Clinical assessment involves collecting information to determine how and why a person is behaving abnormally and how they can be helped. Clinicians use clinical interviews, tests, and observations as assessment tools, which must be standardized, reliable, and valid. The DSM-IV-TR is commonly used for diagnosis and describes diagnostic criteria across five axes. Treatment decisions are informed by assessment and diagnosis, with the goal of empirically supported and evidence-based interventions. Research shows that therapy is generally more effective than no treatment, and that specific therapies can effectively treat particular disorders.