Purpose: Document evidence collected for each high-risk assumption. Actively seek disconfirming evidence — not just confirming evidence. A well-tested assumption that survives challenge is more valuable than an untested assumption that was never questioned.
Evidence source hierarchy: Direct org data or structured interviews (High) → Analogous programs or research literature (Medium) → Expert estimation or inference from principles (Low). Document source and confidence for every entry. Seek evidence that challenges the assumption, not just evidence that supports it.