Beyond the Reliable Change Index – Misunderstandings and Myths Surrounding the Jacobson–Truax Method

Abstract: More than three decades after its publication, Jacobson and Truax (1991) remains central to evaluating clinically significant change, yet it is often cited in simplified or partially reconstructed forms that invite misleading interpretations and myths. We approach Jacobson and Truax's (1991) contribution as a landmark that warrants careful preservation and recenter what the Jacobson–Truax (JT) method was intended to mean. We first restate the JT-method as specified by Jacobson and Truax (1991) , emphasizing its two criteria for establishing clinically significant change. We then illustrate recurring patterns in which later publications cite the JT-method in incomplete or misleading ways and discuss why such drift matters for interpretation, comparability, and cumulative progress. Building on the original framework, we appraise boundary conditions and outline extensions that retain the key insights of accounting for measurement error. We conclude with recommendations for transparent reporting when citing Jacobson and Truax (1991) .