Why Tornado Diagrams Are Important for Business Communication
Effective communication to decision makers requires demonstrating what matters most and what matters least.
Tornado diagrams quickly show the things that matter most. That makes tornado diagrams one of our most important business communication visuals. Many technical professionals try to over-explain this important visual. Trust that decision makers will intuitively understand without a long, detailed explanation. This article provides some perspectives and tips on communicating tornado diagrams.
The Things That Matter Most
Tornado diagrams are modified versions of a bar chart. They are a classic tool used to communicate the results of a sensitivity analysis, which can be performed either deterministically or probabilistically. The tornado diagram receives its name from the visual image created from wider bars associated with input variables that have more impact on the output being located at the top. In contrast, the narrow bars associated with input variables with less impact on the output are shown at the bottom.
Explaining A Tornado Diagram
It is important to explain a tornado diagram initially to decision makers. I have found the following sequence effective: the input variables are shown down the left side of the diagram; the vertical line running through the center of the bars represents central tendency (usually the median). The bars represent the potential range of variation from the vertical line (central tendency) resulting from that particular input parameter. The input parameters at the top of the diagram are much more important than those at the bottom.
Leaders Understand Tornado Diagrams
From practical experience, after one explanation, most decision makers quickly understand the primary takeaway—things at the top of the diagram are much more important than things at the bottom. It becomes a powerful reference graphic in projects with subsequent phases. It will also be a graphic that will become requested as a standard in other types of reliability, risk, and resiliency projects.
Three Practical Tips
These are three practical considerations for presenting tornado diagrams.
1. Initially View as a Picture
The initial explanation of the tornado diagram can be done in a picturesque manner, meaning that all the input parameters on the left side of the figure do not have to be legible by the audience. It is much more important for decision makers to understand the basic concepts and feel of the "tornado." Subsequent enlargements can drill down into the details of inputs that are most or least important; of course, in the case of enlargements, the input parameters should be legible.
2. Keep It Simple
Tornado diagrams are busy diagrams. Shades of black and blue colors are best for the major components. Use icons of shapes like triangles or diamonds combined with sharper colors like yellow and red to highlight key points.
3. Decision Makers Understand
Decision makers often initially understand them better than their technical advisors. For some reason, mathematical types want to drill down too fast. They want to get wrapped up in the trees without first soaking in the essence of the larger forest. Trust your decision makers and trust your tornado diagrams.
Applying It with FINESSE
FINESSE is the cause-and-effect approach for effective communications with high complexity and uncertainty. FINESSE stands for Frame, Illustrate, Noise Reduction, Empathy, Structure, Synergy, and Ethics.
Tornado diagrams are extremely powerful. They are among six essential graphics that should be included in communications with decision makers. You leave much value on the table if you do not regularly use tornado diagrams.
The illustration "Tornado Diagram" and excerpts from this article are taken from JD Solomon's book, "Communicating Reliability, Risk, and Resiliency to Decision Makers: How to Get Your Boss's Boss to Understand." The 2022 second edition can be purchased on Amazon.