[Empirical Conceptualization of Common Factors in Psychotherapy: Factor Structure of the WEB].

Objective: Our goal was to explore the association pattern of 26 common factors and thereby contribute conceptually to the debate on change mechanisms in psychotherapy with an empirically derived conception of superordinate common factors (global common factors). In addition, we tested reliability and validity aspects of a new instrument to assess common factors.

Method: The activation of common factors during in- and outpatient psychotherapy was assessed in 502 patients using a weekly process measure ('Wochenerfahrungsbogen', WEB). The factor structure of the WEB was determined by exploratory factor analysis and verified by confirmatory factor analyses.

Results: The four factors Coping, Therapeutic Alliance, Cognitive Integration, and Affective Processing accounted for 59.8 % of the total variance. Subsequent confirmatory factor analyses, using in- and outpatient samples, confirmed this structure.

Conclusions: The study provided an empirically based integrative categorisation of common factors. Results on reliability (internal consistency) and construct validity indicate that the WEB is an appropriate measurement instrument to investigate global common factors.