Product Development
Riskiest Assumption Test
List what must be true for your idea to work, rate impact and uncertainty, and find the one assumption to test first.
- Time: 30 to 60 min
- With: Founders or product team
- You get: A ranked assumption list and a cheap experiment for the riskiest one
How to use this worksheet
- Write down everything that must be true for the idea to work: who the customer is, what they will pay, whether you can build it.
- Rate each: impact if you are wrong (1 minor, 10 critical) and uncertainty (1 proven, 10 unknown).
- The top-right of the map holds assumptions that are both critical and unknown: test those first.
- For the top one, write the cheapest experiment that could prove it wrong and what result would change your mind.
Assumptions
Impact if wrong (1 to 10) and uncertainty (1 proven to 10 unknown).
Prompts
Ask yourself
- Which assumption, if wrong, makes the whole idea worthless?
- What evidence do you really have, and how strong is it?
Assumption map
Before you finish
- Assumptions are testable statements, not hopes.
- The top assumption has an experiment and a pass/fail threshold.
- The experiment is cheaper than building the product.
About assumption testing
Every business idea is a stack of assumptions. Assumption mapping, popularised by David Bland and Alexander Osterwalder in "Testing Business Ideas", makes the stack visible so you test the weakest part first.
The cheapest valid test beats the most elegant one. A conversation or a fake door page can disprove an assumption in a day.
Recommended reading
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- Testing Business IdeasDavid J. Bland & Alexander Osterwalder
A library of 44 experiments for validating assumptions cheaply — the perfect companion once you've found your riskiest one.
- Running LeanAsh Maurya
A systematic process for identifying and de-risking the parts of your business model that are most likely to fail.
- The Lean StartupEric Ries
The build-measure-learn mindset behind testing your riskiest assumptions before scaling.