09
Does the number have context?
A number with nothing to compare it to says almost nothing.
Why it's a trap
Numbers have a superpower: they look objective. “87%” sounds precise, scientific, and yet a number can mislead without being false. It just needs to be pulled out of context: “the risk doubles” (from 1 in a million to 2 in a million), “thousands of cases” (out of how many millions?), “+100%” (starting from almost nothing).
You don't need to be good at maths to defend yourself. Three questions are enough, always the same: how much at the start? Out of how many in total? Who counted, and how? An honest number takes these questions very well. A rigged number hates them.
The moves
- Find the starting point: a percentage change without the initial value is a stage trick.
- Bring it back to scale: “thousands” in a town or across a continent are two different stories.
- Ask who measured: a poll has a sample size, a method, a sponsor.
- On a chart, look at the axis: does it start at zero? Spectacular bars are often born from a cropped axis.
The classic trap
“Incidents up 50% in the neighbourhood!” The next line, which nobody reads: they went from 2 to 3. The headline is accurate. The impression it leaves is not.
Keep in mind
A number without context is a costume.
Practise this reflex
Cases in the library train precisely this reflex:
- What should you do before sharing this? (Health & miracle cures)
- What's the trap here? (Health & miracle cures)
- What's the problem? (Health & miracle cures)