The results of the analysis in the classic method showed that the regression indexes were influenced when
respectively the forms of A and B were the references, in a way that with the results driven from the first state was
significantly different from the results of the second one. The results showed that in the classic method equating is
dependent to the observed sample, insofar as the observed sample being changed, the mean and standard division
from the two samples for a test were significantly different. IRT can resolve two limits of classic method, symmetry
and invariance.