Re: [R] Repost: Examples of "classwt", "strata", and "sampsize" in randomForest?

From: David L. Van Brunt, Ph.D. <dlvanbrunt_at_gmail.com>
Date: Fri 28 Oct 2005 - 01:54:32 EST

I have read both the help files and that article... the article very nicely evaluates the value of dealing with unbalanced data, and the help files show that you can, but offer no guidance in terms of how the syntax should be specified. The "strata" and "classwt" clearly can be specified, but it's not shown how to specify the values...

The examples do not include specifications of those terms, and every guess I've made has generated an error....

On 10/27/05, Gabor Grothendieck <ggrothendieck@gmail.com> wrote:
>
> See
> http://finzi.psych.upenn.edu/R/Rhelp02a/archive/40898.html
>
> On 10/27/05, David L. Van Brunt, Ph.D. <dlvanbrunt@gmail.com> wrote:
> > Sorry for the repost, but I've really been looking, and can't find any
> > syntax direction on this issue...
> >
> > Just browsing the documentation, and searching the list came up short...
> I
> > have some unbalanced data and was wondering if, in a "0" v "1"
> > classification forest, some combo of these options might yield better
> > predictions when the proportion of one class is low (less than 10% in a
> > sample of 2,000 observations).
> >
> > Not sure how to specify these terms... from the docs, we have:
> >
> > classwt: Priors of the classes. Need not add up to one. Ignored for
> > regression.
> >
> > So is this something like "... classwt=c(.90,.10)" ? I didn't see the
> syntax
> > demonstrated. Similar for "strata" and "sampsize" though there is a
> default
> > for sampsize that makes sense... not sure how you would make "a vector
> of
> > the length the number of strata", however....
> >
> > Pointers?
> >
> > --
> > ---------------------------------------
> > David L. Van Brunt, Ph.D.
> > mailto:dlvanbrunt@gmail.com
> >
> > --
> > ---------------------------------------
> > David L. Van Brunt, Ph.D.
> > mailto:dlvanbrunt@gmail.com
> >
> > [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help@stat.math.ethz.ch mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide!
> http://www.R-project.org/posting-guide.html
> >
>

--
---------------------------------------
David L. Van Brunt, Ph.D.
mailto:dlvanbrunt@gmail.com

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Received on Fri Oct 28 04:38:19 2005

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