Reliable Change Index: Is Treatment Progress Real?

Clinical psychologists don't just ask "did the client's score go down?" — a raw improvement can be nothing more than the natural wobble of a self-report questionnaire. This simulator renders two sampled population clouds on a 3D symptom-severity axis — a dysfunctional (clinical) group and a functional (normative) group — and lets you drag a client's pre- and post-treatment scores across it. Live statistics compute the Jacobson-Truax Reliable Change Index from the measure's test-retest reliability and population standard deviation, and check whether the client's post-treatment score crossed the clinically-significant cutoff into the healthy population's range, exactly as a treatment-outcome study would report it.