1. Ciprian M. Crainiceanu is Assistant Professor, Department of Biostatistics, Johns Hopkins University, Baltimore, MD 21205 . Peter J. Diggle is Professor, Department of Medicine, Lancaster University, Lancaster LA1 4YF, U.K. and Adjunct Professor, Department of Biostatistics, Johns Hopkins University, Baltimore, MD 21205 . Barry Rowlingson is Research Officer, Department of Mathematics and Statistics, Lancaster University, Lancaster LA1 4YF, U.K. . This work was supported byWorld Health Organization...