Tuesday, November 30, 2010

Voting for the Best Comments

Lots of websites have a comment section. Some sites which get huge numbers of comments have a sort of voting system for determining which comments are helpful, and which are not. The website of the San Francisco Chronicle is an example of such a site: this article on Oakland's use of ranked choice voting (AKA instant runoff voting) shows the system in action.

You'll note that, for each comment, you can give it a "thumbs-up" or a "thumbs-down", or leave it alone; the difference between ups and downs gives each comment a net score, and the most highly-scored comments get preferred listing. This is an example of range-3, i.e., range voting with three levels. Meanwhile, comment sections at The New York Times allow you to "recommend" comments, and the most-recommended comments get preferred listing. This is an example of approval voting, and is probably the most common sort of comment-voting setup on the internet.

However, I have never seen anywhere on the internet a comment-voting setup that used any sort of ranked-order voting system. (Although Kitten War comes close to a Condorcet system, sort of.) Why do you think that might be the case? Of course, who our next elected representatives will be is a much more important question than which is the most helpful blog comment (and obviously, when the stakes are so much higher, captchas and email-verification wouldn't be used for voter-roll identification) but the theory is the same: many people will have an opinion, and we want to aggregate those opinions to express a single, group opinion. If range and approval voting work so well in one domain, there's good reason to expect that it will work well in the other.

Thursday, November 11, 2010

A Third Party? We Already Have One (Or Thirty)

Since last Tuesday, there have been more than a few articles written clamoring that we need a third party to rescue this country from the terrible evils that the Republicans and Democrats are laying upon it. A third party, we're told, will really resonate with the voters; will unite them against the two "basically identical" major parties; will end corruption. There's only one problem: we already have a third party.

Actually, we have several "third" parties. The Libertarian party, if you add all the races together, got over one million votes for the House of Representatives this year. The Green party got more than twice that many for President just 12 years ago. And the Libertarian, Green, and Constitution parties have all run nation-wide Presidential tickets in every election since 1992. And that doesn't even count the literally dozens of smaller and regional parties.

Maybe you think there's a growing trend? That, yes, it's true that this has been going on for decades, but that's because it's building slowly, and now it's clear that the wave is about to crest, and a three-party utopia is on the horizon! Well... not so much. There have consistently been three or more new political parties founded in every decade of the nation's history since at least the 1840s, and some of them have done much better than any of the ones we have now. The only exception to this rule is the 1860s which, significantly, is the decade of the civil war and, related, the decade after the Republican party replaced the Whig party as one of America's two major-parties. (And by the way, the Republican party was never a third party.)

Third parties come, and third parties go; if they're lucky, they get to have some indirect influence on the debate by way of being a credible-enough spoiler threat. Occasionally (once a century or so) a major-party goes, and a new major-party forms to take its place—never (yet) an existing third-party. And that's the way it is, because third parties can't win this game.

Anyone who is whining that America needs a third party to "save" it then, is wrong for two reasons: we already have them, and they can't save us. We have a two-party political system because we have a two-party voting system, and if you don't like the former, you have to change the later.

Approval voting and score voting allow third parties a real chance to grow and actually win elections. That would, at the very least, facilitate a faster rate of change of who the two major parties are, and perhaps even lead to a long-term three (or more) party system. This would then speed the rate at which new issues, new ideas, and new ideals, are incorporated into our political discourse.

Consider that the Whig party collapsed because neither it nor the opposing Democratic party could discuss slavery, and that the Republican party's rise was because it could. Had this changeover not been artificially retarded by an inefficient voting system perhaps war could have been avoided. If war really is just the continuation of politics by other means, then a better voting system really is a matter of life and death. I ask you to give this a moments thought on this Veteran's Day.

Wednesday, November 10, 2010

Strategy-Free Elections, And The True Measure of a Voting System

If you get involved in the debate on voting system reform, it's never long before someone brings up the concept of "strategic voting." The idea is simple enough: we all want to be as honest as possible on our ballots, but because the voting system is imperfect, we vote otherwise. This is easy to see in plurality; lots of people who claim to really want a third-party candidate end up voting for one of the two major-party candidates on election day. But it happens, to a lesser or greater extent, under all voting methods.

Actually, that's a cleverly-constructed lie of omission.

It turns out that there are a number of voting systems which are 100% strategy-free, so your honest vote will always also be your best vote. But you're not going to like them. Here's an example: voting is performed like plurality, i.e., each voter picks a single candidate. The winner is whichever candidate is named on a ballot chosen at random. Clearly, you should always vote the one candidate you think is best for the job, because there's no reason to fear that you're "throwing your vote away" or making it easier for a candidate you dislike to win. The clever part in the constructing of the lie was omitting the word deterministic, which means "no random components". There are no strategy-free deterministic voting systems.

