Session evaluation scale: psychometric evaluation and development of short versions

To test the psychometric properties of the five-item patient-rated Session Evaluation Scale (SES-P) (Study 1) and to create a three-item version (Study 2), and to test the psychometric properties of the five-item (Study 3) and three-item (Study 4) therapist-rated version (SES-T).

Two independent samples of adult psychotherapy patients (N  =  1,043) and therapists (N  =  151) completed their respective versions of the SES along with other measures. Psychometric evaluation involved descriptive item analysis, item response theory analysis, confirmatory factor analysis (CFA), and multigroup CFA. Reliability and validity were also assessed. Psychometric scale shortening employed item response theory analysis.

The patient- and therapist-forms of the five-item SES demonstrated strong psychometric properties, including excellent internal reliability (omega total ≥ .80), a clear unidimensional structure (CFI ≥ .95), and full measurement invariance across in-person and video-based session formats (tested only for the patient-form). The three-item versions retain sound psychometric properties (CFI ≥ .95; omega total > .75) and their scores demonstrated strong agreement and minimal bias with the five-item SES scores (Bland-Altman regression average discrepancy ranged from 0.227 to 0.282 points).

The SES-P and SES-T, especially in their ultra-short form, are reliable and psychometrically robust instruments for nuanced evaluation of session quality.