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Article #33Re: How to improve decision tree classification model error rate?
From: Arthur J. Kendall
Date: Wed, 12 Jun 2002 13:13
Date: Wed, 12 Jun 2002 13:13
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3417 bytes
It seems that you want to reduce each time series to a a few parameters and cluster those parameters. The Classification Society of North America page http://www.pitt.edu/~csna/ might be of help. I have seen this kind of problem at past CSNA meetings. Browse the abstracts etc. You might post a message on <class-l> describing your data and the kind of questions you have. Eric Bohlman wrote: > In sci.stat.math Alexander Sirotkin <demiurg@tau.ac.il> wrote: > > There is an information in this data set that may current > > classification model does not use. The model does not take into > > account taht these 562 real predictor variables (not records !!!) > > have order, meaning that the variables are not just x[1], x[2],..., x[561] > > but it is important that x[3] comes after x[2] (because these variables > > are actually samples from continues function). > > > what I'm trying to do, actually, is to build a classification model > > using functions (sampled at 562 points) as independent variables ! > > Ah, you're saying that your independent variables are actually the values > of a time series. In that case, some of your difficulty may be coming > from the fact that they're so highly correlated that it's difficult to > distinguish the weights that should be assigned them. > > It looks like you're really trying to estimate the coefficients of a > finite-impulse-response filter whose output is then somehow quantized into > 80-something not-necessarily-equal-sized steps. I'm not really sure how > to deal with such a problem. One thing that's clear is that anything > resembling classical discriminant analysis isn't going to work with your > sample size of around 10,000, because it would require estimating around > 45,000 parameters which is almost 5 times the number of independent > observations you have. I also have a very strong hunch that your apparent > "success" with stepwise methods is actually success at fitting the noise, > rather than signal, in your data.
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X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 10d632,777798b8d4d7b811 X-Google-Attributes: gid10d632,public X-Google-Thread: fa931,777798b8d4d7b811 X-Google-Attributes: gidfa931,public X-Google-ArrivalTime: 2002-06-12 06:13:00 PST Path: arc1-ca.pugleaf.net!archiver1.google.com!news1.google.com!newsfeed.stanford.edu!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!news-out.nuthinbutnews.com!propagator-sterling!news-in.nuthinbutnews.com!cyclone1.gnilink.net!spamfinder.gnilink.net!nwrddc02.gnilink.net.POSTED!53ab2750!not-for-mail Message-ID: <3D0748DB.E857635D@verizon.net> From: "Arthur J. Kendall" <Arthur.Kendall@verizon.net> Reply-To: Art@DrKendall.org X-Mailer: Mozilla 4.79 [en] (Windows NT 5.0; U) X-Accept-Language: en MIME-Version: 1.0 Newsgroups: sci.stat.math,aus.stats.s Subject: Re: How to improve decision tree classification model error rate? References: <adrouf$h81$1@mulga.cs.mu.OZ.AU> <mka9gukh228jdm993ht1erdo793j6f52ig@4ax.com> <dd39f296.0206111402.1284fba8@posting.google.com> <ae7gpn$2et$1@bob.news.rcn.net> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Lines: 41 Date: Wed, 12 Jun 2002 13:13:01 GMT NNTP-Posting-Host: 141.156.182.59 X-Complaints-To: abuse@verizon.net X-Trace: nwrddc02.gnilink.net 1023887581 141.156.182.59 (Wed, 12 Jun 2002 09:13:01 EDT) NNTP-Posting-Date: Wed, 12 Jun 2002 09:13:01 EDT