1 Department of Biostatistics, University of Liverpool, Liverpool, UK
2 Centre for Statistics in Medicine, University of Oxford, Oxford, UK
3 School of Social and Community Medicine, University of Bristol, Bristol, UK and Division of Surgery, Head & Neck, University Hospitals NHS Foundation Trust, Bristol, UK
4 Northern Ireland Network for Trials Methodology Research, Queen's University Belfast, Belfast, UK
5 Center for Medical Technology Policy, Baltimore, Maryland, USA