The Unfolding Case Formulation: The Interplay of Description and Inference

Single subject research (SSR) can complement findings from aggregated group data and contribute uniquely toward the goal of generating and generalizing scientific knowledge in psychology. The present study illustrates these assertions with psychotherapy case formulation research. In earlier work my team and I identified and operationalized multiple dimensions of quality in case formulations. These include comprehensiveness, formulation elaboration, precision of language, complexity, coherence, treatment plan elaboration, goodness-of-fit between the treatment plan and the rest of the case formulation, and systematic process in following an a priori conceptual scheme. Using these dimensions, we found that cognitive-behavioral and psychodynamic experts generated higher quality case formulations than novice and experienced therapists. Experts also generated more ideas in their formulations and reasoned more inductively than deductively. In the present study, we explore these results further by qualitatively examining the highest quality psychodynamic and cognitive-behavioral formulations on the most difficult patient material, and then compare these two formulations with the two falling nearest to the 25th percentile range in quality ratings. Our goals were to investigate expert reasoning processes in case formulation more closely and to illustrate how aggregated group data and single subject research can mutually inform each other. We close by suggesting characteristics of a practical measure of case formulation expertise that may facilitate further investigations.