Statistical Considerations for Subscore Reporting in Multistage Testing

This study examines factors that influence the reliability of subscores and the accuracy of subscore estimates in multistage testing (MST). The factors considered in the study include the number of subtests, subtest length, correlations among subscores, item pool characteristics such as item pool size relative to the number of items required for an MST and statistical properties of items. Results indicated that the factors that most influenced subscore reliability and subscore estimates were subtest length, item pool size, and the degree of item discrimination.