[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Subscribe]
AW: DM: RE: Data Forms for Mining (Limit on variables)From: Frank Buckler Date: Wed, 24 May 2000 11:15:15 +0200 Issue: Number of Inputs I'm surprised to hear that some guy's are using from thousand up to million of inputs. There exist an upper bound on input-number determined by sample size. This is advocated due to the VC-Dimension. For linear regression you need n+1 examples in sample (n = number of input) This is true but much more severe for non-linear modelling! frank -----Ursprüngliche Nachricht----- Von: owner-datamine-l@nautilus-sys.com [mailto:owner-datamine-l@nautilus-sys.com]Im Auftrag von greg.della-croce@marchFIRST.com Gesendet: Dienstag, 23. Mai 2000 15:01 An: datamine-l@nautilus-sys.com Betreff: Re: DM: RE: Data Forms for Mining Eric, I think you miss read the line. It is 700 Variables, not characters. But that does bring up an interesting question. IF DM uses a 0NF to lay out data (all the info for any given instance in one record) What are the practical limits of the tool, today, for the number of variables in that record. I am currently working with biomed field and that could very easily go into the hundreds of varables per instance. Anyone have any input on this? Greg Eric Bloedorn <bloedorn@mitre.org> on 05/22/2000 12:17:37 PM Please respond to datamine-l@nautilus-sys.com To: datamine-l@nautilus-sys.com cc: (bcc: Greg Della-Croce/Whittman-Hart LP) Subject: Re: DM: RE: Data Forms for Mining Ken: I am curious - what commercial tools choke and die on tables wider than 700 chars?! -Eric Bloedorn, MITRE Corporation "Collier, Ken" wrote: > > This question hit a hot-button for me. While most OLAP and DSS technology > require a great deal of structure in thier data (e.g., start schema), data > mining tools expect the data to be denormalized into a single 2D table. > Furthermore, aside from market basket analysis, most data mining algorithms > assume that each observation in a data set represents a unique entity (e.g., > each record is a different customer). > > What this implies is that there is substantial data preprocessing required > in most cases to transform data from a relational, star, or other structured > model, into the mineable denormalized structure required. In our experience > with retailers, telecos, manufacturers, insurance companies, banks, and > others, this preprocessing generally consumes about 80% of the total effort > compared to the actual data mining, validation, verification, and > deployment, which consumes the remaining 20%. Your mileage may vary. > > Now, here's the rub: We recently had a manufacturing client with ~1000 > quality control parameters for each component within a single widget. In > this scenario a widget is made up of 2-6 major sub-widgets, and each > sub-widget is made up of 3 components. The same set of QC parameters is > collected on each component. So, even when we denormalize the data into a > single table, there can be as many as 18 (6 x 3) records for a single > widget. Our objective in this analysis was to identify root causes of widget > failure in order to reduce the defect rate. > > Now, we want the data mining algorithms to "see" all 18 records associated > w/ a single widget as a single "pattern". Unfortunately commercial tools > don't tune their algorithms to do this even though it is technically > possible. One exception is time series and sequence analysis algorithms, but > these methods are really intended for a different purpose. Another kludgy > solution to this problem is to string out all 18 records into a single WIDE > record per widget. Many commercial tools choke and die on tables that are > wider than 700 vars. > > We finally wound up solving this problem using SAS Enterprise Miner and SGI > Mineset, but not without a lot of data transformations, preprocessing, and > preliminary variable reduction. To my thinking, the next generation of data > mining tools should provide the flexibility to "see" data in a wide variety > of structures. The price we may pay for this flexibility is the speed of > data sourcing prior to analysis. > --- > Ken Collier > Senior Manager, Business Intelligence > KPMG Consulting > Corporate Sponsor of the Center for Data Insight http://insight.cse.nau.edu > > -----Original Message----- > From: greg.della-croce@marchfirst.com > [mailto:greg.della-croce@marchfirst.com] > Sent: Thursday, May 18, 2000 6:09 AM > To: datamine-l@nautilus-sys.com > Subject: DM: Data Forms for Mining > > I have worked in and around Data Warehouse/Marts with their star schema for > awhile now. However I am interested what form the data takes when it is > being > optimized for Mining. I am speaking to structured data, not unstructured > data > such as large bodies of text. What are the architectures of a Data Mining > DB? > Is the form dependent on the algorithms that you are going to employ > against it? > Or is it more general in nature? > > Thank you for your replies! > > Greg Della-Croce > marchFirst > BI/KM > > **************************************************************************** * > The information in this email is confidential and may be legally privileged. > It is intended solely for the addressee. Access to this email by anyone else > is unauthorized. > > If you are not the intended recipient, any disclosure, copying, distribution > or any action taken or omitted to be taken in reliance on it, is prohibited > and may be unlawful. When addressed to our clients any opinions or advice > contained in this email are subject to the terms and conditions expressed in > the governing KPMG client engagement letter. > **************************************************************************** *
|
MHonArc
2.2.0