Wednesday, December 27, 2017

Ranked-Choice Voting with a Supermajority Requirement

Some elections require a supermajority to cause an action to happen. A supermajority means more than a majority, and the most common supermajority requirements are 2/3 or 3/4 of the voters.

In this post we explain how you can implement a supermajority requirement for your online elections with OpaVote.

Why a Supermajority?

Most elections require a majority to enact a change because it allows you to make progress and move forward with a decision. If supermajorities were always required, then you could be stuck with the status quo and be unable to move forward.

Supermajorities are usually required for decisions of a more serious nature, such as removing a person from an office. For some decisions, it makes sense to stick with the status quo or not make a decision unless there is a supermajority who agree.

Supermajority Requirements with more than Two Candidates

Although supermajorities are somewhat rarely used, they are even more rarely used when there are more than two candidates or options to be considered. One example that I have seen is when a group is considering whether to endorse one of multiple candidates running for an office. The group wants to endorse one candidate, but only wants to do the endorsement if a supermajority of members agree. Otherwise no endorsement is made.

When there are more than two candidates, then you need ranked-choice voting (RCV). In this situation, you need to be careful to instruct the voters how to cast their votes. Voters must:

  1. rank the candidates in order in preference, and
  2. only rank candidates who they want the organization to endorse and not rank candidates who they don't want endorsed.

This is different from a typical RCV election where voters should be instructed to rank all candidates because later choices cannot hurt earlier choices.

 An RCV election typically ends when there are two candidates remaining, and the candidate with the most votes is declared the winner. For example, Alice may beat Bob with 55% of the votes. But how do we determine whether Alice is supported by a supermajority of voters for the endorsement?

The easiest way to do this is to recount the same votes with Approval Voting (and OpaVote lets you do this recount for free). If Alice has received approvals from a supermajority of voters, then Alice has been ranked on a supermajority of ballots, and she should receive the organization's endorsement.

If Alice wasn't ranked on a supermajority of ballots, then the organization could decide not to endorse any candidate or could decide to hold a second election to decide whether to endorse Alice and require a supermajority for the second election.