[R] Logistic Regression

[Bert Gunter]

IMHO, you evidence considerable confusion and misunderstanding of
statistical methods. I would say that most of what you describe is
nonsense. Of course, maybe I'm just the one who's confused, but I
would strongly suggest you consult with a local statistician. This
list is unlikely to be able to provide you the level of support and
understanding that you need.

Cheers,
Bert

On Tue, Jun 7, 2011 at 1:38 AM, farahnazlakhani
<farah.farid.n09 at student.aku.edu> wrote:
> I am working on my thesis in which i have couple of independent variables
> that are categorical in nature and the depndent variable is dichotomus.
> Initially I run univariate analysis and added the variables with significant
> p-values (p<0.25) in my full model.
> I have three confusions. Firstly, I am looking for confounding variables by
> using formula "(crude beta-cofficient - adjusted beta-cofficient)/ crude
> beta-cofficient x 100" as per rule if the percentage of any variable is >10%
> than I have considered that as confounder. I wanted to know that from
> initial model i have deducted one variable with insignificant p-value to
> form adjusted model. Now how will i know if the variable that i deducted
> from initial model was confounder or not?
> Secondly, I wanted to know if the percentage comes in negative like
> (-17.84%) than will it be considered as confounder or not? I also wanted to
> know that confounders should be removed from model? or should be kept in
> model?
> Lastly, I wanted to know that I am running likelihood ratio test to identify
> if the value is falling in critical region or not. So if the value doesnot
> fall in critical region than what does it show? what should I do in this
> case? In my final reduced model all p-values are significant but still the
> value identified via likelihood ratio test is not falling in critical
> region. So what does that show?
>
>
> --
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-- 
"Men by nature long to get on to the ultimate truths, and will often
be impatient with elementary studies or fight shy of them. If it were
possible to reach the ultimate truths without the elementary studies
usually prefixed to them, these would not be preparatory studies but
superfluous diversions."

-- Maimonides (1135-1204)

Bert Gunter
Genentech Nonclinical Biostatistics