This walks you through the Sean Ellis test for measuring product-market fit: survey users on how disappointed they'd be if your product disappeared, then use that data to build your roadmap. If 40% or more say "very disappointed," you've likely got something. What I like here is it's not just measurement, it's Rahul Vohra's full method from Superhuman for turning responses into prioritization decisions. You need at least 30 active users who've had real time with the product, so it's not for early validation. Best used when you're past initial traction and need to decide whether to double down or pivot, or when your roadmap arguments have devolved into opinion tennis.
npx skills add https://github.com/pmprompt/claude-plugin-product-management --skill pmf-survey