Product-Market Fit Stress Test

Most founders think they have PMF because customers exist. But customers exist because the founder pitched them — that's salesmanship, not product pull. PMF is what happens when strangers find the product, pay for it, stay, and tell others without prompting. This skill runs the seven-question stress test that separates the signal from the founder's optimism, and grades each answer Strong, Weak, or Missing with the evidence required to defend the score.

The tests run across the dimensions that matter. The Sean Ellis disappointment test (would 40%+ of users be "very disappointed" if the product disappeared?). Organic pull (are customers finding you or are you finding them?). Retention. Willingness to pay without discounting. Switching cost. Word of mouth. Segment clarity — "SMBs" or "marketers" fails the test because it's too broad to be actionable; "operations managers at UK construction firms with 50-200 staff" passes. The weakest answer is the biggest risk, and that's where the next experiment goes.

The skill is rigorous, not encouraging. Telling a founder they have PMF when they don't wastes their money and time, and the consequence — a scaled-up acquisition motion against a leaky bucket — is more expensive than the honest diagnosis would have been. The skill grades honestly, names what's missing, and won't accept "our customers love us" as evidence. Have you surveyed them? How many said "very disappointed"? If you don't know, that's a Missing, not a Strong, and the next step is the survey.

The output is a graded scorecard, a diagnosis from the four defined categories (pre-PMF, approaching PMF, PMF achieved, false PMF), the named weakest link, and at least one specific validation experiment with a falsifiable hypothesis and clear kill criteria. There's also a section on what to honestly tell investors — because the founder will be asked, and a calibrated "we have early signal in this segment, here's what we're still testing in that one" lands better than a confident claim that falls apart under three follow-up questions.