Constructing validity arguments for test combinations

•An extension of the argument-based approach to validation.•Approach to validating combinations of tests that lead to one decision.•An interpretive argument is transformed to fit test combinations.•Validity arguments mainly address claims specific for test combinations.•Approach fosters an in-depth evaluation of the assessment program.

The argument-based approach to validation has been widely adopted in validation theory. However, this approach aims to validate the intended interpretation and use of a single test or assessment. This article proposes an extension of the argument-based approach for validation of multiple tests. This extension is illustrated with the validation of a competency assessment program (CAP). This CAP was validated in collaboration with a quality manager of an educational program. In this case study, it became apparent that this approach fosters an in-depth evaluation of the assessment program and that the approach appears suitable for validation efforts of competency assessment programs. The approach guides validation research from a more general perspective, but also guides more detailed validation efforts.