Quantitative Approaches to Treatment Process, Change Process, and Process-Outcome Research

Abstract

To understand how and why psychotherapy works, it is necessary to focus on (both) the process of psychotherapy (i.e., what takes place during the treatment) and the relationship between this process and the outcome of psychotherapy (i.e., the treatment’s clinical effects). In the present chapter, we provide an overview of three main quantitative research strategies that may be differently used to fulfill this aim. These include treatment process research (which investigates what takes place during psychotherapy, regardless of its clinical meaningfulness), change process research (which investigates what takes place during psychotherapy, with regard to its clinical meaningfulness), and process-outcome research (which investigates the relationship between what takes place during psychotherapy and its clinical effects). We first define the process and outcome of psychotherapy; then, for each research approach proposed, we review the research design, data collection, and data analysis issues; finally, we conclude with suggestions for future research.