Hi,

I am trying to generate a Kaplan Meier graph using my data set looking at recurrence after a surgery (with or without steroid administration). I just want to generate two KM curves showing the failure curve of those where steroids were given and those where they were not.

My variables are the following:
steroids (steroids administered) = 1 or 0
txfail (treatment failure)=1 or 0
duration = months to failure

I get multiple errors when I use the command: stset duration, id(steroid) failure(txfail) and the graph is correspondly incorrect. Can anyone advise?

stset duration, id(steroid) failure(txfail)

id: steroid
failure event: txfail != 0 & txfail < .
obs. time interval: (duration[_n-1], duration]
exit on or before: failure

------------------------------------------------------------------------------
93 total observations
62 event time missing (duration>=.) PROBABLE ERROR
17 multiple records at same instant PROBABLE ERROR
(duration[_n-1]==duration)
12 observations begin on or after (first) failure
------------------------------------------------------------------------------
2 observations remaining, representing
2 subjects
2 failures in single-failure-per-subject data
6 total analysis time at risk and under observation
at risk from t = 0
earliest observed entry t = 0
last observed exit t = 4