Date: Wed, 7 May 1997 10:07:43 -0400
Reply-To: Ismail Parsa <iparsa@EPSILON.COM>
Sender: "SAS(r) Discussion" <SAS-L@UGA.CC.UGA.EDU>
From: Ismail Parsa <iparsa@EPSILON.COM>
Subject: Re: chaid on sas
|> From: Edward Malthouse <ecm@NWU.EDU>
|> Subject: Re: chaid on sas
|> I have used SPSS' version of CHAID and found it to be very dangerous. The
|> problem I have with it is that it is prone to overfitting the data -- I get a
|> nice tree and decent fit statistics, but when I apply it to another data set
|> the predictions are not so good.
Tighten your stopping criteria and don't opt for a large/long tree.
|> I have had much better luck with Splus' CART (classification and regression
|> trees is an improved version of chaid) functionality. It includes options
The two are not technically related. CART uses purity measures, like GINI index
or entropy whereas CHAID uses chi-sqaure criterion in building trees.
|> that automate the process of validating the model with holdout samples.
You can certainly score a validation sample using CHAID.
| Ismail Parsa |
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|> I sincerely hope that SAS does not follow SPSS' model for CHAID.
|> Ed Malthouse
|> In article <19970430.161151.580850.NETNEWS@AUVM.AMERICAN.EDU>,
|> "Zhang, Alex - O&MD NY" <OGILVY!OMDNY1!ZHANGAL@OMDNY.ATTMAIL.COM> wrote:
|> >I was told at a SAS seminar about a month ago that CHAID and neural network
|> >are only available through SI's Professional Service as part of the
|> >customized packages. SI is planning to release a data mining product which
|> >will include CHAID at the end of this year. A beta version may be available
|> >as early as this Summer.
|> >Alex Zhang
|> >Ogilvy & Mather Direct
|> > ----------
|> >From: Philip Holland
|> >To: Multiple recipients of list SAS-L; ZHANGAL
|> >Subject: Re: chaid on sas
|> >Date: Wednesday, April 30, 1997 4:54PM
|> >skmxx <firstname.lastname@example.org> wrote:
|> >>Hi! everyone.
|> >>I need your advice. I want to run CHAID on sas, but, I cannot find
|> >>where. In sas/stat manual I could not find any word CHAID on the index.
|> >>I know there is CHAID option on spss. On sas where is this option or
|> >>comparable option? I really appreciate your advice.
|> >>Soo Hong Kim
|> >>Graduate Student
|> >>Syracuse Univ.
|> >I believe there are some SAS macros for CHAID stats
|> >processing, supplied by the SAS Institute. I suggest you
|> >contact your local SAS office, but be warned that they may not
|> >be free...
|> >HTH..............Philip R Holland <email@example.com>
|> > Holland Numerics Ltd
|> > Royston, Herts, UK
|> > mobile: +44-(0)850-295556
|> Edward Malthouse
|> Assistant Professor
|> IMC Department
|> Medill School of Journalism
|> Northwestern University
|> Evanston, Illinois