[R] how to code the censor variable for "survfit"

[Petr Klasterecky]

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.

Petr


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.
> 
> -Christos 
> 
> 
>> -----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.
>>
>> sincerely,
>>
>> Jiang Lu
>> University of Pittsburgh
>>
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>> PLEASE do read the posting guide 
>> http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>>
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
> 

-- 
Petr Klasterecky
Dept. of Probability and Statistics
Charles University in Prague
Czech Republic