Tal Galili wrote:
> Hello Frank,
>
> Thank you for the extension and remarks.
> The basic weakness of stepwise regression VS going through all-subsets
> is very much agreed upon. Although from what I gather there is one case
> where all subsets will be a problem to implement, that is for very LARGE
> datasets - especially in the sense of a lot of explanatory variables,
> and also with regards to cases where we have more explanatory variables
> then data points.
> In such cases I wonder if using stepwise regression could be found to be
> more realistic to implement then all subsets checks.
> Then again, I imagine (although not from real experience) that shrinkage
> methods (used with LARS) could be practical in those cases too.
>
>
>
> I am looking forward to meeting you on Tuesday and taking your first
> tutorial of the day,
I look forward to seeing you in Rennes.
>
> With regard,
> Tal
All subsets regression is an especially bad form of stepwise regression.
It has terrible operating characteristics.
Cheers,
Frank
>
>
>
>
>
>
>
> On Sat, Jul 4, 2009 at 4:22 PM, Frank E Harrell Jr
> <
f.harrell@... <mailto:
f.harrell@...>> wrote:
>
> sed for one variable at a time variable selection. AIC is just a
> restatement of the P-value, and as such, doesn't solve the severe
> problems with stepwise v
>
>
>
>
> --
> ----------------------------------------------
>
>
> My contact information:
> Tal Galili
> Phone number: 972-50-3373767
> FaceBook: Tal Galili
> My Blogs:
>
http://www.r-statistics.com/>
http://www.talgalili.com>
http://www.biostatistics.co.il>
>
--
Frank E Harrell Jr Professor and Chair School of Medicine
Department of Biostatistics Vanderbilt University
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