Ch. 4
4 of 1 ·Percentages Need a Base
Chapter 4 · Numbers Tell Stories
Lesson 4 · Numbers in Context
Percentages Need a Base
Translate dramatic percentages back into actual counts.
Easy~25 minFree preview
Concept
A percentage hides its denominator
A 100% increase sounds enormous, but it can mean a change from one case to two. A percentage becomes meaningful only when you know the starting value, total group and time period.
Example
The club that doubled
Click to zoomIllustration supporting The club that doubledA headline says membership doubled. If membership rose from 2 to 4, the percentage is correct but incomplete. If it rose from 200 to 400, the practical scale is very different.