> From: Peter Flom [mailto:flom@ndri.org]
>
> Hello
>
> I am running S-Plus 6 on a Windows machine.
>
> I am trying to fit a classification tree with independent variables
> that are ordinal. However the result does not take the ordinalaity of
> the variables into account. e.g., one variable has levels A
> through H.
> I have made this an ordinal factor in the data window. But the tree
> gives splits such as
>
> AC BDEFGH
>
> I had thought of perhaps numericizing the scale, but this doesn't seem
> ideal to me. Is there a better solution?
I believe this is close to ideal. That's what I did in the randomForest
package. There is no difference between ordinal and numerical variables
with respect to the way the algorithm searches for best splits.
HTH,
Andy
> Thanks in advance
>
> Peter
>
>
>
> Peter L. Flom, PhD
> Assistant Director, Statistics and Data Analysis Core
> Center for Drug Use and HIV Research
> National Development and Research Institutes
> 71 W. 23rd St
> New York, NY 10010
> (212) 845-4485 (voice)
> (917) 438-0894 (fax)
>
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