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Oct 312009

Knowing Win Probabilities is necessary to have a shot at winning your office pool, but it’s not sufficient. It’s not sufficient because Win Probabilities are an open secret: your friends in your pool know them, too. And they’re everywhere, and the best ones are free. Even if they weren’t everywhere, you could estimate your own to a very high degree of accuracy by looking at Vegas money lines. You don’t even have to visit betting websites to see Vegas lines; they’re available in USA Today in plenty of time for you to make your picks.

This is why I make my Win Probabilities available for free as a convenience to my visitors. Mine are based on a generic formula derived from Vegas lines. Other estimates of Win Probabilities, Power Indexes, or rankings abound — one of the longest lived and best known is Jeff Sagarin’s Predicted Points model on USA Today. Brian Burke’s WinChance estimates are made available on the New York Times website after a few weeks into the season, and his record is enviable. I wouldn’t discourage anyone from using them; both are very impressive. But over time, I expect sports bettors and books learn which models work the best and their lines gravitate toward the best models anyway.

The fact that your friends know about Win Probabilities, point spreads, or power rankings means that everyone in your pool will pick mostly favorites, most of the time, and if it’s a confidence pool they’ll rank the teams in descending order by Win Probability. Therefore, most of their pick sheets will look remarkably similar. You need to stand apart.

Predicting upsets is a futile exercise in guessing random outcomes. You can either waste your energy trying to predict upsets, or you can focus instead on which upsets, if they occur due to randomness, will help your picks stand apart. So you need to consider the joint distribution of game outcomes and participant picks. By selectively choosing an upset or two, you can let randomness do your work and when those upsets occur, you will stand apart in your weekly pool results.

 Posted by on October 31, 2009 at 11:50 am