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Re: st: clogit data format

From   Margaret R Grove <margaret.r.grove@Dartmouth.EDU>
Subject   Re: st: clogit data format
Date   Thu, 20 Mar 2008 11:54:57 -0400

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!

Nick Cox wrote:

Be that as it may, the report of "very different answers" is pretty
to discuss without any details whatsoever.

Margaret R Grove

I've seen examples of SAS PHREG and Stata clogit used on the same data at the following web site:

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.
* For searches and help try:
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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