The short answer
Test one uncertainty at a time. Ask about recent behaviour, run a small trial and record what people actually do. Compliments and likes are not the same as repeat use or willingness to pay.
- 01Assumption
What needs to be true?
- 02Test
What action can show it?
- 03Observation
What actually happened?
- 04Decision
What changes next?
Turn an idea into questions
A useful first test checks one uncertainty. Do people experience this problem? Can you reach them? Will they use the proposed solution? Can you deliver it at an acceptable cost? Write each question separately so that positive feedback on one does not become “proof” of all the others.
Ask about behaviour, not compliments
- “Tell me about the last time this happened.” Follow up on what the person did, the time it took and what remained unresolved.
- “What do you use today?” Include doing nothing, borrowing, informal help and competing services.
- “Who decides and who pays?” Avoid asking someone to predict another person’s purchasing decision.
Ask permission before recording. Keep only the notes you need. Do not put names, phone numbers or sensitive personal stories into a public case study without appropriate permission.
Choose a test with an observable result
Use a sketch, a sample session, a demonstration or a manually delivered service where suitable. Decide in advance what you will count: attendance, task completion, repeat use or another relevant action. A social-media like and a paid order are different signals.
For an illustrative pilot, invite ten students who have an interview coming up to try a free booking prototype. Before starting, decide that at least three must finish a booking without assistance by Friday. If only two finish, the criterion was missed even if eight praised the idea. Watch where the others stopped, revise that step and run another small test before buying stock. This tests one part of usability and follow-through; it does not prove paid demand or represent the entire market.
Keep the result honest
Record people who declined, dropped out or could not use the solution. Compare the result with your original question. If the test failed, identify whether the problem, audience, price or delivery needs to change. Avoid collecting more favourable comments merely to defend the original idea.
This worksheet is an editorial exercise. For structured introductory study, Startup India’s learning programme includes idea validation among its topics.
Worked example: what counts as evidence?
Suppose you are testing a reusable-notebook service for a college club. Ten friends saying “nice idea” tells you that the idea sounds attractive to those friends. It does not show that a club can approve a purchase, that the notebook survives repeated use or that the price covers replacement costs. Test those questions separately. The figures and project here are illustrative.
| Signal | What it helps you learn | What it cannot establish |
|---|---|---|
| An interview | A person’s recent problem and alternatives | Demand across the market |
| A prototype trial | Where use or delivery breaks down | Repeat purchase |
| A repeat order | Continued use by that customer | Profit after all costs |
Make a test sheet before you begin
Use a second test to investigate the most important surprise. If people attended a free session but would not pay, ask what they valued, what they expected to pay and who has a budget. Do not quietly change your original success criterion and then call the same test successful.
Check your understanding
Ten people liked my idea. What should I test next?
Choose an action tied to the uncertainty: trying a prototype, completing a task or placing a genuine order where appropriate. Ask who actually uses, decides and pays.
Can a small sample tell me the size of my market?
Not reliably on its own. Record how people were selected and what the test can show. Use the result to plan a better next experiment.
Sources & further reading
Updated 20 September 2026. Open the issuing authority’s page for current rules, fees and course availability. Examples and worksheets are PLS Foundation learning exercises; legal and financial decisions may need qualified advice for your circumstances.