• Outcome research in a group therapy program was conducted with therapists in training who had little prior experience with group therapy. Significantly greater improvement over an initial three-month period was found for treated patients when compared with control patients on a multivariate combination of five outcome criteria. Some, but not all, of the five separate criteria indicated such a difference. Only slight, nondifferentiating improvement was found for target symptoms. significantly greater improvement over the three-month period on the multivariate combination was also found for treated patients who had begun therapy during the second year of the program when compared with treated patients who had begun therapy during the first year of the program. Finally, significant improvement over the three-month period on the multivariate combination was found for both treated and control patients.
Piper WE, Debbane EG, Garant J. An Outcome Study of Group Therapy. Arch Gen Psychiatry. 1977;34(9):1027-1032. doi:10.1001/archpsyc.1977.01770210041003