a numeric value for the probability of a correct response for item i given
that no attributes have been mastered.
r.ia.star
a numeric 1 x nattributes vector of the penalty probabilities for this item of a correct response
for each required attribute that has not been mastered.
q.ia
a numeric 1 x nattributes vector of the qmatrix entries for the given item.
alphas
a numeric 1 x nattributes vector with a 1 if a student has mastered an attribute and 0 otherwise.
Value
the numeric value representing the probability of a correct response for the ith item.