[R] The survival rate at a certain time

[Austin, Matt]

You can use the summary method for a survfit object from the package
survival as in the following example:

> library(survival)
> summary( survfit( Surv(futime, fustat)~rx,data=ovarian), times=500)
Call: survfit(formula = Surv(futime, fustat) ~ rx, data = ovarian)

                rx=1 
        time       n.risk      n.event     survival      std.err lower 95%
CI 
     500.000        5.000        6.000        0.538        0.138
0.326 
upper 95% CI 
       0.891 

                rx=2 
        time       n.risk      n.event     survival      std.err lower 95%
CI 
     500.000        7.000        4.000        0.658        0.141
0.433 
upper 95% CI 
       1.000 


Matt Austin
Statistician

Amgen 
One Amgen Center Drive
M/S 24-2-C
Thousand Oaks CA 93021
(805) 447 - 7431


> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch
> [mailto:r-help-bounces at stat.math.ethz.ch]On Behalf Of Lisa Wang
> Sent: Monday, December 06, 2004 8:27 AM
> To: R-Help
> Subject: [R] The survival rate at a certain time
> 
> 
> Hello there,
> 
> I am doing analysis on survival data. How do I pick out a 
> probability of
> survival at a chosen landmark time(for example, 3 years, 4 years) from
> the result of "survfit"? or any other functions? As I know, the result
> of 'survfit' only have the probabilities for all event or cencor time.
> 
> Thank you very much
> 
> Lisa Wang
> 
> Princess Margaret Hospital
> Toronto, Ca
> 
> tel: 416-946-4501 ext.5201
> 
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