Establishing Specificity in Psychotherapy Scientifically: Design and Evidence Issues.

Issues related to establishing specificity in psychotherapy are discussed. It is suggested that the null hypothesis that the specific ingredients are responsible for the benefits of psychotherapy should not be rejected unless the evidence is sufficiently inconsistent with the null hypothesis. However, generally or for specific disorders, the uniform efficacy of psychotherapeutic treatments with adults does not provide any evidence that the null hypothesis is false. As well, the relationship of the alliance and outcomes does not provide any evidence against the null and indeed provides evidence for a common-factor model of psychotherapy with adults. Additional evidence that is contrary to a specificity hypothesis is summarized. [ABSTRACT FROM AUTHOR]