Using Stata version 13.1 on Windows 7 I am still battling with Kaplan Meier survival curves. I am performing the same analysis separately on three groups of data. For two of the groups I get the outcome I expect and the data has been censored at 30 days.
For one group however, the last observed exit t = 286. I expected this to be 30
Please could someone suggest possible reasons why the data has not been censored at 30 days?
Thank you
Claire
Code:
stset lengthofadmission, fail(Outcome) exit(lengthofadmission==30)
failure event: Outcome != 0 & Outcome < .
obs. time interval: (0, lengthofadmission]
exit on or before: lengthofadmission==30
------------------------------------------------------------------------------
650 total observations
268 event time missing (lengthofadmission>=.) PROBABLE ERROR
6 observations end on or before enter()
------------------------------------------------------------------------------
376 observations remaining, representing
170 failures in single-record/single-failure data
7819 total analysis time at risk and under observation
at risk from t = 0
earliest observed entry t = 0
last observed exit t = 30
Code:
stset lengthofadmission, fail(Outcome) exit(lengthofadmission==30)
failure event: Outcome != 0 & Outcome < .
obs. time interval: (0, lengthofadmission]
exit on or before: lengthofadmission==30
------------------------------------------------------------------------------
339 total observations
113 event time missing (lengthofadmission>=.) PROBABLE ERROR
8 observations end on or before enter()
------------------------------------------------------------------------------
218 observations remaining, representing
29 failures in single-record/single-failure data
8642 total analysis time at risk and under observation
at risk from t = 0
earliest observed entry t = 0
last observed exit t = 286
Thank you
Claire