Three-Signal In-Person Validation
Compare words, body language, and behaviour before believing praise
- Difficulty
- Easy
- Time to result
- ~days to results
- Steps
- 4
- Confidence
- 97%
Validate an offer by observing target users experience it in person, then compare three signals: what they say, how their body language changes, and what they spontaneously do or ask next. Praise from friends, family, or remote respondents can be sincere but socially biased; direct observation reveals whether enthusiasm is embodied and behaviourally credible. When all three signals repeatedly align—such as visible delight, specific praise, and an unsolicited desire to buy or learn more—the evidence is stronger. Koerner distinguishes ordinary positive feedback from the rare feeling of demand pulling the business forward. The method does not prove scalable product-market fit by itself, but it provides a fast qualitative gate before investing in larger production or acquisition tests.
Origin
Extracted from The Diary of a CEO
Core principles
- 01Observed reactions reveal more than polite feedback
- 02Words are strongest when behaviour agrees
- 03Strangers provide cleaner evidence than supportive friends
- 04Strong demand feels like pull rather than persuasion
How to run it
- 1
Recruit relevant strangers
Find people who resemble the intended customer and have little reason to protect your feelings.
Pro tip Use a market, event, or other natural context where the product belongs.
Watch out Convenience samples may not represent the wider market.
- 2
Let them experience it
Present the product with minimal coaching so the reaction is to the offer, not your sales performance.
Watch out Follow appropriate safety and consent requirements.
- 3
Capture three signals
Record their words, visible reaction, and spontaneous actions or follow-up questions.
Pro tip Write observations immediately rather than relying on memory.
Watch out Do not diagnose motives from body language alone.
- 4
Look for repeated alignment
Treat consistent overlap across the three signals as a stronger validation signal than compliments alone.
Pro tip Follow with a purchase or commitment test when possible.
Watch out Enthusiasm is not yet proof of profitable acquisition or retention.
In the wild
Koerner and his wife offered samples of her cookie bars at a local farmers' market. They compared what people said with their visible reactions rather than relying on positive messages from friends and family who received shipped products.
→ He describes the aligned reactions as validation that customers genuinely loved the product.
Common mistakes
Surveying only supporters
Friends and family may give encouraging feedback that does not predict buying behaviour.
Reading body language as certainty
Nonverbal cues are ambiguous and should corroborate, not replace, words and behaviour.
Calling delight scalable demand
Qualitative validation still needs pricing, acquisition, and retention tests.
Is it for you?
Best for
Products or prototypes that target users can experience directly in a short session.
Not ideal for
High-stakes products whose value appears only after long-term use or controlled clinical evaluation.
From the transcript
“You want to take note of what they say and take note of their body language and how they react.”
“If all three of those things overlap, then... you have something really special on your hands.”
From the episode
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