Some exhibits are built to test whether you read them or just look at them. Five traps come up again and again:
- A truncated axis: the value axis starts above zero, so a 4% gap looks like a doubling.
- An indexed chart: lines start at 100. They show growth, not size; a fast-growing small brand can still add less than a slow-growing big one.
- Cumulative totals: a line that only goes up may be adding each year to the last. The yearly number is the step between points.
- A unit change in a footnote: one column in thousands, the next in millions.
- Shares without totals: a falling share can sit beside rising sales.
The habit that beats all five: read the title, the axis, the unit and the footnotes before the shape.