murphyle

ATI leveling isn't based off percent score, but percentile - where you are in relation to the national and program mean scores. For example, you might score a 71% individual, but if the national mean is 61%, you're still way ahead of the curve, and your mastery level will reflect that. Looking at my own ATIs, I'd say it's pretty accurate to say that a Level 3 requires a percentile ranking in the 90s, but that doesn't mean you need a 90% score. (I recall seeing my results on several ATIs and absolutely losing my mind, thinking I'd failed, before I realized that the national mean was significantly worse - hence I still pulled a high mastery rating with what I thought was a horrid individual grade!)
Hope this helps!