Hi, if 50% survival probability horizontal line in a Kaplan-Meier survival curve overlap one of the step line between 2 time points t1 and t2, the survfit() from survival package estimates median survival as t2 (the longest time point). But I saw some articles (page 23: http://www.amstat.org/chapters/northeasternillinois/pastevents/presentations/summer05_Ibrahim_J.pdf) recommend the smallest time t such time S(t)<=0.5. 

What is the convention for the definition of median survival?

Thanks

John

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