To whom may it concern, What is a proper way to analyse a dataset generated from permalgorithm with time varying covariates? It seems like to me that interval censoring would be the choice but Surv suggests that the event would be regarded as occurred at the end of the time interval... Best wishes, Kere Kerenaftali Klein PhD| Biostatistician | Queensland Clinical Trials & Biostatistics Centre The University of Queensland | School of Population Health | Building 33, Level 1| Princess Alexandra Hospital |Ipswich Road | Woolloongabba QLD 4102 | Australia Ph: +61 7 3176 3062| Fax: +61 7 3176 6826 | Email: k.klein at uq.edu.au | Web: http://www.sph.uq.edu.au/qctbc