Dear Peter,
There's no reason not to use numbers to represent the factor -- any numbers
in the correct order will do, such as integers 1 through 8. Splits will be
between adjacent numbers and hence will preserve the order of the factor.
I hope that this helps,
John
At 10:57 AM 1/30/2003 -0500, you wrote:
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?
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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John Fox
Department of Sociology
McMaster University
Hamilton, Ontario, Canada L8S 4M4
email: jfox@mcmaster.ca
phone: 905-525-9140x23604
web: www.socsci.mcmaster.ca/jfox
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