Robert Emery, Professor of Psychology at the University of Virgina, is pre-eminent in the mediation community for having conducted THE longitudinal study about the positive effects of mediation.
This article, published in the New York Times, is essential reading for all divorcing couples.
http://www.nytimes.com/2014/09/07/opinion/sunday/how-divorced-parents-lost-their-rights.html?_r=0