I also attended his seminar in 2001 and it heavily influenced my life and work. As an example, when my wife was giving birth to our second child I made a plot, a simple one with paper and pen, of the time between contractions. I did that because the first time they tried to hurry her along with drugs. The second time when the doctor came in to whine that we were “not making progress” (read: the doctor has dinner reservations at 6) I was able to show convincingly that progress was indeed steady. The simple act of visualizing data can influence decisions, which is the point of his chapter on the Challenger disaster.