I would like to start by saying that I am not a SAS user myself.   I have recently received a statistical report based on a data analysis performed in SAS, that includes results from a Kaplan-Meier survival analysis performed using the Lifetest procedure. The analysis included a comparison of survival analysis results for different subsets of subjects. Even though the event of interest occurred in less than half of the subjects in each subset, the report author specified a median survival time and an accompanying 95% confidence interval. For some subsets only the lower bound of the 95% CI was specified but no median and no upper bound. Unfortunately, I have no access to the original SAS output.   Can this be correct? From what I have understood so far about Kaplan-Meier survival analysis, median survival can only be specified if the event of interest has occurred in at least 50% of the subjects that were initially at risk. Is my thinking incorrect?   KR, Frank ... View more