Social and Behavioral Sciences Commons^™

Dose-Effect Relationship In Routine Outpatient Psychotherapy: Does Treatment Duration Matter?, Niklaus Stulz, Wolfgang Lutz, Stephen Mark Kopta, Takuya Minami, Stephen M. Saunders

Psychology Faculty Research and Publications

Objective: There is an ongoing debate concerning how outcome variables change during the course of psychotherapy. We compared the dose–effect model, which posits diminishing effects of additional sessions in later treatment phases, against a model that assumes a linear and steady treatment progress through termination. Method: Session-by-session outcome data of 6,375 outpatients were analyzed, and participants were categorized according to treatment length. Linear and log-linear (i.e., negatively accelerating) latent growth curve models (LGCMs) were estimated and compared for different treatment length categories. Results: When comparing the fit of the various models, the log-linear LGCMs assuming negatively accelerating treatment progress consistently …