Axes Can Lie
Is that a cliff, or is it the axis?
The idea
Truncating an axis, changing its scale or choosing the window makes the same data look dramatic or flat.
In the real world
A 2% change filling a chart because the axis starts at 98.
Going deeper
Most misleading charts contain no false numbers at all. The distortion is in the framing: a truncated vertical axis magnifies small variation, and a window starting at a peak turns normal movement into a decline.
Both are legitimate in some contexts, which is what makes them effective. Truncating an axis is reasonable when small changes genuinely matter; choosing a start date is unavoidable. The defence is simply to read the axis and the date range before reading the shape, because the shape is the part designed to persuade and the axis is the part that determines what it means.
Where it stops applying
Insisting every axis start at zero is its own distortion, flattening genuinely important variation. The requirement is disclosure and appropriateness, not a fixed rule.
Why it matters
Most misleading charts contain no false numbers at all.
Try this today
On the next chart you see, read the axis before the shape.
Test yourself
A chart shows a dramatic collapse. Every value is accurate and nothing is fabricated. How was the impression created?
Show the answer
Through the axis and the window: a truncated vertical scale magnifies small variation, and a start date chosen at a peak turns normal movement into a decline. The data is honest and the framing carries the argument.
Learn this in the feed Answering from memory, then again days later, is what makes it stick.