The validity of subscores for a credentialing test.

Subscores resulting from the administration of high-stakes tests to candidates for credentials in the health professions are desirable for two reasons. First, failing candidates want a profile of performance to plan future remedial studies. Second, training institutions want a profile of performance for their graduates to better evaluate their training. The validity of the interpretation or use of subscores depends on a summative judgment based on a combination of reasoning and empirical analyses, known as validation. We describe this reasoning process and show that with a large credentialing test the validity of any subscore interpretation or use can and should be studied systematically. Validity evidence should be established to support the interpretation and use of subscores that we intend to report. Some principles arise in this study related to the validity of subscores, and some procedures are proposed to help testing program personnel better validate the use of subscores.