What does validity measure in testing?

Validity in testing is fundamentally about the extent to which a test accurately measures what it is supposed to measure. When a test has high validity, it means that the inferences drawn from the test scores are justified and reliable regarding the intended construct. For instance, if a music therapy assessment claims to measure a client's musical ability, high validity would mean that the test effectively assesses that specific capability rather than unrelated factors.

Furthermore, establishing validity involves various forms, such as content validity, criterion-related validity, and construct validity, each addressing different aspects of how well the test aligns with the defined concept or trait it aims to assess. This focus on alignment with the intended measure is what distinguishes validity from other measurement characteristics, such as reliability or accuracy in the scoring process.

Understanding validity is crucial for music therapists, as it ensures that the assessments and interventions they use to evaluate clients or determine treatment effectiveness are truly reflecting the clients' needs and progress.