The spoiler effect

We see this every four years or so. A major party angers a group of voters by taking them for granted, then acts outraged when said voters form a third party. We then get the whining about the "spoiler effect," claiming the effort will elect the worst of all evils.

One possible solution to the problem is instant-runoff voting, which would eliminate the spoiler effect, by giving voters the option of a second choice should their candidate not get enough votes to be viable.

This would, of course, end the two-party system, allowing multitudes of parties to flourish, which is why it will never pass.

Julie J. Rehmeyer, writing for Science News Online takes a look at various voting systems. Our current system, in which the candidate who gets the most votes, regardless of a majority wins, is known as the plurality system.

Mathematician Donald Saari tells Rehmeyer "The plurality vote is pretty much the worst voting system there is."

As Rehmeyer's article shows, even if IRV passed, how to count the votes poses all sorts of questions:

Though this example is especially dramatic, Saari has found that determining voters' preferences from their ballots is often tricky. For example, suppose three candidates, A, B, and C, are competing. The preferences of the voters are as follows:

• 3 people rank A first, B second, and C third;
• 2 people rank A first, C second, and B third;
• 2 people rank B first, C second, and A third; and
• 4 people rank C first, B second, and A third.

Plurality voting would name A the winner, with 5 votes.

On the other hand, suppose one wanted the candidate that was least disliked. Six people rank A last, two people rank B last, and three people rank C last, so in that case, B should win.

Yet another method would be to assign 2 points for a first place vote, 1 point for second place and none for third. In this method, known as the Borda count, C walks away the winner with 12 points, beating out B's 11 points and A's 10.