1. MRC Biostatistics UnitUniversity of Cambridge Cambridge UK
2. Department of Public Health and Primary CareUniversity of Cambridge Cambridge UK
3. École Nationale de la Statistique et de l'Administration Économique Malakoff France
4. School of Social and Community MedicineUniversity of Bristol Bristol UK
5. Department of Preventive MedicineUniversity of Mississippi Medical Center Jackson Mississippi
6. Center of Biostatistics and BioinformaticsUniversity of Mississippi Medical Center Jackson Mississippi