[Descriptive single case analyses--a strategy for studying effectiveness correlations in psychotherapy]

A method of data analysis based on single case studies is investigated. It is intended to lead to empirically grounded hypotheses about the differences in effects of various therapeutic methods. The data bases are 16 documented therapies, eight of which are client-centered therapies and interactional behavior therapies respectively. Descriptive single case analyses were carried out in four steps: 1. documentation of single cases; 2. description of individual patterns of therapeutic effects; 3. comparisons within treatment groups; 4. comparisons between treatment groups. Results show that individual differences within groups exceed similarities, so that there is little evidence of a strong influence of the treatment method on individual patterns of therapeutic effects. This result leads to the conclusion that a typology of therapeutic processes should be based on more factors than the treatment method alone.