Bill James shares his method to determine when a college basketball game is out of reach.

Previously published Slate articles made new.
March 18 2009 7:03 AM

The Lead Is Safe

How to tell when a college basketball game is out of reach.

Also in Slate, Josh Levin runs through the Teams We Hate in this year’s bracket, and Chris Wilson explains a system that will help you win your NCAA pool.

There are five minutes to go and your team has a 15-point lead. You start to flip the channel but then have a moment of doubt—is there a chance that the other guys could come back and win? From now on, you'll never have to wonder. Last year, Bill James, a lifelong Kansas Jayhawks fan, shared his personal formula to determine when a lead in a college hoops game is safe. If you're thinking about switching to another game during March Madness, just keep this page open and plug the current score into the Bill James Lead Calculator. The piece is reprinted below.

Tyler Hansbrough #50 of the North Carolina Tar Heels. Click image to expand.
Tyler Hansbrough

Question: How do you know when the contest is not officially "over," but the outcome is no longer in doubt?

Answer: How would I know? I was a Huckabee guy.

With apologies to the Sage of St. Louis, there comes a time when it ain't over, but ... it's over. There comes a time in a relationship when a woman will still answer your phone calls, but you're wasting your money buying flowers; you know what I'm saying? There comes a moment during a job interview when you're still talking, but you might as well take off your shoes. There is a time in an illness when you're not dead yet, but you might as well stop taking that nasty medicine.

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There is a line there somewhere, and how do you know when the line is crossed that separates hope from fantasy? If we're talking politics, romance, job interviews, or medicine, I don't know. When it comes to college basketball, I've got a theory.

This thing has a 40-year history, actually. I've been attending basketball games at Allen Field House in Lawrence, Kan. (home of the Jayhawks), since 1967. The Jayhawks usually win by 15 or 20 points, and sometime in about 1968 I started wondering whether there wasn't some way to decide when the game was no longer in doubt. I began to experiment with heuristic inventions to try to find the moment at which the line was crossed. A heuristic could be loosely defined as a mathematical rule that works even though no licensed mathematician would be caught dead associating with it.

Let's see ... what about: The game is over when the number of points you are ahead (or behind) is more than one-tenth the number of seconds left in the game? *

Nah, that doesn't work. If you're 30 points behind, the game is over much more than five minutes out (300 seconds); if you're two points behind, the game is not over when there are 20 seconds left. The rule doesn't work on either end.

Eventually I found a rule that did work at that time, but at that time there was no 3-point shot in basketball. When they added the 3-point line, I had to recalibrate my system.

OK, I've stalled as long as I can. You ready?