Estimation
Quick, structured estimates beat both guesses and paralysis. Breaking a quantity into parts you can estimate gives answers that are good enough to decide.
Key ideas
- Decompose a big unknown into smaller knowable parts.
- Round numbers keep the reasoning visible.
- Ranges are more honest than single numbers.
Step by step
- 1
Define exactly what you are estimating.
- 2
Break it into factors you can estimate.
- 3
Estimate each with round numbers and multiply.
- 4
Sanity-check against any known reference and state a range.
Example
Estimating how many coffees a hospital café sells daily: about 2,000 staff and visitors, perhaps one in four buy one, so roughly 500, likely between 300 and 800.
Your drill
Estimate how many hours of meetings your organisation holds each week, showing every factor.
Common mistakes
- False precision such as 517.3 instead of about 500.
- Skipping the sanity check.
Check yourself
Why give a range instead of a single number?
Show the answer
It communicates uncertainty honestly and helps others judge how much to rely on the estimate.
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