Dear r-users, I have longitudinal data with measures and a binary trait (status) made on hundreds of people every 3 years during nine years. I tried different models but I wonder if it is possible to use survival analysis. If I take Surv(time, status), I have hundreds of ties and I am not sure it is a nice case to do survival analysis. I wonder if I could take Surv(age, status) in a cox model with coxph() or a logrank test for a genotype factor with survdiff() since people enter the study at different ages which implies different survival time and thus very few ties. Actually I can't find similar examples in documentation. Thanks in advance. jacques ------------------------------------------------------------------- Jacques VESLOT CNRS UMR 8090 I.B.L (2?me ?tage) 1 rue du Professeur Calmette B.P. 245 59019 Lille Cedex Tel : 33 (0)3.20.87.10.44 Fax : 33 (0)3.20.87.10.31 http://www-good.ibl.fr