Evidence of Measurement Invariance in the Working Alliance Inventory Across In-Person and Videoconferencing Psychotherapy.

Objective: The Working Alliance Inventory-Short Revised (WAI-SR) is a self-report measure of therapeutic alliance from the patient's perspective. This study aimed to examine the factor structure of the WAI-SR and evaluate its measurement invariance across in-person and videoconferencing psychotherapy sessions.

Method: The study sample consisted of 1043 adult patients. Exploratory and confirmatory factor analyses were conducted to evaluate the WAI-SR dimensions and structure. Measurement invariance was tested using multi-group confirmatory factor analysis, multiple indicator multiple causes model analysis, and item bias analysis.

Results: The findings supported a three-factor structure of the WAI-SR, encompassing goal, task, and bond dimensions. Results demonstrated configural, metric, scalar, and residual invariance across in-person and videoconferencing formats. The factor structure remained consistent after accounting for patient age and gender. Additionally, no differential item functioning or bias was observed between groups. The WAI-SR exhibited excellent internal consistency and composite reliability.

Conclusions: The WAI-SR is a reliable and valid tool for assessing therapeutic alliance across both in-person and videoconferencing sessions. The equivalence in measurement properties and mean scores across modalities highlights the adaptability of therapeutic alliance to virtual environments, supporting the broader use of telehealth in psychotherapy.