Constructing other (and better) strategy-free methods is easy enough. So if strategy is so vitally important that it invariably comes up in every voting-system discussion, why don't we use one of them? The answer is: average performance. Random ballot voting, as your intuition probably tells you, is an absolutely terrible system. But intuition is sometimes wrong, so it's important that we can back it up with data by running computer simulations to calculate Bayesian regret. And the data shows that, based on the number of candidates competing, random ballot is two- to four-times worse than plurality voting; which we all know from experience to be a pretty bad system.

Strategy, and a voting system's susceptibility to it, are an important thing to be aware of. But immunity to strategy, even though it sounds like a great thing to strive for, isn't the goal of a voting system; if it were, we'd have an easy answer to the problem, in the form of non-deterministic voting methods. And there are a host of other reasonable-sounding things for a voting system to accomplish, many of which have been codified as voting system criterion. But, besides many of them being mutually-exclusive (i.e., you can't meet them all), using any of them as a litmus test obscures the true objective, in the same way that focusing exclusively on being strategy-free obscures the true objective. The only true measure of a voting system is it's expected performance: how well it delivers a desirable candidate to the electorate. Average performance, as measured by Bayesian regret, smooths over all the coarse edges of criterion, implicitly assessing all of them for frequency as well as impact.

Why should it matter that, for instance, approval voting fails the majority criteria, if the failure rate is vanishingly-infrequent and has minimal impact? When it performs significantly better than a host of other systems that do meet this criteria, but fail some other, equally-reasonable criteria? It shouldn't. Holding the percentage of strategic voters constant, approval voting has significantly better performance than just about any other voting method. Range voting (AKA score voting) can be even better. Which criteria are passed are secondary to that fact.

Thursday, November 4, 2010

How it Might Have Been Different

Sorry for the lack of posting, but my political energy has all gone towards volunteering my time to my favorite candidates. One of those candidates was Scott McAdams, who ran in the race I am about to discuss. I have tried to keep my partisan views out of this piece as best as I can and to refer only to polls and election results in the most dispassionate way possible, but I feel it would be deceptive of me to not acknowledge my connection to the campaign.

Sometimes it's hard to articulate how approval voting or score voting would serve to create better electoral results. The typical election quickly boils down to just two good choices, and despite the rare holdout, most voters begrudgingly accept that they have a binary choice to make. But when there are only two options, every voting system produces the same result; the improvements only come by making more choices viable. Yet, for whatever reason, people have a hard time imagining how a better system encourages more choices, preferring instead to just complain about the lack of options or to simply demand more options, without supplying any mechanism that could encourage such a thing.

Approval voting and score voting are the mechanisms. And this election has actually provided an example to illustrate it: the three-way Alaska Senate race. Thanks to Public Policy Polling, we have some excellent information [PDF] pertaining to the candidate's favorability ratings. Favorability is a pretty good proxy for three-point score voting (where the scores are -1/0/+1). The first thing that jumps out when we look at these numbers, is that Miller and Murkowski had some of the worst favorability scores out of all Senate candidates across the entire country. Miller had 36% favorable versus an astounding 59% disfavorable, for a -23 net, and Murkowski had a 37/53, for a -16 net. But McAdams had one of the best favorability scores in the country, with a 50/30 for a +20 net.

This means that, under this simple score voting system, McAdams would likely have won this race, and it wouldn't have even been close. Under plurality though, he got only 24% of the vote, while Miller got 34% and Murkowski got up to 41% (41% is the total for all write-ins, but polling suggest that about 95% of those (so about 39% of the total) are for Murkowski). Looking at just these numbers it's clear that not only did a large number of Murkowski-and-McAdams approving voters chose to go with Murkowski, but that at least some Alaskans voted for Murkowski in spite of the fact that they did not approve of her.

Clearly, this is an example of tactical voting. No (deterministic) system is completely immune to tactical voting, and we can't be fully certain that voters would have voted precisely how the poll suggest they would have if they knew their favorability opinions would decide the outcome (indeed, some PPP favorability polls would have called narrow two-way races backwards). But, assuming the poll represents honest opinions, we can be certain that a majority of Alaskans (i.e., over 50%) would be disappointed with either a Miller win or a Murkowski win, while about half would have been satisfied with a McAdams win. And yet, the winner will be either Miller or Murkowski, and certainly not McAdams, depending on how many write-ins survive the auditing process.

Plurality voting breaks down when there are more than two good choices. That's why most elections see just two "viable" candidates. But simply adding more candidates (or even more parties) accomplishes nothing, because we don't have a system that can deal with more than two options. We have a two-party political system because we have a two-party voting system. But if we change to a better system, one where we can get better results by adding more candidates, only then can we find success by doing so.