A constrained 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 test forms to be identical (van der Linden & 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.
|Name||OMD research report|
|Publisher||University of Twente, Faculty of Educational Science and Technology|
- Optimal Test Assembly
- 0-1 Linear Programming
- Item Response Theory
- Computerized Adaptive Testing