[R] Question about survival::survfit

[Marc Schwartz]

> On Aug 5, 2015, at 9:25 AM, Evan Kransdorf <evan.kransdorf at gmail.com> wrote:
> 
> I am wanting to do a KM curve of two groups using survival. For some
> reason, the summary(survfit) gives me the following output:
> 
> 
> 
>           records n.max n.start events median 0.95LCL 0.95UCL
> 
> VAR=N   10931 10931   10931   1646     NA      NA      NA
> 
> VAR=Y    3452  3452    3452    906     NA      NA      NA
> 
> 
> 
> I am not sure why it won’t give me median survival for each group?  There
> are no NA in my data.
> 
> 
> 
> Thanks very much


Presumably, because the survivorship function never crosses below 0.5. You may need to refresh yourself on the definition of median survival.

Plot the curves to visually confirm.

Regards,

Marc Schwartz