Single-case methodology in psychotherapy process and outcome research.

The primary focus of this article is on delineating and explaining the essential characteristics of single-case research methodology applied within the domain of psychotherapy research. Single-case research is presented as a subclass of intrasubject research in which aggregation across Ss is avoided and the generality of one's findings is addressed through replication on a case-by-case basis. The basic ways in which single-case designs vary are also discussed, and 3 basic types of single-case research are differentiated: (a) single-case experiments, (b) single-case quantitative analyses, and (c) case studies. Furthermore, some of the major weaknesses in current single-case psychotherapy research are identified.