So this is where it all began. I first saw a Crystal Ball forecast chart in the summer of '94 and it changed how I thought about the world.

Thinking in Ranges. No longer could I just see a number, but rather I could see the range around the number. How different would it have to be for me to make a different decision?

When I received an MBA, I especially liked spreadsheets and NPV calcs. Of course, the whole point of NPV is what is the probability that NPV>0? With just Excel, you can only see Possibilities, not Probabilities. With Crystal Ball you can see that left, red tail. That is the key to understanding a project's risk and uncertainty.