Hi, listers
I am experiencing problems obtaining a Kaplan-Meier estimate of the
hazard function. Using -sts graph, haz- returns an error "Variable __ub
not found" r(111). The error does not, however, appear when requesting
the surivival function of the same data. I can reproduce the error using
the leukemia data from stata-press (see printout below), even after a
complete reinstall of Stata 9. How complete it actually was is hard to
tell, my settings were still identical to what they were prior to the
reinstall even though I renamed the old "C:\Program Files\Stata9-folder"
to Stata9_old. Where else does Stata store information?
Until now I have been using -sts gen haz=h- instead, but today, by a one
time fluke, stata suddenly returned different results compared to
earlier. I would normally be willing to write this off as some fault on
my part had it not been for the disturbing fact that the fluke-results
were a lot more in sync with the predictions from my models. The results
are, however, not reproducable in the same session even after doing no
changes to the dataset.
I am now wondering if the two problems are somehow related, and fear
there is something wrong with the hazard-estimates I have been
recieving. Can someone confirm the problem, or suggest a way to handle
it?
Thanks,
-Steinar
. use http://www.stata-press.com/data/r8/leukemia, clear
(Leukemia Remission Study)
. stset weeks, failure(relapse)
failure event: relapse != 0 & relapse < .
obs. time interval: (0, weeks]
exit on or before: failure
------------------------------------------------------------------------
------
42 total obs.
0 exclusions
------------------------------------------------------------------------
------
42 obs. remaining, representing
30 failures in single record/single failure data
541 total analysis time at risk, at risk from t = 0
earliest observed entry t = 0
last observed exit t = 35
. sts graph
failure _d: relapse
analysis time _t: weeks
. sts graph, haz
failure _d: relapse
analysis time _t: weeks
variable __ub not found
r(111);
*
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