Well, if it is constant across the entire estimation sample, it cannot
possibly contribute to the explanation of the variance in the dependent var.
But that is not specific to logistic regression.
*********
sysuse auto, clear
g q=1
reg pr we tu q
logit foreign displacement turn q
*********
If the var is inherently unable to contribute anything useful, this issue
does not "affect the analysis" in that you do not lose anything useful.
HTH
Martin
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Sampaio, Marcelo
Sent: Tuesday, August 26, 2008 4:03 AM
To: [email protected]
Subject:
Dear all
I am a reserch fellow and I use stata to my analysis. I would like to know
what we should do when in a multiple logistic analysis we have a output
saying that the variable was dropped by estimability or dropped because it
is constant. How can we fix it and how much it affects the analysis?
Thanks
Marcelo Sampaio
Resech Fellow
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