Hi there,

 

I have a question about one command sentence when I follow the example
in the book of "Survival analysis in S":

 

 > aml1<-aml[aml$group==1]

 

but I got the error warning: NULL data frame with 23 rows

 

Thus, I couldn't keep going on the next command:

 

esf.fit<-survfit(Surv(aml1,status)~1).

 

and also when I try 

 

> aml1<-aml[aml$group==1,]

> aml1

 

I got 

 

[1] time   status x     

<0 rows> (or 0-length row.names)

 

 

Could you please help me with these questions? I'm stuck here. Thank you
very much!

 

Cheers,

Linda


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