I am working with S+4 under Windows NT4 and I have been having problems with
Surv.
According to the help:
--------------
USAGE
Surv(time, event)
or
Surv(time, time2, event, type=<<see below>>, origin=0)
-----
Surv can be called in two different ways. However, when called in the first way,
-----------------
S+>Surv(avb$V7,event=avb$c=="N")
Error in Surv: Argument "time2" is missing, with no default: Surv(avb$V7,
event = avb$c ==
"N")
Dumped
----------
it does not work. The error originates in the following section of the code:
---------
...
else if(type == "right" || type == "left") {
if(!is.numeric(time))
stop("Time variable is not numeric")
else if(any(time[who] < 0))
stop("Time variable must be >= 0")
if(length(time2) != nn)
stop("Time and status are different lengths")
if(is.logical(time2))
status <- 1 * time2
else if(is.numeric(time2)) {
who2 <- !is.na(time2)
status <- time2 - (max(time2[who2]) - 1)
if(any(status[who2] != 0 & status[who2] != 1))
stop("Invalid status value")
}
else stop("Invalid status value")
ss <- cbind(time, status)
dimnames(ss) <- list(NULL, c("time", "status"))
}
...
-----------------
more specifically at
-----
if(length(time2) != nn)
stop("Time and status are different lengths")
---------
Then, after trying a few different things and to decode the somewhat
cryptical Help, I decided to replace all occurrences of "time2" in the above
code by "event", and, see, it now worked, as expected I guess (at least it
produces the same curves as the deprecated surv.fit).
Is this just a bug? If yes, is my fix OK? In all cases? Or am I missing
something?
BTW, in contrast with the help for survfit and surv.fit I was not able to
obtain confidence intervals for the survival curves in the case of two groups.
Any comment?
L. Molinari
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