List and rank the assumptions behind an idea so you test the riskiest one first.
When to use itAfter choosing a solution direction and before committing engineering time.
Desirability
Do customers want this? Will they change behaviour to get it?
Viability
Can the business make money from it or justify the cost?
Feasibility
Can we build it with the team, time and technology we have?
Usability
Can customers work out how to use it without help?
Plot and pick
Place each assumption on a grid of importance against evidence. Test the important ones with the least evidence first.