John's Rasch score is 1.3. Item A's item difficulty is 0.3. What is the probability of John's getting item A correctly?
Step 1: Substract item difficulty score from person measure:
1.3  0.3 = 1
Step 2: Enter an conversion function (logit > probability) into an Excel cell.
=EXP(1)/(1+EXP(1))
So John has a success probability of 73% when solving item A.
