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RE: st: RE: stset and stsum problem


From   "Kieran McCaul" <kamccaul@meddent.uwa.edu.au>
To   <statalist@hsphsun2.harvard.edu>
Subject   RE: st: RE: stset and stsum problem
Date   Tue, 18 Mar 2008 08:58:20 +0900

I'm still not exactly clear what you've done, but I think that you have
miss-specified the survival time.

If you look at the example data that you provided, for ID=1 there are
two records the first with duration 12 months and the second with
duration 17 months.  Both of these have been calculated by subtracting
firstyearentry from yearexit.  The stset command will therefore
interpret this as a total survival of 29 months for ID=1.

This is not the case, the total survival is only 17 months.

The survival duration should be calculated by subtracting yearentry from
yearexit.

By the "dot in stsum", I assume you mean the missing 50th and 75th
percentiles of the survival distribution.

If the overall survival is better than 50%, then there will be no 50th
or 75th percentile, so they will be missing.



-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu
[mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of
ncdcta00@uniroma2.it
Sent: Monday, 17 March 2008 5:49 PM
To: statalist@hsphsun2.harvard.edu
Subject: Re: st: RE: stset and stsum problem

Dear Kieran,
my problem is that I have dot in stsum when use all observations and  
streg have strange coefficients
thanks a lot


Quoting Kieran McCaul <kamccaul@meddent.uwa.edu.au>:

> What exactly is the problem?
>
> ______________________________________________
> 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) 9224-2140
> Phone: -61-8-9224-2140
> email: kamccaul@meddent.uwa.edu.au
> http://myprofile.cos.com/mccaul
> _______________________________________________
>
> -----Original Message-----
> From: owner-statalist@hsphsun2.harvard.edu
> [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of
> ncdcta00@uniroma2.it
> Sent: Sunday, 16 March 2008 3:44 AM
> To: statalist@hsphsun2.harvard.edu
> Subject: st: stset and stsum problem
>
> Dear statlist,
> I have tried to set my data for a survival analysis, but I have a
> problem when use stset and put all the observations censored.
> My dataset is this:
> id  firstyearentry yearentry    yearexit    duration canvi
> 1      3/2001        3/2001       3/2002       12      0
> 1       3/2001      4/2002          9/2002       17     1
> 2       8/2002       8/2002         11/2002       3     0
> 2       8/2002       12/2002        5/2003        9     0
> 3 .....
> ...
>
> The command that I use is:
> stset dur, f(canvi==1) id(id)
> If I put all the observation censored and not with stsum I have this:
>   stsum;
>
>           failure _d:  canvi
>     analysis time _t:  dur
>                   id:  id
>
>           |               incidence       no. of    |------ Survival
> time -----|
>           | time at risk     rate        subjects        25%       50%
>        75%
>
---------+--------------------------------------------------------------
> -------
>     total |     10661543   .0002694         34301       1025         .
>          .
>
>
> If I  take only the observation with failure ==1 I have this:
>
>      failure _d:  canvi
>     analysis time _t:  dur
>                   id:  id
>
>           |               incidence       no. of    |------ Survival
> time -----|
>           | time at risk     rate        subjects        25%       50%
>        75%
>
---------+--------------------------------------------------------------
> -------
>     total |       960671   .0030687          2951        131       283
>        469
>
> Someone can help me to understand where is the error?
> Thanks in advance.
> best,
> catia
>
>
>
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Catia Nicodemo



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