Subscore Equating and Profile Reporting

ABSTRACT The purpose of this study is to address the necessity of subscore equating and to evaluate the performance of various equating methods for subtests. Assuming the random groups design and number-correct scoring, this paper analyzed real data and simulated data with four study factors including test dimensionality, subtest length, form difference in difficulty, and sample size. The results indicated that reporting subscores without equating provides misleading information in terms of score profiles and that reporting subscores without a pre-specified test specification brings practical issues such as constructing alternate subtest forms with comparable difficulty, conducting equating between forms with different lengths, and deciding an appropriate score scale to be reported.