Session evaluation scale: psychometric evaluation and development of short versions.

Area of Science:

• Psychometrics
• Clinical Psychology
• Therapy Outcome Measurement

Background:

• Accurate assessment of psychotherapy session quality is crucial for treatment effectiveness.
• Existing measures may require refinement for optimal clinical utility and brevity.

Purpose of the Study:

• To evaluate the psychometric properties of the five-item patient-rated Session Evaluation Scale (SES-P) and therapist-rated Session Evaluation Scale (SES-T).
• To develop and validate concise three-item versions of both SES-P and SES-T.
• To assess the reliability and validity of these scales in adult psychotherapy samples.

Main Methods:

• Utilized two independent samples of adult psychotherapy patients (N=1,043) and therapists (N=151).
• Employed item response theory analysis for scale shortening and psychometric evaluation.
• Conducted confirmatory factor analysis (CFA) and multigroup CFA to assess structure and invariance.
• Assessed reliability (internal consistency) and validity, including measurement invariance across session formats.

Main Results:

• The five-item SES-P and SES-T exhibited excellent internal reliability (omega total ≥ .80) and a clear unidimensional structure (CFI ≥ .95).
• Full measurement invariance was confirmed for the patient-form across in-person and video-based sessions.
• The three-item versions maintained sound psychometric properties (CFI ≥ .95; omega total > .75) with strong agreement with the five-item versions.

Conclusions:

• The patient- and therapist-rated Session Evaluation Scales (SES-P and SES-T) are reliable and psychometrically robust.
• The ultra-short, three-item versions provide a valid and efficient means for nuanced session quality evaluation.
• These scales are valuable tools for assessing and improving psychotherapy outcomes.