provided a comforting estimate, they were just that—estimates. The official NBME scores are "equated," meaning they account for the specific difficulty of the form Alex just took.
Compare this to NBME 10, where a 196 might require only 60% raw correct. Again, NBME 9 is tougher. nbme 9 offline score conversion
This "add 10 points" heuristic is too crude. If you scored 200 on NBME 9, your real score might be 210. But if you scored 230, your real score might only be 235. The underprediction is most significant in the passing range (190-210) and negligible in the high range (240+). provided a comforting estimate