Re: st: clogit data format

[Margaret R Grove <margaret.r.grove@Dartmouth.EDU>]

To clarify further where I think the problem may lie:

PHREG output notes "Number of Observations Read   2300" and "Number of 
Observations Used  2000" (300 have missing values for the dependent 
variable)

CLOGIT notes that 1710 observations (496 groups) were dropped because of 
all negative or all positive outcomes and our final number of 
observations is 290!

With this I wonder if comparing the two methods makes sense and which 
method (PHREG or CLOGIT) is preferable (if any)?

Thank you!
Margaret




Nick Cox wrote:

> Be that as it may, the report of "very different answers" is pretty
> difficult
> to discuss without any details whatsoever.
>
> Nick
> n.j.cox@durham.ac.uk 
> Margaret R Grove
>
> I've seen examples of SAS PHREG and Stata clogit used on the same data 
> at the following web site:
>
> http://www.indiana.edu/~statmath/stat/all/cdvm/cdvm7.html
>
> Svend Juul wrote:
>
>   
> > Margaret wrote:
> >  
> > I'm attempting to use clogit and have a very basic 
> > question about the data format. It seems like it 
> > should be obvious but I'm getting very different 
> > answers than a colleague using SAS PHREG.
> > ...
> >  
> > ====================================================
> >  
> > Isn't SAS PHREG about proportional hazards regression
> > (Cox regression)? Stata's -clogit- performs conditional
> > logistic regression; in my understanding this is quite
> > a different analysis.
> >     
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>   
--
__________________________
Margaret R. Grove, MS
Research Associate/Analyst, TDI
1 Medical Center Drive, Room 570
Lebanon, NH 03756
Tel: 603-653-3560
Fax: 603-653-3558

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