Influence of social support on success of therapeutic interventions: A meta-analytic review. 
Researchers view social support as an important extratherapeutic factor in the field of psychotherapeutic research.  In an effort to verify the accuracy of this view, and to determine the degree to which social support influences the outcome of psychotherapeutic interventions, the authors conducted an exhaustive review of studies published until 2007.  This search yielded 27 studies, including 29 independent samples that composed a meta-analysis.  The results demonstrated a small mean correlation of r = .13 between social support and psychotherapy outcome on an almost homogeneous data set.  Different operationalizations of social support and forms of interventions did not result in different effect sizes on a statistically significant level. ( PsycINFO Database Record (c) 2010 APA, all rights reserved).