Hi, I would like to know how to handle truncated data. My intend is to have the survival curve of a software fault in order to have some information about fault lifespan. I have some observations of a software system between 2004 and 2010. The system was first released in 1994. The event considered is the disappearance of a software fault. The faults can have been introduced at any time, between 1994 and 2010. But for fault introduced before 2004, there is not mean to know their age. I used the Surv and survfit functions with type interval2. For the faults that are first observed in 2004, I set the lower bound to the lifespan observed between 2004 and 2010. How could I set the upper bound ? Using 1994 as a starting point to not seems to be meaningful. Neither is using only the lower bound. Should I consider another survival estimator ? Thanks in advance. -- Nicolas Palix Tel: +33 4 76 51 46 27 http://membres-liglab.imag.fr/palix/