On Thu, 13 Dec 2001, Jeff Hammel wrote:
> I'm doing some tree-based modeling in both S-plus
> version 6.0 for UNIX and S-plus 2000 in Windows
> 2000. My understanding is that the node splitting
> is based on a reduction in deviance, which in the
> case of regression trees is equivalent to using
> the reduction in sum of squared deviations from
> the means.
true, although there is also an approach via impurity
indices, which is really what rpart implements (and
the defaulut Gini index for classification trees is one
example).
> Are there other choices available for
> the splitting criterion for regression trees
> either in the built-in S-plus tree functions or
> those in the rpart library? If not, has anyone
Not visible, at least. (Surely it would be on the help page if there
were?)
> implemented his/her own splitting criteria?
The latest rpart allows users to plug their own criteria in. I had
understood Terry Therneau had sent the code to statlib fairly recently,
but I couldn't see it there.
--
Brian D. Ripley, ripley@stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272860 (secr)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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