[R] how to code the censor variable for "survfit"
klaster at karlin.mff.cuni.cz
Sun Apr 29 06:51:40 CEST 2007
And be careful - R is case-sensitive. You have "surv(...)" instead of
"Surv(...)" in your code, that will probably give an error.
The coding is as you have it - 1=failure, 0=censored.
Christos Hatzis napsal(a):
> The Surv object contains the information on the type of censoring.
> Look at ?Surv
> for an explanation of how censored events are represented.
>> -----Original Message-----
>> From: r-help-bounces at stat.math.ethz.ch
>> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Lu, Jiang
>> Sent: Saturday, April 28, 2007 11:10 PM
>> To: r-help at stat.math.ethz.ch
>> Subject: [R] how to code the censor variable for "survfit"
>> Dear r-helpers,
>> This is my first time to run survival analysis. Currently, I
>> have a data set which contains two variables, the variable of
>> time to event (or time to censoring) and the variable of
>> censor indicator. For the indicator variable, it was coded as
>> 0 and 1. 0 represents right censor, 1 means event of
>> interest. Now I try to use "survfit" in the package of
>> "survival". I wrote the following code:
>>> rptsurv <- survfit(surv(time,censor)~1,data=x)
>> Before I run the code, I am concerned with my 0/1 coding to
>> the censor indicator because I did not see any argument in
>> the syntax of "survfit", which may tell the program that
>> value 1 means event. I checked the documentations and R-help
>> archive, but ended in vain.
>> Would you please kindly tell me how "survfit" treats censor variables?
>> In 0/1 coding, is it the default that 1 means event and 0
>> means right censor? What if the censor was coded as 2 or 3
>> instead of 0 or 1? I means how the "survfit" knows the
>> difference. In SAS, if a "lifetest"
>> procedure (similar to survfit) is performed, there is an
>> argument specifying which value in the censor variable is
>> treated as event.
>> I know I could just compare the results from R and from SAS
>> to see the difference. However, I really want to know exactly
>> how "survfit" deals with this problem. Thank you very much in advance.
>> Jiang Lu
>> University of Pittsburgh
>> R-help at stat.math.ethz.ch mailing list
>> PLEASE do read the posting guide
>> and provide commented, minimal, self-contained, reproducible code.
> R-help at stat.math.ethz.ch mailing list
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
Dept. of Probability and Statistics
Charles University in Prague
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