Brennan (Brennan, R. L., 2012) noted that users of test scores often want (indeed, demand) that subscores be reported, along with total test scores, for diagnostic purposes. Haberman (Haberman, S. J., 2008) suggested a method based on classical test theory (CTT) to determine if subscores have added value over the total score. According to this…

There is an increasing interest in reporting subscores, both at examinee level and at aggregate levels. However, it is important to ensure reasonable subscore performance in terms of high reliability and validity to minimize incorrect instructional and remediation decisions. This article employs a statistical measure based on classical test theory…