How the NBME 31 score calculator turns misses into a score
Two hundred items and a single line: the NBME 31 score calculator takes 1.08 per wrong answer off 270.48, then rounds.
Both constants are the lowest in the Step 1 set, so the NBME 31 score calculator draws a curve that is simultaneously flat and low.
Each question costs about 1.08 points, the gentlest per miss of the seven, yet the NBME 31 score calculator is still the least generous.
Pass probability comes from a separate logistic curve centred on 196. The NBME 31 score calculator reads 67 per cent at 65 wrong and 46 per cent at 70.
That transition is steep: 65 wrong reads 67 per cent in the NBME 31 score calculator, and 73 wrong reads 33 per cent.
There has never been a public CBSSA conversion table, so the NBME 31 score calculator reconstructs one; see the modelling notes.
On paper it is 1.08 times the wrong count, taken off 270.48 and rounded. No score report reaches the NBME 31 score calculator at all.
Checked by hand: the NBME 31 score calculator gives 233 at 35 wrong, 211 at 55 and 189 at 75.