of received votes is greater than the quota, the surplus votes are transferred to the next ranking candidate on the ballot using the formula:
4. Repeat steps 2-3 until all seats are filled.
5. If no candidate meets the quota, eliminate the candidate with the least number of votes. The rankings below them are shifted up, like in the Hare instant runoff method.
6. Repeat steps 2-5 until N candidates are elected.
Approval voting is a voting method traditionally used in single-winner elections. This voting method allows voters to vote for any number of candidates, and the candidates with the most votes wins the election.
However, in multiple-winner elections, approval voting is used to elect multiple winners of the candidates who received the most votes.
For example, there are four candidates, A, B, C, & D, and two possible winners. Candidates B & D receive the most votes, so both of them win and are elected.