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st: RE: Re: Bug in StataIC/10.1


From   "Kieran McCaul" <Kieran.McCaul@uwa.edu.au>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: Re: Bug in StataIC/10.1
Date   Fri, 23 Oct 2009 06:00:29 +0800

...

Check your survival time variable.  In the current data, the last record
has a survival time of 4.112e+15.

. use "C:\data\Data_that_reveals_bug.dta", clear

. summ

    Variable |       Obs        Mean    Std. Dev.       Min        Max
-------------+--------------------------------------------------------
           x |       200   -.2138703    1.850259  -22.16818    .760034
         _st |       200           1           0          1          1
          _d |       200           1           0          1          1
          _t |       200    2.06e+13    2.91e+14   .1891971   4.11e+15
         _t0 |       200           0           0          0          0

. gsort -_t

. list in 1/5

     +----------------------------------------+
     |         x   _st   _d          _t   _t0 |
     |----------------------------------------|
  1. | -22.16818     1    1   4.112e+15     0 |
  2. |  -5.32375     1    1   8350.7305     0 |
  3. | -2.870201     1    1   4820.9951     0 |
  4. | -3.992061     1    1   4177.3936     0 |
  5. | -2.601513     1    1   2968.2688     0 |
     +----------------------------------------+

. drop if _t>9000
(1 observation deleted)

. summ x

    Variable |       Obs        Mean    Std. Dev.       Min        Max
-------------+--------------------------------------------------------
           x |       199   -.1035472    .9971032   -5.32375    .760034

. stcox x

         failure _d:  __00000A
   analysis time _t:  __000009

Iteration 0:   log likelihood = -857.93367
Iteration 1:   log likelihood = -784.89106
Iteration 2:   log likelihood = -765.14913
Iteration 3:   log likelihood = -763.48685
Iteration 4:   log likelihood = -763.47248
Iteration 5:   log likelihood = -763.47248
Refining estimates:
Iteration 0:   log likelihood = -763.47248

Cox regression -- no ties

No. of subjects =          199                     Number of obs   =
199
No. of failures =          199
Time at risk    =  44806.47605
                                                   LR chi2(1)      =
188.92
Log likelihood  =   -763.47248                     Prob > chi2     =
0.0000

------------------------------------------------------------------------
------
          _t | Haz. Ratio   Std. Err.      z    P>|z|     [95% Conf.
Interval]
-------------+----------------------------------------------------------
------
           x |   4.641445   .6697665    10.64   0.000     3.498032
6.15861
------------------------------------------------------------------------
------


______________________________________________
Kieran McCaul MPH PhD
WA Centre for Health & Ageing (M573)
University of Western Australia
Level 6, Ainslie House
48 Murray St
Perth 6000
Phone: (08) 9224-2701
Fax: (08) 9224 8009
email: Kieran.McCaul@uwa.edu.au
http://myprofile.cos.com/mccaul 
http://www.researcherid.com/rid/B-8751-2008
______________________________________________
If you live to be one hundred, you've got it made.
Very few people die past that age - George Burns

-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu
[mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Babak Oskooei
Sent: Thursday, 22 October 2009 10:47 PM
To: statalist@hsphsun2.harvard.edu
Subject: st: Re: Bug in StataIC/10.1

Dear all, 

Re: Bug in StataIC/10.1

There seems to be a bug in Stata 10. I attached the dataset that I used
to fir a Cox PH model. It is simply a survival-time dataset which has
already been stset. The covariate is x and I try to fit a univariate Cox
PH model with x as the sole covariate. So I typed:

stcox x

But Stata 10 gives me an error massage as:

"flat region resulting in a missing likelihood"

Please brear in mind that I can perform the same analysis in Stata 9
without any problem. I would be grateful if someone can give me a clue
on what is causing this error massege in Stata 10 but NOT in Stata 9.

Looking forward to hearing from you.

Babak Oskooei
MRC Clinical Trials Unit
London


      


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