Evaluating the efficacy of psychological therapy

Evaluating the Efficacy of Psychological Therapy In this article, general principles, theoretical backgrounds, methodological issues and possible flaws in planning and conducting efficacy trials of psychological therapies are described. These include sources of variance contributing to improvement of a psychic disorder under psychological therapy (spontaneous remission, regression to the mean, placebo effects, non-specific and specific factors), appropriate control groups, assessment of treatment success with rating scales, study designs, statistical issues and problems of follow-up investigations. The article includes practical suggestions for researchers planning efficacy trials. Ethical problems and critical issues regarding the transfer of the results of controlled trials to practice are also discussed.