Tuesday, November 3, 2009

Spoiler Alert

On this election day, many New Jersey voters faced a common, unsatisfying, and ultimately unnecessary choice: vote for the best candidate, or vote for a candidate that the polls suggest could win?

Why unnecessary? In a reasonable electoral system, voting for the person you prefer would not increase the chances for someone you don't. But that's not how we do it.

A typical vote today awards the election to the candidate with the most votes--a plurality, not necessarily a majority. If a third candidate enters a two-person race, he or she is more likely to draw votes from the more similar candidate. The result is that an extra candidate with a particular viewpoint can reduce the chances of that viewpoint prevailing. This is the "spoiler effect."

The best known example is Ralph Nader's entry in the 2000 election in Florida. Although Nader got only a few percent of the votes, if everyone who voted for him had voted for Gore, Gore would have beaten Bush--in Florida, and in the country.

But there's nothing liberal or conservative about the problem. Any candidate can lose because of a strong third-party candidate with similar views.

This is just wrong.

It should be changed.

And there is a simple way to change it.

In instant runoff voting, voters rank all the candidates, rather than just voting for their first choice. Not too hard, right?

If no one gets a majority of first-choice votes, the candidate with the fewest is eliminated. Those ballots are redistributed to the second choice on each ballot. No votes are "wasted," but voters get to express their true preference.

The results are exactly to what would happen in an ideal runoff election, except that there's no need for the expense and low turnout of a second election.

In 2000 Florida, for example, Nader would have been eliminated, and the ballots that listed him as first choice would have been allocated between Bush and Gore, depending on who people listed as their second choice. In 2009 New Jersey, independent Chris Daggett was expected to draw more votes from the Republican candidate, which could tip the balance to the Democrat.

Many individual cities, like Oakland and Memphis as well as some national elections use instant runoff voting now. There's nothing particularly difficult about it, except that the two dominant parties may see it as a threat to their exclusive right to power.

Instant runoff voting isn't perfect. Pretty much all voting systems have some quirks that sometimes give results that seem obviously wrong.

But it's not nearly as bad as what we have now.




  1. It's a fallacy to think that IRV is supportable just because it's "better than what we have now".

    First of all, how much better? Bayesian regret calculations by a Princeton math Ph.D. named Warren Smith (featured in the William Poundstone book _Gaming the Vote_) show that IRV is not hugely better than plurality voting -- especially with lots of strategic voters, like the ones using the How-to-Vote cards in Australia's IRV elections.

    Now factor in some of IRV's _problems_

    1) More fraud-prone because it cannot be sub-totaled in precincts like plurality/score/approval voting and others can be.

    2) Typically increases ballot spoilage by about a factor of 7.

    3) More conducive to the implementation of fraud-prone electronic voting machines.

    4) More expensive than plurality voting for a multitude of reasons. (Claims that it is "cheaper" are falsely comparing it to plurality voting with runoff elections, and eliminating runoff elections does save money, but that has nothing to do with IRV.)

    So at best IRV is a very small improvement. But how could one argue against even a small improvment? Isn't that still an improvement? Well, not exactly.

    See, there's an economic concept called "opportunity cost". Say you have some money and you spend it on something that benefits you. That may be a benefit, but say you could have spent it on something that would have benefited you TWICE as much. Then by acting as you did, you actually HURT yourself, relative to how well off you COULD have been.

    The same is true in voting reform. Reformers are a limited resource. It's hard to get the money and volunteer time to change the system. It's hard to get initiatives on the ballot. If we spend that limited reform energy on implementing IRV, when we could have got something vastly better like score voting, then we've effectively harmed ourselves.

    This point is usually missed because it's not so obvious.

    In any case, here's an open question for IRV proponents:

  2. Thanks for your comments and links, brokenladder.

    There are certainly some important issues in comparing various non-plurality voting schemes. For me, I've had to make the desirability/electability trade-off enough times that I regard a rather easily understood method to avoid that as a highly worthwhile goal. I don't want the perfect to be the enemy of the good. At this point we're pretty far from getting widespread adoption of any alternative system.

    The first priority is for the public to recognize that the spoiler effect is not some civic failing of the third candidate but a structural failure of our voting system.