R help - Oct 2009 - output (p-values) of "fastbw" in Design package

I am using the validate option in the Design package with the Cox survival
model.
I am using the bw=T option which, like the fastbw function, performs a backward
elimination variable selection
The output includes a series of columns (below) giving information on eliminated
variables.
My question is that I am unsure of the difference between the 2 p-values given
(the one after Chi-Sq and the one after df)
This may be a gap in my statistics knowledge, hopefully I've not asked too
silly a question, many thanks in advance

                Backwards Step-down - Original Model

 Deleted    Chi-Sq d.f. P      Residual d.f. P      AIC

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North, Bernard V wrote:
> I am using the validate option in the Design package with the Cox survival
model.
> I am using the bw=T option which, like the fastbw function, performs a
backward elimination variable selection
> The output includes a series of columns (below) giving information on
eliminated variables.
> My question is that I am unsure of the difference between the 2 p-values
given (the one after Chi-Sq and the one after df)
> This may be a gap in my statistics knowledge, hopefully I've not asked
too silly a question, many thanks in advance
> 
>                 Backwards Step-down - Original Model
> 
>  Deleted    Chi-Sq d.f. P      Residual d.f. P      AIC
The first chi-sq stat is the individual partial chi-sq for testing the 
deleted variable, adjusted for all variables still in the model.  The 
residual chi-sq test is the simultaneous test for all variables deleted 
up to and including the current one.

Frank



-- 
Frank E Harrell Jr   Professor and Chair           School of Medicine
                      Department of Biostatistics   Vanderbilt University