Date of Award


Document Type


Degree Name

MA in Psychology



First Advisor

William F Chaplin

Second Advisor

Raymond DiGiuseppe


The structure of the Outcome Questionnaire-45 (OQ-45; Lambert et al., 2004b) was examined across three time points in a sample of 199 psychotherapy clients at an outpatient community clinic in the greater New York area. Five models—a one-factor model, two-factor (oblique) model, three-factor (oblique) model, two sub-factor bifactor model, and three sub-factor bifactor model—were tested at baseline, 8 weeks, and 16 weeks. The two sub-factor bifactor model fit the data best at baseline, and the three sub-factor bifactor model fit the data best at 8 weeks and 16 weeks. These results demonstrate that the OQ-45 items load onto one general distress factor across time. The extent to which the items additionally load onto the Symptom Distress, Interpersonal Relations, and Social Roles subscales of the OQ-45 changes over time.