From single-case studies to practice-based knowledge: aggregating and synthesizing case studies.

Recent developments in case study methodology reflect a rising interest that clinicians and researchers share in building a clinically useful and empirically sound knowledge base from single-case studies. The present article describes three types of single-case studies (clinical, experimental, systematic) and examines their potential contributions to psychotherapy research. It then lays out three ways in which single-case studies can be aggregated and synthesized to enhance clinical understanding: (a) a case database that allows clinicians to efficiently search for relevant cases, (b) a metasynthesis of single-case studies that integrates common themes across similar cases, and (c) an individual case comparison method in which closely matched cases are compared to identify both therapeutic and hindering processes.