Authors: Tammy C Hoffmann; Paul P Glasziou; Isabelle Boutron; Ruairidh Milne; Rafael Perera; David Moher; Douglas G Altman; Virginia Barbour; Helen Macdonald; Marie Johnston; Sarah E Lamb; Mary Dixon-Woods; Peter McCulloch; Jeremy C Wyatt; An-Wen Chan; Susan Michie Journal: BMJ Date: 2014-03-07