What is baseline bracket prediction performance?

I’m here to tell you right now that nobody has a failsafe system for predicting the NCAA basketball tourney. As Nate Silver might say, filling out your bracket is an exercise in assessing probabilities. You’re not going to build a perfect bracket. Not going to happen. There are nine quintillion different bracket combinations (two to the 63rd power or 9,223,372,036,854,775,808 to be exact). Sure, a lot of them—like a Final Four of all 16 seeds—are patently absurd—but even the number of plausible outcomes is astronomical.

Fortunately, your task is not to build a perfect bracket. It’s just to win your bracket pool. Most people play in pools of 20 to 200 people. These pools are typically won by someone who gets between 48 and 54 correct picks out of the 63 tourney games. That works out to about a 75-85 percent accuracy rate. If that seems lower than you expected, remember that inaccurate picks in early rounds reduce the number of later-round games in which you even have a chance to be right. So three out of four actually ain’t too bad.

If 48 out of 63 is the benchmark of winning bracket performance, what constitutes average tourney prediction success? When you consider that even the most clueless bracketeer could adopt a strategy of advancing the higher seed in all match-ups, then that should stand as the baseline for tourney prognostication. In this case, every top seed would reach the Final Four. To determine winners in the semis and finals, it would be reasonable to advance the team with the higher victory margin, since statistics show that this is the best tourney performance indicator besides seeding.

I went back over the last 28 tourneys of the 64-team era and figured out how well the “higher seed/bigger margin” strategy would’ve done. Here’s the year-by-year breakdown:

2013_BS_baseline

The numbers show that you should be able to predict about two-thirds of the 63 tourney games correctly without even thinking about it. In fact, the baseline bracket picking strategy would’ve correctly identified nine of the 28 champions in the modern tourney era, including Kentucky last year, North Carolina in 2009, Kansas in 2008, and Florida in 2007. That’s four for the last six. Heck, if you had used the higher seed/bigger margin strategy in 2008, you would’ve correctly pegged the Final Four, called both the finalists—and picked the winner.

Of course, this kind of late-round accuracy is an anomaly. Before 2008, all four top seeds had never reached the Final Four. And let’s face it: picking your bracket solely by seeding isn’t exactly a winning strategy. Using this approach would likely put you in contention for average-sized pools in only two of the 28 years—in 2007 (49 correct answers) and in 1993 (48 correct answers). If you were playing in a smaller pool, maybe you’d be among the leaders in 2008 and 2009 as well.

Look no further than last year’s dance for proof that seeding alone won’t get you very far in your pool. Sure, picking Kentucky might’ve helped you land in the upper tier of your pool. But 41 correct picks out of 63 games is actually below average prediction performance. And 2010 and 2011 saw the worst two-year stretch of chalkiness since the 1989-90 tourneys.

There’s no denying that seeding is the single best determinant of a team’s tourney fate. It doesn’t take a bracketmaster to figure out that the one, two, three and four seeds have accounted for 96 of the 112 Final Four teams and 26 of 28 champions in the 64-team era. The real the question is: which factors beyond seeding help improve your ability to predict tourney outcomes above the baseline accuracy of 65 percent? Over the next few weeks, we’ll be examining the relative values of a whole host of attributes. I’ll post some individual blogs about my research, but the full analysis will only be available to Insiders under the Tips section.

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