1. University of Oxford; Department of Social Policy and Intervention; Barnett House 32 Wellington Square Oxford UK OX1 2ER
2. Cochrane; Cochrane Response; St Albans House 57-59 Haymarket London UK SW1Y 4QX
3. Norwegian Institute of Public Health; Division of Health Services; PO box 222 Skøyen 0213 Oslo Norway
4. University of Plymouth; Centre for Mathematical Sciences, School of Engineering, Computing and Mathematics; Plymouth UK
5. Coventry University; Centre for Innovative Research Across the Life Course (CIRAL); Richard Crossman Building Gosford Street Coventry UK CV1 5FB