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In the first section a controlled treatment study of male sexual dysfunction is described. 'Unlucky' randomization of subjects yielded treatment groups which differed with respect to variables of possible prognostic significance. Hence the results are largely uninterpretable. In the second section the predominantly negative or inconsistent findings in sex therapy outcome research are reviewed and methodological problems, such as those described in the first part, are considered as possible reasons for these negative findings. The interrelationships are explored between small treatment groups, prognostic variability, bias, power, and small expected treatment effects. A strategy for future research is proposed, with particular emphasis on the recognition and use of relevant prognostic indices.


Journal article


Psychol Med

Publication Date





851 - 863


Combined Modality Therapy, Erectile Dysfunction, Follow-Up Studies, Humans, Male, Marital Therapy, Sexual Behavior, Testosterone