Adaptive Testing with Equated Number-Correct Scoring

A constrained computerized adaptive testing (CAT) algorithm is presented that automatically equates the number-correct scores on adaptive tests. The algorithm can be used to equate number-correct scores across different administrations of the same adaptive test as well as to an external reference test. The constraints are derived from a set of conditions on item response functions that guarantees the observed number-correct score distributions on two forms to be identical (W. van der Linden and R. Luecht, 1998). An item pool from the Law School Admission Test is used to compare the results of the algorithm with those for traditional observed-score equating of ability estimates to number-correct scores as well as the transformation to predicted number-correct scores through the test characteristic function. The effects of the constraints on the statistical properties of the ability estimator are examined. (Contains 18 references, 4 figures, and a list of University of Twente research reports.) (Author/SLD) ******************************************************************************** Reproductions supplied by EDRS are the best that can be made from the original document. ********************************************************************************