He means the self-assessments offered by the NBME which can be purchased from the nbme website......they have a high correlation (0.6) with your actual score.
Scored a 238, 96 on Step 1. I studied Crush the Boards (Excellent source) for 1-2 hrs per day and did Q bank for 4-6 hrs per day. Average Q bank score was 80-85%. Studied for a total of 14 days. Step 2 CK score was 264, 99