Product-market fit measurement framework

Measure and achieve product-market fit using multiple signals. PMF indicators: 1. Sean Ellis test: >40% of users would be 'very disappointed' if they couldn't use product anymore. 2. Retention curves: cohorts flatten to horizontal line (not declining). 3. Organic growth: word-of-mouth driving 30%+ of new signups. 4. Usage intensity: users engaging multiple times per week. 5. Net Promoter Score >50 and growing. Measurement cadence: survey users quarterly, analyze retention monthly, track referrals weekly. Early PMF signs: customers pulling product from you, usage growing organically, positive unit economics emerging. Pre-PMF: focus on retention over growth. Post-PMF: optimize growth engines. Tools: Amplitude for retention, Delighted for NPS, internal surveys for disappointment test. Document learnings about ICP (ideal customer profile) refinement.