Riskiest assumption: what it is and what it means

A riskiest assumption is an untested belief that, if wrong, brings down the entire business model. You identify it by crossing two dimensions: the risk of the assumption (how serious it is to be wrong) and the evidence available (how much you already know, and how solidly). Assumptions with high risk and low evidence available are the ones that require priority testing. Three typical categories that founders tend to take for granted: that the customer is willing to pay, that the channel can be reached at a sustainable cost, that the unit cost falls with scale.

Distinctive: brings down the entire business model
Distinctive: high risk and low evidence available
Essential: untested belief
Essential: risk of the assumption
Essential: evidence available
Constant: priority testing
Constant: founders tend to take for granted

Glossary

Riskiest assumption

An untested belief that, if wrong, brings down the entire business model — to be told apart from assumptions with little bearing on whether the idea fails.