Affiliation: | A1 Department of Epidemiology Research, Danish Epidemiology Science Centre, Statens Serum Institut, Artillerivej 5, DK 2300 Copenhagen S, Denmark E-mail: pes@ssi.dk A2 Department of Biostatistics, University of Copenhagen, Blegdamsvej 3, DK 2000 Copenhagen D, Denmark E-mail: pka@biostat.ku.dk |