Two sigma

Derrick is on his way to Oregon, from whence he will leave on a research cruise for about a week. While we were driving to the airport, Derrick suggested that instead of giving speeding tickets for going over the speed limit, speeding tickets be given for going more than two sigma over or under the average speed of traffic (that being, theoretically, the speed suggested by the current speed limits). I could just envision a world where, under the speed limit sign, you see a histogram of the speeds of other drivers on the road, and from that calculate where your speed lies on the distribution. I'm so glad my husband is a nerd.