"...Are Humanistic Psychotherapies Efficacious?
Quantitative Humanistic Psychotherapy Research
Quantitative outcome research is the most positivistic of the different threads of HP research, and has generally been undertaken as political necessity. Since the founding of Psychotherapy Research, research on the outcome of humanistic psychotherapies has increased many times over, from 37 studies, reviewed by Greenberg, Elliott & Lietaer (1994) in the first meta-analysis of this literature, to many more than the 191 studies included in the most recent meta-analysis (Elliott et al., 2013). These meta-analyses consistently and with increasing strength and differentiation support the following conclusions: