To really understand risk, you need to have a complete grasp of type of problems that can happen on a project, how to mitigate them, and possible contingency plans. To know which risks items are the most appropriate, you need to know the chances that each one will occur. That means you should understand probabilities and statistics. That is always dreaded. This simple educational tool can be used when reading Chapter 19 to help understand some of the concepts. It contains and Excel template (with macros) and a conceptual document to show its limits.