Listening to Prozac but Hearing Placebo: A Meta-Analysis of Antidepressant Medication

Authors: Kirsch, I., Sapirstein, G.
"Examination of pre–post effect sizes among depressed individuals assigned to no-treatment or wait-list control groups suggest that approximately one quarter of the drug response is due to the administration of an active medication, one half is a placebo effect, and the remaining quarter is due to other nonspecific factors."