SIMULATION STUDY OF A NEW EQUATING METHOD IN THE LATENT TRAIT MODEL

Abstract

An equating method of two scales based upon two separate tests using common subjects was proposed in the previous paper(Noguchi, 1983). In that method, each subject's scale values are estimated on the two separate scales, and then the principal component for the whole group of examinees is extracted, which corresponds to the equating equation. In this paper, using computer simulation, the validity of Noguchi's method is examined in various situations, changing the difficulty levels of the two tests, the distribution of subjects and the number of subjects. As a consequence, Noguchi's equating method proved to be valid in situations where the two tests are not so different in difficulty levels and the subjects'ability distributes for a wide range.