A good model can be useful even when it fails

As the rains from Hurricane Sandy fall around us here in Central Pennsylvania, I'm checking out various computer models about the track of the storm, and am reminded about this quote from Nate Silver's great book on predictions, "The Signal and the Noise: Why So Many Predictions Fail-but Some Don't":

A good model can be useful even when it fails. "It should be a given that whatever forecast we make on average will be wrong," Ozonoff told me. "So usually it's about understanding how it's wrong, and what to do when it's wrong, and minimizing the cost to us when it's wrong."

The key is in remembering that a model is a tool to help us understand the complexities of the universe, and never a substitute for the universe itself. This is important not just when we make predictions.

This storm tracking graphic is a model. Outside, the rain is falling and the wind is beginning to blow. That's reality.

Source: National Hurricane Center