Visualization: Shapes Often Distort the Truth

What is the appropriate width of a bar in a bar chart? As thin as possible - it's a one-dimensional shape (a line).

Shapes lie when they represent numbers using the wrong dimension. A circle, square, or triangle scaled by width instead of area misleads readers who compare two data points at a glance. As a result, the reader walks away with the wrong impression of the underlying numbers. The distortion happens whether the mistake is careless or calculated.

Area Fools the Eye Faster Than Length

The human eye judges shapes by their total area. When a shape's dimension is scaled directly to a data value rather than to its square root, the visual difference between two figures balloons far beyond the actual difference between them. A modest gap in the underlying numbers can look enormous on the page. Readers usually trust what they see, which is exactly what makes this error so effective at misleading an audience.

Fix the Math or Skip the Shape

If a shape must carry the comparison, scale its dimensions to the square root of the value, not the raw number itself. That single adjustment keeps the visual proportion honest.

However, the simpler fix is to skip shapes altogether for one-dimensional comparisons and use a bar chart instead. Bars encode a single value along a single axis, so no dimension is left to distort and no square root to remember.

The Tip - Shape Visualization

The tip is to avoid deceptive shape scaling. Check whether a shape's size was scaled correctly. A good visual should clarify a comparison, not exaggerate it.

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JD Solomon is the author of Communicating Reliability, Risk & Resiliency to Decision Makers: How to Get Your Boss’s Boss to Understand and Facilitating with FINESSE: A Guide to Successful Business Solutions.