Erratum to: Evaluating the PRASE patient safety intervention - a multi-centre, cluster trial with a qualitative process evaluation: study protocol for a randomised controlled trial. Issue 1 (December 2016) - Sheard, Laura; O'Hara, Jane; Armitage, Gerry; Wright, John; Cocks, Kim; McEachan, Rosemary; Watt, Ian; Lawton, Rebecca