Ranked Ballots for Canada

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Ranked Ballots Avoid the Vote Splitting Strategy

One of the ways in which plurality voting (sometimes called first-past-the-post) can fail to capture the preferences of voters is through “vote splitting.” Vote splitting means that two candidates who are liked equally by a majority of voters, or where voters like both better than the other candidates are less likely to be elected than a candidate who is disliked by the majority.

Vote splitting is possible for any election or referendum that has more than two options and where the one that has most votes wins. For example, in 1969 when the Ontario towns of Fort William and Port Arthur chose to amalgamate, residents were asked to vote for one of three new names: “Lakehead,” “The Lakehead,” or “Thunder Bay.” The name “Thunder Bay” won by a 568 vote margin with 15,870 votes, “Lakehead” got 15,302, and “The Lakehead” got 8,377. The winning name had 40% of the votes because the other two candidates were so similar.

Suppose you are one of three candidates in an election. Polls say that 36% of voters intend to vote for you, while 38% intend to vote for candidate A and 26% intend to vote for candidate B. Rather than convincing other voters to support you, you focus on convincing some supporters of candidate A to vote for candidate B who has a similar platform. If just 3% of voters decide to vote for candidate B rather than candidate A, you will win by 36% to 35% to 29%, without needing to convince any more people to vote for you. Vote splitting is a simple low-cost electoral strategy, but it means the result may not be the preferred choice of most voters.

The strategy is legal, but in 1995, an illegal version of the scheme was used in Manitoba, where a political party financed independent candidates to split the vote of candidates of another party.

Many electoral systems are susceptible to some form of vote splitting, including plurality voting like the one used in Canada, Mixed Member Proportional (MMP), and any proportional system with a minimum threshold.

Run-off voting with two or more rounds or voting, and ranked ballots (sometimes called instant run-off) solve the problem of vote splitting. With ranked ballots, you mark your first, second, and third choice. If your first choice comes in last, and no other candidate is the first choice of more than half the voters, then your second choice ballot is used, ensuring that the winner has the majority either of first-choice ballots, or failing that of first and second choice ballots and so on.

When ranked ballots are used, it is not possible to win with vote-splitting, whether the vote splitting occurred naturally or was a deliberate strategy, or an illegal scheme. The only way to win is to be chosen by an absolute majority of at least 50% of voters.

2 comments for “Ranked Ballots Avoid the Vote Splitting Strategy

  1. gragor
    June 2, 2015 at 4:21 pm

    Now who are these guys and why are they advertising in that right hand Book of Faces column? Pause to ponder as we are going to have to change our voting system from First Past the Post but what are these guys up to and who is bank rolling them?

    • tonobungay
      June 17, 2015 at 11:37 pm

      Gragor, it’s individuals like you, not an organization. Join us if you like! The “bankrolling” is small contributions from individuals. We’ve spent $50 on advertising so far, contributions are welcome!

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