Process assessment in treatment matching research.

A complete understanding of the effects of treatment requires an examination of the process by which the treatment produces the outcome as well as a thorough assessment of the outcomes. Process assessment assumes even greater importance in matching research than in other types of treatment research, since client-treatment interactions are hypothesized to be moderated or mediated by specific treatment components. The role of process assessment in treatment matching research is examined using Project MATCH as an illustrative example. Four process domains, including dose of treatment, within-session treatment activities, the therapeutic alliance and extra-session activities, are described in terms of their role as mediators or moderators of treatment outcome and the perspectives by which they are assessed in Project MATCH.