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st: AW: Person-period dataset, stcox, subjects in analysis


From   "Martin Weiss" <martin.weiss1@gmx.de>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: AW: Person-period dataset, stcox, subjects in analysis
Date   Mon, 18 May 2009 09:07:11 +0200

<> 

You could also use -estat summ-. -keep-ing as recommended by Jeph tells
Stata to drop every subject not used in the estimation which is a rather
harsh step...


*************
webuse kva, clear
stset failtime
stcox load bearings
estat summ
*************



HTH
Martin

-----Ursprüngliche Nachricht-----
Von: owner-statalist@hsphsun2.harvard.edu
[mailto:owner-statalist@hsphsun2.harvard.edu] Im Auftrag von MAY BAYDOUN
Gesendet: Montag, 18. Mai 2009 01:33
An: statalist@hsphsun2.harvard.edu
Betreff: st: Person-period dataset, stcox, subjects in analysis

Dear Statalisters,

This may be a straightforward question with an obvious answer, but I need
your help on it. I have a person-period dataset and I used stset command
specifying origin and id as well as failure and exit. This gave me a
specific number of failures and number of subjects at risk. I ran stcox
using a variable that has missing values for a number of those subjects. I
am trying obtain a selection variable so I can look at baseline
characteristics of those subjects that were selected for this analysis. 
Which of the variables that were generated through the stset command should
I be using for this purpose? 


 stcox x

         failure _d:  failuredem == 2
   analysis time _t:  (age50dem-origin)
             origin:  time origin==1
  enter on or after:  time origin2==1
  exit on or before:  failuredem==1
                 id:  id

Iteration 0:   log likelihood = -1697.8111
Iteration 1:   log likelihood = -1696.3502
Iteration 2:   log likelihood = -1696.3477
Refining estimates:
Iteration 0:   log likelihood = -1696.3477

Cox regression -- Breslow method for ties

No. of subjects =      2321                     Number of obs   =     15721
No. of failures =      270
Time at risk    =  52641.86847
                                                   LR chi2(1)      =
2.93
Log likelihood  =   -1696.3477                     Prob > chi2     =
0.0871

----------------------------------------------------------------------------
--
          _t | Haz. Ratio   Std. Err.      z    P>|z|     [95% Conf.
Interval]
-------------+--------------------------------------------------------------
--
         x|   1.247601    .159471     1.73   0.084     .9711212   1.602796
----------------------------------------------------------------------------
--

So, basically, I want to be able to describe the 2,321 subjects in that
analysis. I did that before, but I can't remember how anymore. Thanks for
any help you can provide,


Sincerely,

May







      
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