ABSTRACT
For well over 75 years research has been conducted into the effectiveness of psychotherapy. Initial ®ndings in the early years suggested that psychotherapy is effective, and that `common factors' are more important in the process of change than techniques or strategies speci®c to any orientation. As early as 1936 Rosenzweig ®rst talked of the `implicit common factors' spanning different methods of psychotherapy which he listed as: the personality of the therapist, providing clients with an alternative way of looking at things, and the emphasis that although orientations may differ in focus, they all achieve change in their particular ways. In 1975 Luborsky et al. undertook a metaanalytic study of more than a hundred research projects that had been conducted between 1949 and 1974, all aimed at showing that one particular approach was superior to another in the treatment of speci®c conditions. After careful analysis, they found that there was no signi®cant difference between the effectiveness of various therapies for speci®c conditions; that people who go through the different therapies that have been researched all appear to show improvement. They concluded that `we can reach a ``Dodo bird verdict'' ± it is usually true that everyone has won and all must have prizes' (Luborsky et al., 1975: 1003). Smith and Glass (1977) con®rmed the `Dodo bird verdict' in a further meta-analytic study, suggesting that although much writing and research was going into attempting to prove differential outcomes between approaches, the overwhelming ®nding suggested that all types of therapy, when competently used, may be regarded as equally effective. Despite these ®ndings, researchers continued in the endeavour to establish differential effectiveness between therapies.
