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Reliable Change Index: Distributions & Significance Test

Interactive 2D simulator of the Jacobson-Truax Reliable Change Index: view the clinical and normative population densities plus the sampling distribution of the difference score, and see whether a client's improvement is statistically reliable and clinically significant.

Cognitive Science2DModerate60 FPS📱 Mobile-adapted⇄ 3D version

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 2D simulator draws the clinical and normative population densities directly as analytic probability curves on a symptom-severity axis, and — unlike a single spatial snapshot — plots the actual object the Jacobson-Truax test reasons about: the sampling distribution of the difference score itself, with its critical region shaded. Drag the pre/post scores and adjust reliability and population SD to watch both the population picture and the hypothesis test respond live, exactly as a treatment-outcome study would report it.

⚙ Under the hood

A 2D simulator of the Jacobson-Truax Reliable Change Index: analytic probability-density curves for the clinical and normative populations, paired with the sampling distribution of the difference score and its shaded critical region, so you can see exactly why a treatment change is (or isn't) statistically reliable.

clinical psychologypsychotherapy outcomesstatisticsreliable change indexmental healthtreatment evaluationhypothesis testing

2D · HTML5 Canvas 2D · 60 FPS target · runs fully client-side, no install