David Francis1
, Ian Roberts2
, Diana R Elbourne3
, Haleema Shakur2
, Rosemary C Knight3
, Jo Garcia3
, Claire Snowdon3,4
, Vikki A Entwistle5
, Alison M McDonald5
, Adrian M Grant5
and Marion K Campbell5 
1Centre for Research and Innovation Management, Brighton, UK
2Nutrition and Public Health Interventions Research Unit, London School of Hygiene and Tropical Medicine, Keppel Street, London, UK
3Medical Statistics Unit, London School of Hygiene and Tropical Medicine, Keppel Street, London, UK
4Centre for Family Research, University of Cambridge, Free School Lane, Cambridge, CB2 3RF, UK
5Health Services Research Unit, University of Aberdeen, Health Sciences Building, Foresterhill, Aberdeen, UK