Westerman Road Rage: Behind the Numbers

Mad props go to Larry Bednar, the Northeast Portland statistician who came up with the killer stat in our story this week about Sgt. Scott Westerman's twin road-rage cases.

Bednar spent part of his weekend calculating the odds that Westerman would randomly encounter the same vehicle at opposite ends of the metro area — once off I-205, and again two days later on the Beaverton-Hillsdale Highway. Both times, Westerman got out of his car to yell at the driver.

Bednar's conclusion — which he emphasizes is a very rough estimate — puts the odds of the second encounter at one in 2 million. That's the same as the chances of flipping a coin and landing heads 21 times in a row.

To provide a geeky window into Bednar's reasoning, we're posting a copy of a three-page report (PDF) he generated walking us through the numbers. Bednar said given the nitpicky nature of mathematicians, he wouldn't be surprised if other stats junkies take issue with some of his conclusions.

Have at it!