Reliable Change and the Reliable Change Index in the context of evidence-based practice: A tutorial review
Background: The concept of Reliable Change in the context of psychological treatment was introduced by Jacobson and colleagues in 1984. Their Reliable Change Index (RCI) specifies the amount of change a client must show on a specific psychometric instrument between measurement occasions for that change to be reliable, i.e., larger than that reasonably expected due to measurement error alone. Only if change is reliable is it then meaningful to consider if it is practically or clinically significant. Evidence of reliable change is, therefore, at the heart of evidence-based practice. Despite this, reliable change and the RCI is rarely considered either in applied/clinical research or practice.Aims: This talk will review the psychometric foundations of the RCI and relate this to clinical/applied/practical significance. Main contributions:In addition to showing how the RCI is calculated for any particular psychological measure I will also demonstrate a graphical procedure that practitioners can use to systematically track, client by client, if they are producing reliable change. I will also show how this can be extended to show if the change is clinically significant. Modifications of the RCI for neuropsychological testing to take account of practice effects will also be discussed. Conclusions: The paper will review the concept of Reliable Change and provide a tutorial in its use and interpretation for researchers and practitioners.