About six months ago, we received word from one of our PMP prep students that he had a strange weather topic appear on his PMP exam, something like a “hurricane chart” or something. After a bit of investigating and confirmation with the student, in all probabilities, he had a question on a tornado diagram.
While not surprising to see this come up on the PMI Risk Management Professional (RMP) exam, it was a little surprising to see it come up on the PMP exam. Since that time, we’ve had a good majority of our PMP students mention getting a question on tornado diagrams.
So what exactly is a tornado diagram? And what does it have to do with risk?
It’s essentially a bar chart where the data categories are listed vertically instead of horizontally and then the occurrences are ordered with the largest one on top, in decreasing order – thus given the image of a tornado.
Only mentioned briefly in The PMBOK Guide in the Perform Quantitative Risk Analysis process, the tornado diagram is referenced as a method for displaying a sensitivity analysis by “comparing relative importance and impact of variables that have a high degree of uncertainty to those that are more stable” (The PMBOK Guide, 4th Edition. PMI. (C) 2009)
Given the apparent popularity on the test (well…. maybe popularity isn’t the best word, after all, it’s only one question out of 200) PMP students should at least be familiar with the concept of a tornado diagram – but probably not much more than knowing it’s related to a sensitivity analysis in the Perform Quantitative Risk Analysis process.