Last night I watched a 60 minutes interview with Chris Martin, lead singer of a popular band called Coldplay. They won three Grammys last night.

But the interesting part for me was what Chris said about how he judges the success of a new song. When he’s onstage performing, he can’t really see the crowd but he can clearly see the exit signs. When he starts a new song, he checks the exit doors to see how many silhouettes are in the doorway. If the doorway is empty, it means no one is leaving, and that indicates his song is a winner.

This is how …