10+ Year Member
15+ Year Member
Feb 8, 2002
Someone please help me out with this. I am terrible at statistics.

Could someone please show me how to compare scores from the NBME and the USMLE.

Example: Johnny gets a 570 on the NBME self assessment. He is relieved to find out that he has scored above the mean, but when he asks himself what his score would equate to on the real thing he becomes irritated and confused. The mean on the self assessment is 500 with a standard deviation of 100. If the mean of USMLE step1 is 216 with a standard deviation of 24, what score on step1 is equivalent to a 570 on the NBME?

I've heard z-scores are involved so I figured I'd consult the experts...

For full credit you must show your work.


Of course, let's not all place TOO much emphasis on the NMBE practice tests. Everyone wants to know, "if I score x % in QBank, or y % on the NMBE exam, or z % in BSS, what will I get on the real thing?" Obviously there's no way to predict how you'll do. The very fact that the actual test is 8 hours long kinda diminishes the value of the (shorter) practice tests.

Al Pacino

Senior Member
7+ Year Member
15+ Year Member
Aug 15, 2002
Status (Visible)
ok, here goes. Johnny scores 570. His score was mean(500)+ 70% of standard deviation (SD=100) or 500 + 0.7 x 100 or 570.

Ok, let's apply this correlation to the boards. Johnny's projected board score would be mean + 0.7 x SD or 216 + 0.7 x 24= 216+ 16= 232.
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Originally posted by Jalby
I thought the Standard dev for the boards was about 16?? Am I mistaken??

On the one that I took (last June), mean was 217, standard deviation was 24. The standard deviation was smaller a few years ago.
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