Think Better · 55 sec
Always Look for the Denominator
‘100 people were affected’ is incomplete information.
The useful idea
- Understand
A count becomes a rate only after it is compared with the population that could have been affected.
- Connect
One hundred cases among one thousand people represents a different risk from one hundred among ten million.
- Apply
The relevant denominator must match the place, period, and group described by the numerator.
Why this matters
Large counts can sound alarming without revealing whether the underlying rate is large or small.
Try this
Ask: ‘Out of how many?’
Test your recall
Which action best applies “Always Look for the Denominator”?
- Compare your estimate with how long similar tasks actually took.
- Change the two most uncertain assumptions across plausible ranges and note where your preferred option switches.
- Ask: ‘Out of how many?’ — correct
Large counts can sound alarming without revealing whether the underlying rate is large or small.