Track · 2:30 · Liner note
The Y-Axis Keeps a Secret
A chart's y-axis range changes how large a difference looks, and truncating it, especially on a bar chart, can exaggerate small changes, so the baseline has to be chosen honestly.
Start a bar chart’s axis at 92 instead of zero and a two percent dip looks like a cliff. The y-axis is where a chart keeps its secrets: the baseline, the scale, the range that decides how large a difference feels. The Y-Axis Keeps a Secret is a reminder to check it before you believe the picture.
Bars encode length, so start them at zero. Lines encode change and may zoom, if the axis is labeled clearly and the zoom is deliberate. When a truncated axis is unavoidable, say so on the chart and let the numbers appear beside it.