Clinically significant and practical! Enhancing precision does make a difference. Reply to McGlinchey and Jacobson,...

Area of Science:

• Psychology
• Clinical Psychology
• Psychotherapy Research

Background:

• Assessing reliable and clinically significant change is crucial in psychotherapy research.
• Previous studies by Jacobson and Truax, and McGlinchey and Jacobson, suggested minimal differences between traditional and refined methods.
• A re-analysis identified a critical error in the standard error of measurement used in prior calculations.

Purpose of the Study:

• To re-evaluate the Jacobson and Truax data using both traditional and refined methods for assessing change.
• To address discrepancies in findings regarding the practical utility of different statistical approaches.
• To highlight the theoretical and practical advantages of a refined method for analyzing clinical significance.

Main Methods:

• Secondary analysis of existing psychotherapy data (Jacobson and Truax).
• Comparison of a traditional statistical approach with a refined method for determining reliable and clinically significant change.
• Correction of a previously used standard error of measurement value.

Main Results:

• A calculation error in prior work led to the erroneous conclusion that methods yielded similar results.
• Re-analysis with the correct standard error of measurement revealed significant differences in client change classifications between the two methods.
• The refined method demonstrated superior precision and better distinction between individual and group-level analyses.

Conclusions:

• The refined method offers significant theoretical and practical advantages over the traditional approach.
• The refined method is practically manageable, with calculations taking approximately 30 minutes.
• The study provides an SPSS setup for researchers to implement the refined method, facilitating its adoption and improving comparability across studies.