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logistic regression

To: s-news <s-news@lists.biostat.wustl.edu>
Subject: logistic regression
From: AHC van Kampen <a.h.vankampen@amc.uva.nl>
Date: Thu, 31 Jul 2003 17:45:01 +0200
Reply-to: a.h.vankampen@amc.uva.nl
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Hi,

I'm new to logistic regression and therefore this stupid question:

What I have understand from logistic regression is that the binary response variable is transformed to log(p/(1-p)). 1) How is the fraction p calculated for an individual response value (0 or 1). Probably, if for a certain predictor value only 1 response is available the fraction is aslo always 1 or 0, or is the fraction p calculated a pre-specified range for a predictor value?

2) I'm analysing the Kyphosis dataset that comes with Splus. How are these binary response values transformed and how can i check in Splus how this was done. Is there any variable that contains the transformed response values?

Any help is appreciated

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  | Dr. Antoine H.C. van Kampen         |
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