Date: Fri, 1 Dec 2006 10:45:16 -0500
Reply-To: Wensui Liu <liuwensui@GMAIL.COM>
Sender: "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From: Wensui Liu <liuwensui@GMAIL.COM>
Subject: Re: Decision Tree refuses to grow
In-Reply-To: <1164819018.146780.300870@h54g2000cwb.googlegroups.com>
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what tree algorithm are you using?
I don't know how tree algorithm works in sas/ Eminer. but split method
of some tree algorith doesn't depends on p-value at all, such as CART.
My suggestion is to check the default setting of your program. A study
indicates that analysis result is highly sensitive to the default
setting of software, which is pretty interesting.
On 11/29/06, amw5gster@gmail.com <amw5gster@gmail.com> wrote:
> Howdy,
>
> Silly question that's likely to show I'm overlooking something simple,
> but I'm stumped. I have a dset of approx 8M observations and I'm
> trying to grow an EMiner decision tree on a binary target variable.
> There are about 20 independent variables, mostly interval (dates), but
> some nominal, a few binary and one ordinal. The proportion of true
> events is about 12%. I have not set any prior probabilities, nor
> profit/cost values.
>
> The tree runs, but returns no splits. It just won't grow. I've tried
> dropping the signif value to .00001, using upwards of 11 maximum
> branches and my max depth to 10. I also tried having the tree build on
> as few as 2 IVs.
>
> I was able to build a tree when I took a sample of 100K records and
> forced the %age of true events in the sample to be 50%. Naturally I
> don't want to misrepresent the proportion, and I figured that 12%
> wasn't terribly rare for a d-tree.
>
> Am I outright doing something wrong or is this expected behavior?
>
--
WenSui Liu
(http://spaces.msn.com/statcompute/blog)
Senior Decision Support Analyst
Cincinnati Children Hospital Medical Center
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