I built PD.Radar because of one number: 540
I built PD.Radar because of one number: 540. That's how many comments a 524-point HN thread had, all answering the same question — "what's the best money you've spent on professional development?" — and no one had ranked the answers. I mined all 540, matched every resource people named (books, courses, tools), and ranked them by how many commenters actually cited each one. Therapy won, 51 citations. Not upvotes, not vibes — citations.
The rule I use: only threads with 300+ points, specific answers (people name things, not "read more"), and 200+ comments qualify — otherwise the ranking is noise. The 540-comment pass took 4 hours the first time; the pipeline is a script now, so the next one takes ~30 minutes.
The site is live — https://justinnnnnnn045.github.io/pd-engine/ — and the newsletter is where I'm posting the next-ranked thread as free analysis. If you're a founder who has a big "question thread" in your niche with answers nobody has ranked, that's exactly what this finds.
The ranking methodology is interesting, but the stronger signal is what happens after people see it. Have readers actually changed a purchase or professional-development decision based on one of your rankings?
Honest answer: not yet — and you're pointing at the exact metric that matters. Citations prove what people mention, not what they choose, and I haven't instrumented the choice part. That's on me.
So I'm shipping the missing piece this week: a one-click "this changed what I decided" button on each ranked resource, plus a follow-up email to everyone who's opened the page asking the same thing. The first verified "changed my decision" story gets pinned to the top of the leaderboard, with the thread link so anyone can audit it. That's the only proof I'll advertise.
If you want, you can be the first person to break it.