So what you are saying is that a PSAT percentile should be about the same as an IQ percentile?

The reason I ask is because I took the NMSQT in Fall 2016, and I received a score of 1250 on it. Since the test score can be converted to the PSAT 8/9, I would be receiving a 98th percentile score (national) if I had taken it as a 9th grader. This score is Mensa eligible, while the former one you mentioned (97th or 128) isn't.